Black Box Vac Source

[Gary Campbell]

Here is a project I have been working on for a while in my spare time. Now that it is up and running, I thought I would post a few pics and the specs.

There have been dozens, if not more, versions of enclosures for aftermarket vacuum motors posted and this is not that different in construction, but control. Either 2 or 4 of these motors can be operating at a time and switchover is done using relays and a vac switch from Joe Woodworkers kit parts.

The vac source consists of 4 Lighthouse Brand LH-7123 240V motors. These are 10.4 inHg/110 cfm units each. Combined they should pull close to 10 inHg and have close to 400 cfm. Testing has shown this to be a very powerful vac source, and holds over 9 inHg when applied to less than the full 4 zones.

Box is made from Melamine, full dado joints using eCabs for design. Assembled using silicone for seal/adhesive and screws with finish washers.

I used a 24V 3PDT 10A relay for each motor. A vac switch, set to approx 7 inHg, kicks in 3rd and 4th motors, should the vac fall below 7.5 inHg when cutting. There is a check valve, a' la Brady Watson between the 2 pairs of motors. Control is low voltage remote at front of table and allows full automatic, 2 only or all 4 as options.

Here are the pics of construction. I will post installed later.

[Gary Campbell]

The box has a number of dividers that keep the intake cooling, exhaust cooling and vacuum exhaust separated. Both exhausts are diverted thru baffles and diected to the floor. The cooling intake is on one end and filtered. This combination has proven to be much quieter than my previous setup, but not as quiet as I wished for. Perfomance is great. Its cool to watch the vac gauge go down below 8 and hear the 2nd pair kick in. Gauge climbs to over 9.

More pics

[sailfl]

Gary,

Are you going to try to make it quieter? How bad is the noise?

Great job.

[gene]

Could you use a sound deadening foam to help the noise levels? I recently built some displays for a music store and they had a foam contoured padding on the walls to cut down on noise transfer from room to room.

[Gary Campbell]

Guys....
No efforts to reduce noise will be taken on this end. Anything that would quiet it down would either add heat or reduce power. I can carry on a conversation with my son when it running. MUCH quiter than my previous system with 4 unenclosed motors. MUCH quieter than many of our other machines.

I dont think anything that moves that much air can be quiet. The biggest gain may have been in the high pitched intake of the cooling fans, as that noise is near gone.

[Brady Watson]

Bravo! Looks like you really put some thought into the design & functionality.

-B

[Gary Campbell]

Brady...
Thanks for the kudo.

What I remembered, and sometimes forget to tell others, is to reread what you have posted. You, my friend are THE source for vac hold down information.

The check valve and article you sent to our user group some time back was the central idea behind this. Without a simple and foolproof vac valve, it couldnt work. Until I read your write up, I never realized it could be so simple.

Thanks again.

[Gary Campbell]

In response to the emails for info, I think this may clear it up:

[sailfl]

Gary,

Could you supply this, "The check valve and article you sent to our user group". Thanks

[wberminio]

Gary
This is the best use for melamine I've seen in years!

[Brady Watson]

Re-print of what I sent to Gary last year:
__________________________________________________ __________

BradyVac “Ova Da Hump” Valve
A sucky short story about the marriage between a Fein & a Gast…

This is just a quick write up for you guys @ Gary’s camp. Sorry I can’t make it, but family duty calls…and work is really busy…

Here’s a little contraption that I came up with a while back to aid in holding down non-porous material while using a low CFM, high Hg” vacuum pump, like a small Gast or Welch ½ HP or even a venturi type system that works in conjunction with your air compressor. This setup is designed to be used in what I call a ‘closed system’, meaning that it is NOT intended to be used with a bleeder board or BradyVac v1. You can use a BV2 if you use non-porous materials. (For more info on BradyVac configs, visit my write up on the SB website and/or forum) Plastic jigs and setups work best.


In my experience, sometimes part hold-down is difficult if your material is not absolutely dead flat. For example, the stippled-back of fiberglass or carbon fiber woven layups prevent a high suction/low CFM vacuum from ever getting over the hump and sealed to the gasketing. This prevents your low CFM/High Hg” (LFHS – Low Flow High Suction) setup from being able to make a seal against the gasketing, and your high CFM, Low Hg” Fein or other vacuum source (HFLS) doesn’t generate enough negative pressure to hold the part down while machining. Many times, holding your hand on the part to get it to seal is a pain, and depending on material, it may not seal at all with this method.

Using a HFLS vacuum source, like a Fein Turbo III, the material pulls down and ‘gets over the hump’- but with low negative pressure, it is not enough to hold your small parts. The HFLS vacuum is EXCELLENT at sealing off the material to the jig & the LFHS (Gast) is great at keeping that part held down, provided that leakage is kept to a bare minimum.

Using the good ole principles of pressure differentials, I sought out a way to have the vacuum automatically switch from HFLS to LFHS. This would let me seal off my part to the jig and then build the necessary vacuum pressure to keep my finished parts held down against the forces of the cutter. I discovered that a regular old sewage check valve was just the ticket. It was cheap (I think around $7) and it allowed me to directly connect the Fein to it. (Even came with hose clamps!) A short length of 2” PVC pipe was drilled and tapped to accept a small quick release hose fitting. The open side of the PVC is connected to my vac jig and the LFHS vacuum is piped to the quick release nipple. The valve is situated so that the Fein (or other HFLS) opens the flapper valve when it is turned on.

In operation, the Fein pulls the flapper valve open and begins building vacuum. Once the Fein tops out (around 7” Hg), the small LFHS pump quickly builds vacuum until it tops out, providing that there are no leaks. As the LFHS pulls past 7” Hg, the pressure differential in the sewer valve causes the flapper to suck closed. This seals off the Fein from the rest of the system and at that point it can be turned off. The Fein can be left on as a sort of insurance policy, if your part is barely held down with 7” Hg. If the vacuum pressure drops to under 7” Hg, the valve is then sucked open by the Fein and pressure is then maintained up to 7” Hg, by the Fein unless leakage is really excessive.

I know that this isn’t the only use for this type of setup. I bet that it can be used in other ways in conjunction with anything that moves a lot of air and something else of higher suction. I have confirmed that it works really well with vacuum bagging, especially where open glue times are short, and even thermoforming where you need to generate vacuum quickly to keep production up.

Note that since I made this, I discovered that the setup really benefits from using larger tubing on the Gast inlet nipple. Go as large as you can since the pump can choke and lose a lot of it’s air flow (CFM) if the tubing is too small. It will generate vacuum just fine, but the larger tubing helps to get the most out of the pump.

Hope all of that makes sense…

-B

__________________________________________________ ____

PICS -

__________________________________________________ ____

http://www.talkshopbot.com/forum/picture.php?albumid=21&pictureid=124

http://www.talkshopbot.com/forum/picture.php?albumid=21&pictureid=123

http://www.talkshopbot.com/forum/picture.php?albumid=21&pictureid=122

[Brady Watson]

More pics...

http://www.talkshopbot.com/forum/picture.php?albumid=21&pictureid=121

http://www.talkshopbot.com/forum/picture.php?albumid=21&pictureid=120

http://www.talkshopbot.com/forum/picture.php?albumid=21&pictureid=118

See what else you guys can come up with using this setup...

-B

[frank134]

gary great design you are the man. some of the stuff you made and come up with is really great. can I ask what made you pick that vac motor to used out of all the one's that he sells. I am also a little confuse on the check valve and what it is used for. One of these day if you every give me a change I may catch up to you.

[Gary Campbell]

Brady...
Thanks for the post, I dont have my copy on this computer. Your pics are not posting?

Erminio...
Yes... I have cut 1 1/2 sheets of it now! Not looking forward to the next one. Do you know what that stuff weighs? :D

Frank...
My very first motors were the Euro (220V) Fien replacement from Granger. My second set were the Ametek 117123 (240V) selected because they had more vac & cfm. These are the LH branded replacement for the 2nd set of Ameteks. Also known as the 240V version of the 9-15 open source vacuum that Brady "donated" to the group.

Using the theory and knowledge that Brady talks about in his "Ova da Hump" valve system, which is an ingenious use of a common plumbing check valve to marry a high vac low volume source to a high volume low vac source, I used the same theory to separate 1 pair of motors from the other, but yet allow them to be used together.

When "front" pair (of my vac box) that is connected to the manifold cant maintain over 7 inHg, a vacuum switch (like on a compressor only neg pressure) kicks in the "rear" pair. Since the rear pair will develop 10 inHg in a couple seconds, it sucks the check valve open and allows the 2 rear motors to double the cfm and increase the vacuum in the system. since the front pair is connected to the plenem, there will always be less pressure (actually more, but less vac potential) on that side of the check valve. If the front pair can maintain over 7 inHg, then the check valve keeps the rear chamber sealed from the system. Without it, the rear pair would allow vacuum to leak into the front chamber. There is also angled tabs on the check valve to keep it from being sucked up into the intake of the motor closest to it. Simple...but effective.

Ran it for about 5 hrs continuous today, box gets about 110 degees +/-. And those that called know I can talk on the phone next to the bot while its running.

[frank134]

OK thank Gary that was simple. I must be breathing to much saw dust these days. I should of thought of that. I have the older set like you used to have. I change it a little. But the noise is way too much. I can't think. I like your new setup and the back of my bot is only 5 foot from the back wall. I was thinking of a little room outside and placing it in there. Running it with relay would be easy and better then valve. I also wanted to thank you for the idea of the indexing using the cylinder. Boy does that work great. That was also one of your great ideas. I really like it. Best part after I square and clamps things I can remove it. Keep on thinking I am loving it.

[hespj]

Thanks Gary & Brady. Interesting point about vacuum bagging Brady.

John

[ken_rychlik]

Very nice design Gary.

One question, Does the second set latch on when the vac falls below the set vac switch to keep it from "fluttering" the second pair of motors off and on?

[Brady Watson]

No problem guys...I've got a whole lot of little things like this from my R&D sessions. It's just a matter of time documenting or posting them for others to use.

I can see the pics just fine...Can everyone see the pics?

-B

[ken_rychlik]

No pictures that I can see

[road_king]

Can't see any pics here. Thanks for posting additional information.

Gerald

[Brady Watson]

Very strange...I can see the pics just fine from either computer I tried...I uploaded them to the forum 'bucket'...

Let's try this again:

http://i772.photobucket.com/albums/yy8/braidmeister/1.jpg

Valve Open
http://i772.photobucket.com/albums/yy8/braidmeister/2.jpg

Valve Closed
http://i772.photobucket.com/albums/yy8/braidmeister/3.jpg

[Brady Watson]

http://i772.photobucket.com/albums/yy8/braidmeister/4.jpg

http://i772.photobucket.com/albums/yy8/braidmeister/5.jpg

http://i772.photobucket.com/albums/yy8/braidmeister/6.jpg

[Brady Watson]

Sorry...but you'll have to refer back to Page 2 (http://www.talkshopbot.com/forum/showthread.php?t=11813&page=2) and read the write-up I sent Gary for the pics to make sense. It's too long to re-post here...

-B

[road_king]

I can see the pics now posted. Thanks.... I've been thinking about setting up a vacuum and I think this is what I will end up with. Thanks again!!

Gerald

[Gary Campbell]

Brady...
Even my old eyes can see 'em now!

Kenneth....
The first switch I tried did just that... short cycled. As soon as they came on... they went off. I tested a coule different ones that I had and found one with about 3 inHg differential. That did the trick. My first only had about 1.5" swing.

Differential is the difference between the on and off switch points. An example would be an air compressor. Comes on at 100 psi, goes off at 135 psi. Differential is 35#. Only a high end vac switch has a differential setting. On Joe WW site its advertised as 1-5 inHg.

[cip]

Gary; After reading your post about the noise still not being as quiet as you would like I had a conversation with one of my clients, an acoustics company, about the problem. One of the things that they said was never use round holes unless it's really necessary. Something about the round causes a turbulence and hence noise. Use oval of even better square with a baffle if possible. I looked at the mufflers that I bought for the vac motors and sure enough they were square. They also said the air noise is one the hardest to eliminate unless one can completely seal the unit and we know that this isn't possible due to the heat factor. Maybe this will help for future development.

Mike

[Gary Campbell]

Mike...
Long time no see! How are things in WPB?

Please understand, no piece of equipment that I own is as quiet as I would like. "The Box" is only about as loud as a shopvac. Quieter than my small dust collector or air compressor, MUCH quieter than the big DC, planer etc.

I prefer to enjoy the power and not expend energy trying to quiet things down in a room where I wear hearing protection.

[Gary Campbell]

My vac gauge came in. Now the LV control panel is complete. (for now)

We are going to add solenoid control of the zone valves and zone indicators in the future.

Here is a pic

[ward]

WOW, I have not looked for a long time to see what you are doing with our Lighthouse Brand motors. What a beautiful addition to your Shop Bot table.

Your creativity never seems to end - Great Job!

[Gary Campbell]

Ward...
Thanks for the more than kind words. This project becomes easy when using motors with as much "snot" as these have. Thanks for the advice.

I have just upgraded to SMC digital switches for the motor switching. having a very predictable set point is much better. The good news is that I am getting 8.6 inHg with a covered spoilboard. This is only a little less than I was getting during the closed pipe testing. (a little over 9 on an analog gauge) This is as expected for our altitude and inherent leakage when using a spoilboard.

Thanks again

[Gary Campbell]

Update...
We have used this for over a month now. In a few cases, it has been run continuous for 6 hrs with no problem. Heat is not an issue. The digital vac switch has allowed us to fine tume the switching for the 3rd and 4th motors.

I will post some pics in the near future of the new control panel as we are adding solenoid control to the zone valves and my son wants to do a backlit LED "dash panel"

[tom]

Jr is just like the old man always tweeking something :)

[Gary Campbell]

Tom...
Be nice or I wont help you with the "white box" version of this!!:D

[TravisH]

What SMC digital switch did you use to control this? I would like to try these Lighthouse motors out as well. I have just stumbled upon your utube videos and found you here on the forum. I like to see this information being shared out there for others. Anyways well done on your vacuum. What's the latest report on you vacuum? Are you still happy with it and how are the motors holding up?

Thanks,
Travis

[Gary Campbell]

Travis...
I dont know the exact model, but it does have a NO/NC 24VDC output. They only output 50ma so a small circuit has to be built to operate the relays for the Vacs.

The motors hold up very well. There are dozens, maybe hundreds of us using similar motors. These motors hold up well, even well beyond there published life expectancy as long as they are kept cool.

I am very happy with this setup. All the reasons are listed in previous posts.

[TravisH]

Thanks Gary,

Yes I have enjoyed reading all the other Vacuum posts on these motors. I like the sound of the performance you guys are getting for the price of these motors and seems like a very effective way to go for starting out.

Cheers,
Travis

[frank134]

Gary that all look good. you do some nice work. you also help a lot of us with your ideas. I was wonder if you could share better picture or drawing of your vac box. I like to build one and try to improve my vac system since I now have my link for e-cab. If not I understand.

thank you
frank

[Gary Campbell]

Frank...
Look at the picture in post #8. That shows the end layout of all the components. Motors mount in the center area, intake cooling air comes in the top. Exhaust cooling air exits to the right ans vacuum exhaust exits thru the holes to the left.

The center lower chamber(s) are vacuum, You can see the outline of the partion that is between the pairs of motors.

Most every picture I have has been posted. They should help fill in the details.

[gundog]

Gary,
This is a great system.

I am going to rebuild my very basic vac system soon, new zones control valves PVC plenum Etc. I am moving my air compressor and a new Oneia 3 HP cyclone dust collector system to a small room in the corner of my shop about 10'x8'. I was thinking about moving the vac hold down system to this room also for noise control. I would have to run about 30' of duct to my table manifold do you think this would negatively impact my hold down vac system?

My simple vac system now consists of a plenum with a 4” ABS main run that 2 Vac motors are attached to and 2” feeder tubes to the zones. I have homemade plastic plugs with O rings for sealing the 2” ABS feeding the zones I am not using. The spoil board it just laid on top of the plenum with dowel pins to align the position. It works fine but is a pain to change zones and everything must be blown off real good on both sides of the spoil board to not change the flatness of the table. I have 8” of vacuum using 2 of the motors you used in this project (they run in parallel all the time) when all the plugs are in but I leak a lot around the edges of the spoil board and typically end up with 3”-5” of hold down. I am using a cheap automotive type vacuum gauge for my numbers.

I could see making a system like this one you show in that room and ducting it to the table area. I plan to add a vent to the room or it might blow a wall out with all the pressure. I may also move the intake for the air compressor outside for fresh air.

Thanks Mike

[Gary Campbell]

Mike....
According the the mfgr specs, the LH 7123 flows 75-85 cfm when pulling 5 inHg. By my rule of 1.9 (for parallel/series setups) there would be approx 152 cfm flowing with 2 motors pulling 5 inHg. With a 4" pipe this puts the velocity under 30 ft/sec, which should be reasonable in a pipe of this size. You will experience some resistance and slightly lower performance, but since all of our working conditions are at the above flow or less, I dont see a severe negative impact on hold down.

Guys like Harold Weber (that really know this stuff) can tell you the real deal, but I should be close.

I think you could gain more by adding either a traditional valve system or one like my KISS system ( http://www.shopbotblog.com/index.php/2010/07/the-k-i-s-s-vacuum-manifold/) and gluing your plenum down (and sealing the edges) solid than you would ever lose by relocating the vacs 30' farther away. I tried the loose spoilboard method, and tho it seems to leave more options available to we as machinists, vac hold down suffers greatly. I too, could never stop the leaks due to warped spoilboards and debris.

It looks like a "white box" version of this system will be built for my former machine this winter in the FL Keys. Tom is going to use White PVC Foam board and install the unit outside. We will eliminate some of the baffles as noise wont be an issue in his location.

Your plan sounds good, keep us posted as you build it.

[gundog]

Thanks Gary,
Funny my manifold under the table looks just like that. I left room so I could cut the 2 " pipes when I built it so I could add that type valves later but I haven't yet.

I am going to save your post so I can refer back to it. I was thinking of adding a 3rd motor to the 2 I have now. I may not need it but with your setup they only run when the vacuum drops I really like that idea. I should gain a lot when I redo it and glue the spoil board and seal the edges. My spoilboard edges are semi sealed now I varnished them when I made the system.
Mike

[tom]

Hey gaRy does that box come in white:D: Also I did remember the R












r









r

[frank134]

Thank Gary. I miss post # 8 That help alot. Couple of guess those. Was their any thought in useing the black over the white or is that what you had? The other question. Where did you place the vac switch in your system? I can't seem to see it in the picture. One more. How far do you think I can place the vac unit from the table before I start to lose vac? I want to place it about 20' from my table and thinking of used a 4" trunk line. think that would help?

thank
frank

[Gary Campbell]

Frank...
Black was just the right height on the rack to slide onto the cart and the white had to be lifted. No real reason, as they are the same product. Black box sounds better.

When I installed the analog swith from Joe WW I drillead and tapped a 1/8" pipe thread into the front vac chamber on the side with the relays. Once I switched to the digital I tapped the Vac distribution manifold under the table.

With 4" pipe, I dont think that 20-30 feet would be a problem. Look at post #40 for a little more info

[tom]

by holding Gary's old saw hostage, i got him to come back to the keys and help me with the vac box on his old machine,needless to say it is awsome.Being warm and sunny in s fla.we ran the vac motor box outside now the shop is so quite. Gary just what to say again a big thank you for all your help and knowlege:cool:

[frank134]

Hi Gary….
I just wanted to thank you for the picture of the new vacuum box you built and design. Also thank you for the help you gave me with it. I try making it out of the melamine like you. But I can’t work with that stuff. I made mine out of ¾” birch veneer. I got to tell you it works GREAT. The sound is way down. I think I will just keep it in the shop. The vacuum I can’t get over. I got my vacuum switch in today I can’t wait to install it.

Again Thank
Frank

[Gary Campbell]

Frank...
Glad its working out for you. I agree on the melamine.

One thing to look out for is relay switching current. Many of the digital switches only have 80ma switching current. Make sure yours is below that.

[frank134]

thank gary I will check in that. forgot to show you finish box11778

[Gary Campbell]

Frank...

That looks good! Thanks for posting.

[knight_toolworks]

I just made my two vac box. but i did it out of plywood as it was all I had. I did not use all of the baffles though I wish I had the room to do it. it is more noisy then the feins. they are about 80db and the box is 90db. but I also have twice the vac inches. I will need to hard hose it though the fein hoses want to collapse.

[frank134]

Hi Gary I had a question. Did you put a filter in between your vac table and the black or did you just pipe it stright thru so the dust go thru the vac motor? BY the way It really work great. I still have a hard time beliving how good it work.

[Gary Campbell]

Frank...
No filter installed. Glad its working out for you.

[Gary Campbell]

Guys...
A few notes on this system. Now that I have built, sold and installed a number of these systems, Most are being switched to full manual control.

Reasons are:
1) cost (saves a few hundred $)
2) I have noticed on mine that the vacuum varies much more than I originally thought. From a freshly surfaced spoilboard to 25 sheets into a job I may have almost 2 inHg difference. This moving target of initial vacuum made the hysteresis settings a real pain. In the end, sheets were initially cut with 2 motors and 4 are used to add hold down for the cut thru.

I was hoping to automate this switching, but it appears that either another approach to the control or full manual is the answer.

[jim_vv]

Greetings, Gary

Thank you for this post and for the knowledge that you have shared on this forum. I have gleaned much from you (and all who have contributed).

It has been about eight months since your update and I am wondering if you have any more updated information on how your system is working.

I have been using two Feins on four valved zones for the past several years, but one of them has now melted all of the internal plastic parts for the second time. Rather than the cost of another repair and another failure, I have ordered two LH 6765-13 vacuum motors from Ward and I am preparing to build a two motor box similar to yours with manual switches.

I have read every post that I can find regarding vacuum boxes and have seen two schools of thought regarding filtration on the intake side of the vacuum system. Are you and the others that you have built for still running without intake filtration?

Kind regards,

JIM

[dlcw]

Jim, I built Gary's vac box and put 4 motors in it. They are divided into two chambers inside the box. Each chamber has two motors. Two motors are used to hold 90% of what I cut. The additional two motors can be turned on to increase the CFM to more securely hold the parts when necessary.

I've opted to run mine without input filtration. I have set mine up where I have a simple little desk fan to blow clean fresh air in to the intake part of the box so the motors are always getting clean fresh air. I check the motors regularly to see if there is any dust or debris build up and so far, after about 4 months of running daily, I've had no problems.

Gary did a fantastic job on the design for this box. It works great and my hold down capabilities on my sliding-valve controlled 7-zone table could not be working better. I am extremely pleased with the performance. Even at an altitude of 2500' ASL I still get 7"-8" of vacuum.

[garyc]

Jim...
Along with Don, I have given info to a number of guys that self built, sold a half dozen outright and sold and installed a few more. Other than using a manual switching system instead of the digital switch and relays, no other changes have been made. No changes have been made (by me) on the box design.

So far, no complaints. Mostly good reviews, similar to those by Don. Even better news: No motor failures that I am aware of. Most of my sales have been to commercial shops.

Since 4 of these motors (I used the 240V LH-7123) cost less than a new Fein, consider the advantages of over 400cfm. The 240 V versions use half the amps, have more power and generate less heat. Vacuum is like money; you can never have too much.

I am sure that is not impossible to pick up some debris, but if care is taken to clean the tubing and a fully adhered spoilboard is used, very few that I have seen use a filter. That said, no one could argue that it is a good idea.

[jim_vv]

Greetings, Gary and Don

Thank you for your replies. Gary, I was able to switch my motor order to the 240V LH-7123s. Ward is great to deal with. I am going to build a four motor box with a partition to divide the vacuums into two sets like Don did (no check valve). For now, I will just use two motors as they will provide much more vacuum than I have been using for the past years. When I can afford it and have the time to add another circuit I will add two more motors.

Would ether of you be willing to share or sell your box plans? I understand the pictures that are posted, but I would like some dimensions as your boxes seem to work quite well.

Kind regards,

JIM

[garyc]

Jim...
My plans, which I sent to Don were designed in eCabs and processed as a TWD file thru the SB Link. I havent taken the time to convert them to DXF or PWks files.

[dlcw]

Jim,

I have the check valve in my vac box with two motors in each chamber. 90% of the time I use only two of the motors. I normally switch on the 2nd set of motors (which opens the check valve) when I go to cut through smaller parts. It sticks them to the table like glue.

As Gary said, he sent me the plans from eCabs and I cut the parts through the ShopBot Link. The only thing I can think of would be for you to sign up for eCabinets (it's free), download it, bring in Gary's files, then use them to create the Partworks/Aspire files from the dimensions.

[jim_vv]

Gary and Don,

Thank you. Don, PM sent.

Kind regards,

JIM

[michael_schwartz]

Jim,

I have the check valve in my vac box with two motors in each chamber. 90% of the time I use only two of the motors. I normally switch on the 2nd set of motors (which opens the check valve) when I go to cut through smaller parts. It sticks them to the table like glue.


I am glad to hear that you get by with 2 motors most of the time. I plan to try to nest smaller parts within 24x48 zones, and I am wondering at what point parts become small enough that all 4 motors are required. I am going to start out with the two motors I have.

I don't mind cutting drawer parts on the table saw if I have to. As long as I can hold nested parts larger than 1-2 square feet I will be happy.

[garyc]

Michael...
I dont know if this is the best barometer, but I was able to cut a half sheet melamine of 3.5 x 8 dadoed stretchers without losing any. Only the onionskin pass has the 2nd pair of motors on.

[knight_toolworks]

I am glad to hear that you get by with 2 motors most of the time. I plan to try to nest smaller parts within 24x48 zones, and I am wondering at what point parts become small enough that all 4 motors are required. I am going to start out with the two motors I have.

I don't mind cutting drawer parts on the table saw if I have to. As long as I can hold nested parts larger than 1-2 square feet I will be happy.

if you use a smaller downcut bit is not an issue. I use a 5/32 downcut when am cutting smaller parts. the thinner the material the smaller the bit I use when the parts are small. I can cut a sheet full of 3" circles and not loose one.

[michael_schwartz]

Sounds good. I am pretty excited.

I am going to work on my plenum, and spoil board later this week. I have acquired all of the plumbing.

I bought a 12x24x24 NEMA type 1 enclosure, along with a pair of louvered vents. I am going to mount my motors inside of this enclosure, and mill some flanges from 1.25" thick type 1 pvc to mount to the outside. I got a pair of pvc swing check valves. I should have the rest of the materials for this on monday.

[knight_toolworks]

it's best to have check valves on both sets in case one of the two motors goes out. so you can choose what set you need.
as far as heat it seems the exhaust is hotter from my 220's then my fein type motors.

[dlcw]

I cut 4" coasters (about 230 per sheet) out of 1/4" MDF for a local sports plaque maker and with the new vac setup, I've eliminated having to use any tabs. Off the machine into the customers parts bin. Before I setup Gary's vac box, I always had to use tabs which made for a LOT more work. I've been able to lower my price to the plaque shop because my labor has gone down ALOT. He wins and I win.

[knight_toolworks]

I try never to use tabs they are suck a pain.

[dlcw]

You're right Steve. They are a PITA but sometimes a necessity. Some projects my vac system just won't hold. :(

[knight_toolworks]

using smaller downcut bits or the pressure foot keeps me from needing tabs most of the time. though sometimes it will waste extra material.

[dlcw]

I use the hold down tool on occasion. The only thing I found was that sometimes the chips that are dragged around by the hold down will scratch the surface of my material. I've had this happen a couple of times as the dust collector hood can't be on at the same time as the hold down.

[beacon14]

i'm using two of Gary's original 220V motors mounted to a simple "temporary" plywood box manifold which is connected to my PVC plumbing system (ever since my last Fein gave up). I have the other two motors on the shelf but haven't had time to set up the fancy new four-motor manifold so they are just sitting there as backups right now.

I cut full sheets of melamine and plywood with few problems as long as I take a few steps, like ensuring that no small parts near the edges of the sheet get cut last. I keep small parts away from the edges, make sure the small parts get cut first when there are a mix of small and large parts on the sheet, and try to separate small parts to leave a web of waste around them when necessary.

I also use the two motors to cut solid wood parts down to just a few inches square on a single 24 x 24 zone by nesting them against an "L" shaped fence which is butted to the table stops, covering the rest of the zone with 1/4" one-sided MDF (or anything non-porous), and taping all the seams with blue masking tape. Rigid masking boards work better than plastic sheet to cover the rest of the zone because they provide great resistance to sideways movement of the workpiece. Taping it all together (with the vacuum running) makes the whole thing act as a single workpiece, giving you effectively the surface area of the whole zone to prevent sideways movement.

Using a down-cut bit leaves enough chips packed in the kerf to keep most wood parts from moving or losing too much vacuum, plus it applies downward pressure as it cuts. I can count the number of times I've had to use tabs in the last five years on one hand.

[michael_schwartz]

i'm using two of Gary's original 220V motors mounted to a simple "temporary" plywood box manifold which is connected to my PVC plumbing system (ever since my last Fein gave up).

I can count the number of times I've had to use tabs in the last five years on one hand.

This is really good to hear.

[michael_schwartz]

I also use the two motors to cut solid wood parts down to just a few inches square on a single 24 x 24 zone by nesting them against an "L" shaped fence which is butted to the table stops, covering the rest of the zone with 1/4" one-sided MDF (or anything non-porous), and taping all the seams with blue masking tape..


Thanks. Based on this recommendation, I am going with a 5 zone plenum, rather than 4. I am glad that for whatever reason I bought an extra knife valve. I will add a 24x24 zone.

[beacon14]

Glad to be able to help. Sounds like a good plan.

[sbd1]

Hello everybody. My name is Daren & I'm posting this - my very first post - from my home in western Canada.

First of all, let me say thank you very much to Brady, Gary, David & many others for all the fabulous info you have shared with the rest of us clawing our way up the learning curve. I really admire your commitment to sharing your wisdom, as well as your creativeness & workmanship. I have learned more than just SB stuff from you guys here.

About me. I've had a used, dual-Z, 4x8, PRTalpha for a couple of years, but until recently I haven't been able to spend any real 'quality' time with her. After reading (and re-reading) through this forum for many months (I'm a slow learner) I have started working on my first (and very much desired) vacuum table. I always planned on posting something on the forum someday, it's just that until recently I didn't feel like I understood enough SB terminology to say anything relevant. A few weeks ago I was further inspired by the sense of helpfulness you guys provide in a short Q & A phone call to David about his table design. Now that I've broken the ice here, I hope to be able to do the same as you some day.

I currently have two, 240V, LH7123 vac motors that I'd like to build into a black box like Gary's. I'm not sure yet whether to build the box big enough to possibly expand it up to four motors later, and if I should include a series/parallel valve. I plan on cutting sheet goods in various sizes as well as solid wood parts & I'd appreciate your feedback.

My questions for Gary are:
1) Would you share (or sell me) your black vac box design? I have recently installed eCabs & the SB link trial version, but I have not purchased it. It looks good, but I'm waiting to get more fluent with the SB & eCabs before I invest any more money. I would however gladly accept it from you in eCabs file format (and decipher it from there) should you decide to share it with me.

2) I have read your previous vac motor setup (where you had 2 motors setup with a valve that would switch between series & parallel). But I'm not sure about this black box design. It seems to me like you are only running it in parallel mode. Is that correct?

3) I'm not clear how the integrated check valve works. Could you please explain to me how it operates?

Cheers from frosty Edmonton!
PS. A big thank you also goes out to the ShopBot staff & management who welcomed me with free support when I first called them with my question of "how the heck do I get this to connect with my computer?" This is definitely a business worth supporting.

[garyc]

Daren...
Thanks for the kind word on behalf of myself, David and Brady. Answers to your questions:

1) Yes, I have sent it to others. One note: it requires use of both eCabs and PartWorks to complete as the exact motor geometry was unknown at time of design.

2) This box is parallel only. My testing showed very high temps when connected in series.

3) It is simply a pivoted flapper valve made to mimic the check valve provided to our user group by Brady.

I would recommend using the 4 motors as it will allow you to hold most anything (that is reasonable). Getting the CFM over 400 is the single biggest advantage of this system over most others.

[sbd1]

Thank you for enlightening me Gary.

I think I'll be able to work with your eCabs design. My goal with your drawing is not so much to use it to cut from, but rather as a guide to show me how you directed the airflow. I assume once I see it I will better understand how the flapper valve works. Will you send it to me via email, or is there something I need to do?

I'm glad to hear you think parallel is the way to go, that helps reduce the complexity a little.

[garyc]

Daren..
Send an email to caseworxmfg (at) gmail (dot) com and I will send you the file(s) when I return to Durham.

There is no referrence to the check valve in the files. There is actually more info in the post via the pictures.

[sbd1]

Gary. After looking at your design in eCabs I now understand how the flapper valve separating the two pairs of motors works (doh!). I'm going to build a box like yours (with room for 4 motors) that will allow me to use the 2 motors I have now with a flapper valve & add 2 more later. But I've still got some questions if you're not tired of me yet.

1) I noticed there are a couple of small differences between the eCabs drawing you sent me & the drawing & pics you posted here. I assume the ones you posted here (ie: below) is your revised/preferred design? If so, what is the open cavity used for on the top of the other side? I saw that you used 1 side for the electrical switches.

2) How do you plan to access the motors for service/replacement? Remove an end, then top, then the upper-center fixed shelf above the motors?

3) Do you think it would be beneficial to seal around the vacuum exhaust pipes (through the melamine) with silicone to insure that all of the exhaust is sent out below the box & not coming back into the box? Would it help to keep the motor cooling intake & exhaust air completely separate from the vac exhaust? Perhaps with your open-bottom design this is not important, but I was even thinking that it might be worth adding a vertical, length-wise partition under the middle of the cabinet section to help keep the high-pressure (I assume) vac exhaust from pushing it's way up the lower-pressure (I assume) cooling exhaust.

4) I'm not sure how big of a breaker I need for 4 of theses motors. I believe that they draw up to 6 amps each. So does that mean I should get a 25 amp breaker?

Thanks

[mumeo]

Hello all,

I am also building a box right now, very similar to Gary's design, and thank you very much for all of the information on this forum!

I am putting together a 5 zone system, with a couple of tweaks that I'll detail in the thread I've put together for the build.

http://www.talkshopbot.com/forum/showthread.php?t=14940

For now though, I'm having a little confusion about these vacuum motors...

I see in the black box image that the cooling fans point upward... but where is the inlet for the cooling air? It seems from the picture that that part of the box is completely sealed... is it above? And, is that intake filtered? It seems like it would be a good idea, keep the dust off the cooling fan blades. Maybe with a shopvac filter or something to that effect?

Any help is very much appreciated! Thanks for everything already! :)

[sbd1]

Lucas. As you can see I'm new to this also, but I believe the cooling air intake for the motors comes in at the top of one of the end panels & is filtered. If you look at Gary's photos #1 & 4 in post #2 you will see what I'm referring to.

[mumeo]

Yes, I see now! Thank you Daren.

Bit of a puzzle this one. A fun challenge.

Thanks again!

[garyc]

Daren...
1) The early design had relays, etc for control, which turned out to be costly and didnt work as well as I wished. The latest versions use one side upper chamber for intake cooling air with filter fabric. Other side upper is unused. The cutouts thru the sides are adjusted accordingly.

2) Yes, but to date havent heard that anyone has had to do that.

3) No, they seem to flow just fine AND most importantly keep cool. If you do this post some pics.

4) I have run all that I have installed on 30A breakers.

Lucas...
See Daren's #1 above

[sbd1]

Thanks Gary. I'm starting to get a pretty clear understanding of how your box is designed now. Only a couple questions remain. :confused:

What did you end up using for an air filter in your boxes? I expect it doesn't need to be anything special given that the air is just for cooling the motor. I believe I will also need a filter on the open-air valve in the PVC plumbing, & that one should probably be a bit better seeing as the air goes through the motor. But then again, maybe I'm just over thinking this whole thing & it doesn't matter much either - maybe it's just like my dust collector.

Also, what type of fitting do you use to connect the box to your table plumbing? I'm picturing the box sitting on the floor connected with rigid PVC pipe fittings & then someone walking by bumps the box (or it simply 'walks' a little from motor vibration) causing the connections to break. I'm thinking that you either fasten the box to the floor and/or use some kind of flexible connector.

[garyc]

Daren...
I used a couple layers of spray booth intake (tacky) filter cloth. I have purchased it in the past in 2' by 100' rolls, so I had it on hand.

For the fitting into the box, I used a 3" male threaded adapter glued into the box with silicone. I used a 3" "no hub" connector as a union and vibration isolator between the box and the table manifold.

I used a fully glued spoilboard and never used a filter. But I would never say that using one is not a good idea. Some of the best minds here recommend them.

[sbd1]

Gary,
I've never seen it, but that spray booth filter cloth sounds perfect for the vac motor cooling air via the cutout in the black box.

I'm also going to be using a glued-down spoilboard so no filter there. I was thinking however that I should put a filter of some kind on the open air valve (which I believe should be open when starting the vacs to reduce load?). That spray booth filter should work well for that too though.

That no-hub coupling sounds like a good idea for vibration. I'm planning to use a closet flange screwed & siliconed to the box.

Do you fasten the box to the floor somehow? PL400? Rubber feet?

Thank you

[michael_schwartz]

I chose not to use a filter on mine. The people who recommend them are correct. A dedicated filter is a good idea, if you want to be sure.

I am willing to take the risk, of relying on my bleeder board to filter the air, as a tradeoff for plumbing that may perhaps be slightly less restrictive. This is only a guess.

I did throughly vacuum out my plenum prior to gluing my bleeder board down. I also made sure to clean all debris from the plumbing, during installation. One chunk of loose crud, can destroy these kinds of motors.

I will have to put some spray booth filter cloth over the intake vent on my enclosure.

[jTr]

This is what I came up with, and my gauges show no difference with or without it in line:
http://www.talkshopbot.com/forum/showthread.php?t=14867&highlight=filter

[sbd1]

...I finished my box a while ago & have been happily using it with 2 motors (2 more just ordered). Now I'm finally able to post my version of it here along with some pics of this awesome little vac box. Thanks again to Gary for continuing to answer my relentless questions & for sharing his great design - I recognize that it came from a long road of experimenting & improving. So, in keeping with that development, if I'm able to answer any questions or pay-it-forward somehow to help anyone else, don't hesitate to ask. I'll post pics of my table & vacuum plumbing in other more appropriate threads.

I re-drew the entire box in SketchUp so that I could completely understand how everything worked & fit. I also made a couple of small mods:

1) Added a threaded rod 'indicator' to the flapper so that I could see from the outside of the box, which position the flapper was in. It also allowed me to manually set its position in case something didn't work as planned.

2) Removable top & sub-top panels so that I could access the motors.

3) Removable bottom panel to access the air filter.

4) Homemade air filters to all 3 of the different air intakes.

[sbd1]

5 more pics

[sbd1]

last 5 pics

[pkirby]

I noticed the Lighthouse vac motors require a 1/4" hole (per motor) to allow leakage for proper cooling. Do you guys put (2) 1/4" holes in each chamber of the vac motors or do you put (4) holes in the plenum?

Thanks,
Paul

PS. I just ordered (4) of the LH 7123 :D

[jim_vv]

Greetings, Paul

I used a 1/2" ball valve in the manifold to allow bleed air into the system for the times when I cut material that allows me to get a perfect seal. With a perfect seal, the vacuum drops 1 in.Hg when the bleed air valve is fully opened. I installed a sintered bronze muffler on the valve to help with noise and to ensure that nothing gets sucked in. Most of the time I allow the motors to breathe a little by leaving a gap in the vacuum mask around the part that I am holding. I like the valve idea because, depending upon what I am holding, it gives me the option to leave it closed, open it part way, or open it all the way.

Kind regards,

JIM

[pkirby]

Thanks Jim, I'll try that approach. Where did you get the bronze muffler?

Thanks,
Paul

[jim_vv]

Greetings, Paul

Grainger sells them in various sizes. I used a 1/2" NPT muffler (http://www.grainger.com/Grainger/SPEEDAIRE-Exhaust-Muffler-1A328?Pid=search).

Kind regards,

JIM

[sbd1]

Paul: Good question, I didn't know about that.

Jim: That looks like a good idea.

I believe there's probably enough leakage in my system to equal the flow through a 1/4" hole per motor. Guess I'll know if one of the motors burns out. I do have a separate 2" valve that I open when starting & stopping the motors though to reduce the load at startup.

[pkirby]

Jim,
Thanks for the link.

Daren,
The 1/4" hole per motor is mainly for cooling the vac. I always have wondered if I had enough leakage in my system so that I wouldn't need the seperate holes. I wonder if anybody has figured out how much leakage there is by gauging how strong the vacuum reading is? To better explain... If you have 10"hg of vac and that is the max this motor is capable of, then there would be 0 leakage. But if you're reading 9"hg of vac, then that equates to "blank" leakage? (I'm not smart enough to figure that out:confused:)

[jim_vv]

Greetings,

I used a 1/2" valve because the area of a 1/2" circle is the same as the sum of the area of four 1/4" circles. In may case, I read 11 in/Hg with all motors running, all the zones valves closed, and the with the bleeder valve closed. When I open the bleeder valve all the way I read 10 in/Hg. If my part/sheet hold down is leaking and I read 10 in/Hg then I don't open the valve because I figure the motors are getting a little air which appears to be a loss of 1 in/Hg. Not very scientific, but it seems to work for me.

Kind regards,

JIM

[pkirby]

Good idea Jim. It may not be scientific, but it seems perfectly logical to me:)

[larry_k]

Hi ,I would like to make my first vac table. I love the black box that has been made. can any one send me the files. thanks alot larry
kilian55@comcast.net

[QUICK-BURN]

I am also working on a vacuum enclosure for up to 4 Litehouse motors, Daren and Gary would you be willing to share your 3D CAD designs with me? I'm going to run a CFD on my enclosure when it is complete and make sure there arent any unneccesary restrictions and will be more than willing to share my completed design.

[garyc]

Richard, et al....
I only have eCabinets files for this project that are incomplete at best. It was a project that in the long run, turned out to perform much better and run quieter and cooler than even I had expected. Even though I had made, sold and installed a number of these systems for profit, I decided that the ShopBot community could benefit from the design so I put all the info I have on the forum to allow it to be open source.

I would be open to assisting someone that wanted to take the design and turn it into PartWorks compatible vectors to share with the ShopBot community. (improvements welcomed) Even more so with someone that would accompany the vectors with some written instruction and/or explanation. With that said, I would NOT be open to those that wanted to profit from my original design. This "open source" vacuum idea was born with a thread started by Brady Watson and only contributed to, albeit with a few variations, by me.

This design is my intellectual property, and I have given it freely to this community for non-commercial use. Permission for commercial use of the design has not and will not be given.

Daren seems to have made a great start to my intended end, maybe he can be convinced to bring the project to the next level.

[pkirby]

Gary,
I've bought all the parts for the build, but haven't had time to build it yet because I've been so busy with work. I would be more than happy to make a full set of partwork files for it to share with the community. To build off your plans, the only thing I would need is a drawing with dimensions or dxf/dwg and then I can convert everything to partworks.

Thanks,
Paul

[sbd1]

I am happy to give back to this community Gary, thanks for asking.

I agree with Gary about the limits of this information that we're sharing (ie: non-commercial use, etc...) and have added those notes in my file. Here is a DXF file that can be imported as vectors into your choice of CAM software for your final touches. It does not contain step-by-step instructions or a complete materials list, but that info can be easily acquired from this forum.

Cheers

[garyc]

Daren...
Thanks a lot for taking the time to post this.

[crash5050]

Has anyone made any progress on making the partworks files? I tried, but without the dimensions it is going to be hard to do.

David

[srwtlc]

David, scroll/down up to post #104. ;)

[crash5050]

Yeah, I got the dfx file, but how tall what lengths, dimensions are the sizes of each part. Those are not there. Besides, it doesn't matter. I qjust guess CNC work is not for me, I am going to haul the thing to the scrap yard!

[sbd1]

David, this stuff can be really frustrating - believe me, I know!

The DXF file I uploaded of the vac box is to scale, so you should be able to import it into your design software & the parts should be the right sizes. Here's the dimension of one item so you can confirm it. Hang in there, it gets easier...or so I'm told.

Speaking about frustration: I believe that allot of this software is amazing in many ways, but some of it (eg: eCabinets & ShopBot Link) seems intentionally difficult to work with. It's impossible for me to believe that anyone could actually be very productive with it. I guess that's where the value of good software really is. I used to work with a company that used good software, but never really appreciated it until now that I can't afford it. Someday perhaps.

[crash5050]

Daren,

Thanks, that makes sense now. Since they are to scale I can get them into Aspire.

David

[jerry_stanek]

Daren,

Thanks, that makes sense now. Since they are to scale I can get them into Aspire.

David

All you have to do is open it in Aspire and delete the arrows you will have to join the sides also

[sbd1]

One thing that may not make sense to you when looking at the vectors would be the exhaust holes in one of the panels. That's because I drew them as angled cuts going through the panel. You'll have to clean these up a little before cutting.

And like Jerry said, just move my notes & lines to another layer so they won't get cut - or delete them.

[crash5050]

I would appreciate any positive or negative feedback on the way I have drawn this in aspire. I used Daren's dfx file, and attempted to toolpath it somewhat like the poictures of Gary's Box. Please feel free to make adjustment's or use this as a template for your own box.

David

[Joe Porter]

David, I am not sure I know what I am looking at, am pretty low on the totem pole around here as far as computers and proramming, etc. However, I did notice that you have tiny little tabs holding your parts in place and only one for each part. With no vacuum as yet, I would make my tabs at least .75" long and .25" thick and add several of them to each piece. I you use 3d tabs, you might make them .5" thick. Just my humble opinion, ....joe (would show a smile here, but don't even know how to do that!)

[crash5050]

like this :)

[Joe Porter]

Yeah, but when I try it, all I get is a :). What am I doing wrong??? joe
Well, It worked!! When you hit submit, then it makes the smiley face...joe
Now, I am complete!!

[Crafted Ingenuity]

Quick question about the litehouse motors... is there any reason why you would use the LH7123-13 motors as Gary uses opposed to the LH6765-OD 240 volt that is on the same page that Gary links to at the beginning of this thread? Beyond that they are not flat bottomed they seem that they would have more suction value to them.

Thanks!

[garyc]

Jason...
The do have more suction, but due to the non flat bottom and overdrive, I selected "the ol standby" (LH 7123) If you buy them, let us know how they work. :)

[Crafted Ingenuity]

Jason...
The do have more suction, but due to the non flat bottom and overdrive, I selected "the ol standby" (LH 7123) If you buy them, let us know how they work. :)

Wow that was a fast reply!
Thanks Gary, appreciate it! And thanks for a great thread too with all your helpful insights and pictures along the way :)

[JDGJr]

http://www.talkshopbot.com/forum/showpost.php?p=134477&postcount=91

From post #91, how was the switchbox attached to the metal frame?

Thanks to Gary and everyone who contributed to this thread - I think this will do great towards lessening the noise in my shop. Can't wait for the motors to arrive so I can get this thing on-line.

John

[sbd1]

John, the switchbox is screwed to the underside of my table (MDF painted blue).

[crash5050]

I finally got the box cut out, flip op and all, tomorrow I will begin the assembly. I am going to assume that the joints are glued and brad nailed, and possibly some silicone to prevent leakage?

David

[JDGJr]

I hooked my new vac box to my table last weekend and ran it briefly to make sure it worked, and thought I liked the sound level.

Today, I finally got around to cutting with the vacuum on, and it has a very annoying variable vibration, with a frequency around .7-.9 hertz. I can feel the vibration when touching the box, and the pulsing sound gets annoying fast. This is with 2 of the 4 motors running.

Has anyone had this, and corrected it? I may disconnect all but 1 motor and see if that makes a difference. Any other ideas?

thanks,
John

[donek]

I hooked my new vac box to my table last weekend and ran it briefly to make sure it worked, and thought I liked the sound level.

Today, I finally got around to cutting with the vacuum on, and it has a very annoying variable vibration, with a frequency around .7-.9 hertz. I can feel the vibration when touching the box, and the pulsing sound gets annoying fast. This is with 2 of the 4 motors running.

Has anyone had this, and corrected it? I may disconnect all but 1 motor and see if that makes a difference. Any other ideas?

thanks,
John

It sounds like harmonic beats. This is what happens when you have tones that are very slightly out of tune. If you run two vacs at the same time, this will frequently happen. When tuning a musical instrument, you listen to the beats and adjust your tuning to make them go away. You are getting these beats because of minute differences in the two systems. It could be a slightly different shape to one vac impeller or one zone is not sealed quite the same as the other. If you wish to learn more about this, you can look up constructive and destructive interference.

[JDGJr]

Thanks Sean.

I will do some experimentation with different pairs of motors.

Is it likely this is directly caused by the motors, or could it largely be the cabinet reacting to them? Dunno exactly how to word the question, and sure don't know how to prove the cabinet is the main cause.

[donek]

Thanks Sean.

I will do some experimentation with different pairs of motors.

Is it likely this is directly caused by the motors, or could it largely be the cabinet reacting to them? Dunno exactly how to word the question, and sure don't know how to prove the cabinet is the main cause.

You can easily confirm it. Below are a couple of images.

http://static.ddmcdn.com/gif/butterfly-color-interference.gif

http://upload.wikimedia.org/wikipedia/commons/2/2c/Two_sources_interference.gif

http://emfsafetynetwork.org/wp-content/uploads/2011/11/interference.jpg

You'll that there are regions of darkness in the third image as well as the second. Just like these images indicate, you'll find zones where you can not hear the beats and others where you can. It is not likely do to your enclosure. We do not use an enclosure on our vacs and can frequently hear beats. Usually when we have 2 vacs of similar age or use. As one is used more and more, it's tone becomes so out of tune with the others that they are no longer close to the same tone.

[JDGJr]

thanks again.

related to phase: should both of my 240V motors be wired the same, or should one have the 2 hot wires reversed? Currently they are wired the same.

[Josh Beckmann]

I just purchased a 5 x 10 machine. Gary, can you suggest the number of motors I should use for it?

Thanks!

[Gary Campbell]

Joshua...
Depending on how efficient your system is and what size your parts are, 4 should do the job. With that said, my usual rule of thumb is to use 1 motor for each 2 by 4 zone (8sqft). That rule would require 6.

The old system, with many variations shown on this thread, may require 6 to deliver the same performance that the new design does.

New design here: http://www.usroutertools.com/black-box-vacuum-systems-s/339.htm

[Kyle Stapleton]

Has anyone bought a black box vac from the website?

[rookieatbest]

Does someone have a wiring diagram on how to connect the relays to the vacuum switch and motors?
I have the relays and motors on order but what adjustable vacuum switch regulator is recommended for the 4 lighthouse motors. I plan on running 2 motors and regulate the other 2 to turn on like the original design by Gary.
Thanks

[aschutsky]

Awesome post! Any new success stories to share? Looking like I will be building one of these guys in the near future once my bot has arrived home. Huge thanks to Gary, Brady, and Daren! DXF files look great and very helpful. :)

[Gary Campbell]

Thomas...
If you look at Thread page #2, Post #53, I posted that in the long run, and mostly due to weather and spoilboard condition, the "automatic" switching of the second set of vac motors was determined as being very unreliable. I suppose with a digital vac switch and a small processor, you could make a system that followed the moving target of initial vacuum setting. As stated there, the vast majority have either built with, or switched over to manual second stage vac switches.

Good luck & post pics when done.

Andrew..
You are welcome, but I had the easy part. Those before me laid all the groundwork.

[TheSniper]

I am happy to give back to this community Gary, thanks for asking.

I agree with Gary about the limits of this information that we're sharing (ie: non-commercial use, etc...) and have added those notes in my file. Here is a DXF file that can be imported as vectors into your choice of CAM software for your final touches. It does not contain step-by-step instructions or a complete materials list, but that info can be easily acquired from this forum.

Cheers

All,
I know this thread has been going on for awhile. I have Dl'd the DXF file on several diff machines Mac and Windows. it claims to Dl okay. but opening it says its not an Acad file. help?
As far as my app is concerned my error is
"dxf is not valid DXF file
Invalid or incomplete DXF input -- drawing discarded."
-S

[TheSniper]

says its not an Acad file. help?
As far as my app is concerned my error is
"dxf is not valid DXF file
Invalid or incomplete DXF input -- drawing discarded."
-S

All,
After many attempts to open the file. seems like renaming it from a DXF file to a DWG file did the trick.. odd but it worked. So cry for help averted!
-S

[aschutsky]

A few questions for the experts - ;)

-For the sake of simplicity, if one already has a shopbot with a 4 zoned 4x8 table, would it be easiest just to plumb one lighthouse motor directly to each zone? I realize that more holding power would be realized combining motors, but would this be needed for each 2x4 section? I'd likely not be cutting anything smaller than 12x24", and even then I could use masking panels to minimize leakage, correct?

-I've read through this thread a few times but I'm new to all of this and I'm a bit dense. :p In the original blackbox design, do all of the motors run in parallel?

Many thanks,
Andrew

[aschutsky]

Ugh, a few more since I can no longer edit - :)

-In the original design, my understanding is the check valve is used to keep the pairs of motors from fighting each other. Are these implemented at each zone right before hooking to the table? Brady's pictures in page 3 appear that is the case, but I wasn't totally clear.

-Does anyone have a good, clear picture of how the motors can be hooked together in series? I'm an electronics guy and the definition of series/parallel is clear to me, just want to visualize how the same is done in terms of the plumbing.

[Brady Watson]

I'm pretty sure serial setups are frowned upon by Lighthouse/Ward at this point. Parallel is the way to go if you want them to last. Just throw all the motors in one box to maximize airflow - then plumb from the box to your zones.

-B

[aschutsky]

I'm pretty sure serial setups are frowned upon by Lighthouse/Ward at this point. Parallel is the way to go if you want them to last. Just throw all the motors in one box to maximize airflow - then plumb from the box to your zones.

-B

Thanks Brady. If all four are always running is the check valve still needed? Anyone here using any type of a filter to prevent debris from entering the motors?

[jerry_stanek]

If you use a spoil board there is nothing that will get sucked in

[Brady Watson]

You don't need a check valve on any motor for it to be an ideal setup. My 'Ova da hump' valve concept is for high Hg" vacs to be used in conjunction with high CFM/Low Hg" to get over the hump & start building negative pressure with the little pump. It is mostly for guys with pucks, vacuum bagging or vacuum forming.

You should most definitely run filtration on those motors. An automotive air filter or cylindrical shopvac filter (Rigid brand ones work well) to keep anything the bleeder misses or chunks/debris when you first fire up your system. Also, put a little filter/breather on your bleeder holes for the vac cooling holes so that junk doesn't get into the pump that way. Cheap insurance...Few even think about the little PVC chips that are stuck to the inside of pipes when you cut them while plumbing the system the first time...

-B

[aschutsky]

Thanks Brady. I think I've got a good grasp and was probably over thinking the setup before. Let me get my machine and dust collection set up and I'll be on to building this.

If anyone has ideas for an inline filter that would work with a ~3" inlet/outlet, feel free to post them up. :)

[nambass]

Guys, I am new to this, but am trying to configure my vacuum table. I have a 1 mand cabinet shop and the size of my table is 2m x 3m. I just orderd 4 lighthouse pumps from Ward and he recomended I talk to you guys. I really liked the black box as was and the QUAD setup. My question is simple. I need to be able to get the max suction, and also do not even know the best way to connect the 4 pumps. Can you provide me some diagrams to help me with this - Will really appreciate this!

I usually cut 12mm MDF with a single cut, but then from time to time also have smaller peaces I cut such as 3mm MDF. The MDF sheet size is 1.7m x 2.8m

[pkirby]

I'm about to wire up my (4) LH7123 motors and was wondering if someone could double check my wiring diagram that I plan on using? I'm going to add this indicator light (https://www.carltonbates.com/Indicators/SOLICO/Indicating-Light-Green-Neon/3052-3-11-38340/p/78966098732-1) for a couple of reasons. One is to make sure a fuse hasn't blown and the other reason is that it will give me a visual indication when the vacuum is running. Please let me know if you think this setup will work. Thanks.

20408

[MsandersW]

I'm putting together a vac box following the work outlined in this thread. I was discussing it with an electrician friend and he asked about thermal overload protection. I assume with these "replacement" motors this is handled with the rest of the electronics and housing the motors go into. In the application outlined here I'm curious what are others doing to add thermal protection to the individual motors.

The only mention I have found was in another thread where someone used Lighthouse motors and mentioned "having their electrician install thermal protection" before the thread died out.

Thanks in advance for any help with this question.

Best,
Mike

[David Iannone]

I'm pretty sure serial setups are frowned upon by Lighthouse/Ward at this point. Parallel is the way to go if you want them to last. Just throw all the motors in one box to maximize airflow - then plumb from the box to your zones.

-B

My two motors are on the way from TN. Going to depot tommorrow for pvc and plywood. I have read so much on this forum about vacuum hold down, and I just got to give it a try.

[Brady Watson]

Nice! Make sure you add a filter...:)

-B

[barrowj]

David,

My 2 motors were shipped Thursday or Friday from TN also so should be here today or tomorrow. Also called Ward to say I forgot to mention the gaskets and he had them added before shipping. I will be getting my plywood and pvc by this weekend, just too much going on to get it sooner. I have pulled down everything from this thread w/pics too to try to put it all together prior to heading the HomeDepot. Will take pics and post as I get going.

One question, to clear up the confusion, what is the actual recommendation of cutting the zones, I'm assuming the 1"x1" grid? How are they gluing the bleeder board down, by that I mean if you are using the grid, what part is being glued. I hope this part doesn't sound too stupid but I always was under the impression that you just layed the bleeder on top of the grid, is the bleeder board also the spoilboard? I will be sealing the edges.

Thanks for any help with this.

Joe

[David Iannone]

Joe,
I am doing the 1"x1" squares. But I have seen some that have done slightly different patterens or grooves throughout the plenum. I think it is all about air moving, could be circles I guess? As far as the bleeder board, it looks like you skim a little off side number one, then glue it down to the plenum. From what I have read here on the forum I think the best way would be to glue all around perimeter and in between the zones. (That is the way I understand it.) Then skim a little off the top side and ready to go.

My plan is this:
I have just redone my table base last week. I took it back to the stringers and started with a 3/4" MDO bolted to frame. Then added Rockler ttrack and screwed it down. Then glued down 3/4" MDF in between the tracks and skimmed .005 off the surface until flat.

Now, for my vaccum. I plan to build a box, cut one hole in the far end of my table for the PVC, and make a BradyVac one piece drop on board. I am keeping it small for my first try with vaccum hold down, After I work out the kinks, I will then probably make a 4'x4' Plenum and bleeder board for the far end of my table that will stay on the table most of the time.

I rarely cut things over 4'x4' so I figure most of the time I will have all the options available. Working on setting up Jigs, gonna start zeroing off my limit switches with custom c3 comands. I am trying to stop running my Bot like a cave man.....LOL

Dave

[David Iannone]

My new table base finished last week.

[Tim Lucas]

David,

My 2 motors were shipped Thursday or Friday from TN also so should be here today or tomorrow. Also called Ward to say I forgot to mention the gaskets and he had them added before shipping. I will be getting my plywood and pvc by this weekend, just too much going on to get it sooner. I have pulled down everything from this thread w/pics too to try to put it all together prior to heading the HomeDepot. Will take pics and post as I get going.

One question, to clear up the confusion, what is the actual recommendation of cutting the zones, I'm assuming the 1"x1" grid? How are they gluing the bleeder board down, by that I mean if you are using the grid, what part is being glued. I hope this part doesn't sound too stupid but I always was under the impression that you just layed the bleeder on top of the grid, is the bleeder board also the spoilboard? I will be sealing the edges.

Thanks for any help with this.

Joe

Hi Joe,

I cut mine at 2" squares but you can cut 1" - the bleeder is the spoil board - I took someone else's advice from this forum and used silicone to glue the bleeder down around the outside edge and between partitions - Hope this helps
Tim

[Kyle Stapleton]

Here are some pictures of when we setup ours
http://www.talkshopbot.com/forum/showthread.php?t=19117
post #2
We just used the stock files from Shopbot.

[barrowj]

Thanks Tim, think I will do that, just silicone the edges and between the zones. I will also seal the edges too.

Kyle, thanks for the info.

Everyone has been more than helpful and I really appreciate it.

Joe

[David Iannone]

Here are some pictures of when we setup ours
http://www.talkshopbot.com/forum/showthread.php?t=19117
post #2
We just used the stock files from Shopbot.


Great re post Kyle. I have read over your setup pics a few times at least. Wish CNC training training was offered when I was in school. You are doing an awesome job.

Dave

[MechanoMan]

The vac source consists of 4 Lighthouse Brand LH-7123 240V motors. These are 10.4 inHg/110 cfm units each. Combined they should pull close to 10 inHg and have close to 400 cfm. Testing has shown this to be a very powerful vac source, and holds over 9 inHg when applied to less than the full 4 zones.

OK, I know this was in 2010, but someone help me out...

The performance of that motor is listed on the XLS here:
http://www.centralvacuummotor.com/lighthouse.htm

7" static is 95" H2O and that motor is rated to move 35 CFM (per motor).
9" is 122" H2O and that motor moves about 13 CFM.

But the 110 CFM free-air rating shouldn't be relevant. Whether or not there's plywood stock covering the bleeder board, the bleeder board is going to make a lot of static pressure drop.

What's the size of the "less that the zones" that this measurement was taken under?

BTW, the check valve thing sounds like an issue. A check value by nature requires an actuation pressure differential. And that pressure differential doesn't go away once it opens- the ongoing pressure difference is what makes the force that keeps it open. The thing is, of course, that pressure differentials are the entire product here, and difficult to achieve in the magnitude we want. So... it's eating up some of the performance.

[Brady Watson]

You would need some pretty sophisticated instrumentation and time/testing to fully answer all of your questions. Vacuum is not always easy to quantify in terms of what is actually going on, especially since in the practical world of CNC routing, things are not always linear.

One possibility regarding less than 4-zones, could be that there is enough leakage (and there should be SOME for cooling of these motors) to move the working vacuum characteristics into a different area of the compressor trim map. This is akin to a turbocharger compressor map - and while ideal is linear, actual is not. Plus, unless you are running a completely sealed setup with gasketing, there is going to be some leakage, such as around the table perimeter, or if you didn't do such a hot job with the plumbing.

Static CFM is very much relevant during the initial suck down when the pump is beginning to build negative pressure - aka getting over the hump. For example - you may have one of these motors capable of 100 CFM static and an air conditioning pump that only pulls 5 CFM, but maxes out at 27 Hg". That pump will NEVER build vacuum without properly sealed and gasketed fixturing. It just doesn't have enough CFM to seal things off. This is where a check valve makes sense in conjunction with a high CFM vac - especially if you are doing something like vacuum bagging. Big CFM vac to remove most of the air; small high suction vac to pick up where the big CFM pump left off. Neg pressure pulls the valve shut & big vac can be turned off.

The thing to remember with these vacuum systems is that they are designed to be a shoestring solution to more expensive vacuum pumps. The original idea was to employ these bargain setups and make some money until you can afford a proper commercial/industrial grade setup. Some users don't have 3 phase or simply can't afford (or don't need) a pro setup - so certain provisions and allowances have to be made...as in, 'you get what you pay for' & 'everything has a price'. So...some questions probably cannot be answered without either paying someone to do the research/study or you have to do this sort of thing yourself.

-B

[MechanoMan]

Hmm I think it may boil down to this-

With a well-designed bleeder board, how many inches of vacuum is required to get a useful holding force on a small object, and how many CFM per sq ft will occur at that pressure?

Now the CFM situation drops when you throw a whole sheet on it and vacuum increases its hold. But once you're talking about a whole intact sheet the holding force is absolutely tremendous and holding is not a problem if you could hold a small object. The ability to hold a small object drives the specification for the job.

I don't know what the most practical spec to set up for a small-object is. Like I could ask "can I cut out a 3" circle from a 5" square of plywood and have it stay in place?" But then again if I didn't have vacuum table I probably would never try to use Raptor plastic nails to secure a little 3" circle, I expect a person would leave it tabbed together and break it out later.

The inches of vac needed to hold a small part should be the same whether the rest of the zone were covered or not. The question becomes whether that inches-of-vac spec can be met under the CFM flowrate of a mostly uncovered bleeder board zone. Which can readily be predicted by blower spec sheets if there's a spec for what CFM-per-sq-ft should be through a bleeder board at the minimum static pressure spec for holding small objects.

[bobmoore]

An interesting study Mechanoman. Please keep up the study and post your results. I used to run a plant with komo routers with 40 horse becker vacuum pumps and we would never have dreamed of trying to run a 5" square with a mostly uncovered spoilboard. Becker pump could pull nearly 27" of mercury. I don't remember how many cfm but it was substantial. Bob

[Brady Watson]

An interesting study Mechanoman. Please keep up the study and post your results.

I would also like to hear what you've discovered about this. BTW, welcome to the SB Forum. Most of us go by a first and last name basis. Feel free to introduce yourself. I know a few SBers down in your neck of the woods.




With a well-designed bleeder board, how many inches of vacuum is required to get a useful holding force on a small object, and how many CFM per sq ft will occur at that pressure?


You have to run some calculations. There isn't a hard and steadfast yardstick because many variables are at play; such as: tooling geometry - is the cutter defeating hold down with upward helix/lift? What is the chipload and in turn, the amount of force being exerted upon the workpiece? Does the bleeder board have shallow kerf marks in it coincidental with the current toolpath (you cut a sheet of circles with freshly flattened bleeder...now parts don't hold on your 2nd sheet) ? There are other things too.

In an ideal world, CFM would equal 0 or very close to zero when holding down a given part. However...this is hard to quantify since the first part that is completely cut out of a piece of material has full vacuum force holding it down - as the kerf starts to bleed out (or in), suction is reduced and airflow increases. This is with a bleeder board...not a gasketed setup.

So...Surface area is going to be the yardstick here. If you have a vac capable of delivering a solid 9 Hg", then you'd be a little more than 1/3 atmospheric pressure, 14.7 psi, so we'll say 5 psi. Can your surface @ 5 psi total resist the force of a cutter going XY,Z speed at fC (ChipLoad)?

It's not the pump that is the most important...It's how you use what you've got. I've seen plenty of shopvac setups trump industrial pumps in their usefulness because the operator knew how to use the vacuum he had at his disposal. Universal bleeders are not the end all be all. They are meant to be a 'throw a lot of vacuum and airfow and see what sticks' solution. They waste so much energy compared to a puck system with gasketing and a smaller pump - provided the material isn't too porous...but they sure are convenient if you mainly do full sheets.

It would be lovely to quantify vacuum and say for sure what will and won't work. When it gets down to the nitty gritty, there's too much room for variation. So I'm afraid for now, the best we can do is guesstimate, take our own readings and do our own testing in our own shop. Something as simple as a material vendor (such as Trupan UL vs Sierra Pine) could mean a substantial difference in performance with identical hardware...so like most other things in life, YMMV.


-B

[MechanoMan]

Yet one should not throw up one's hands and declare it incomprehensible because the problem has variables and variable standards.

Clearly there's a wide variation in the achieved vacuums people have worked with. It'd be good to know what people found a useful minimum. Are we saying 9"Hg as a minimum to get "basic" results?

Hmm, how does this work exactly? See a bleeder board might lose 80% of its thickness before being replaced. When "new", a high vacuum underneath doesn't mean high holding force on top. If you fail to resurface the sealed faces of the bleeder board, you develop high vacuum but no CFM.

Conversely, if you had a perforated (drilled-through) conventional vac table, but only used a fan with low vacuum, you could see some high figures for CFM, but this wouldn't equate to holding force.

I'd think "vacuum at the workpiece" would be the appropriate figure, however, there is no appreciable pressure drop at the open surface for a Trupan bleeder board. Or a perforated board, either.

I think what we're looking for is a SEALED surface pressure drop. That is, you have a cup with a rubber seal on the rim, and stick it on the table. How much pressure drop is there in the cup? That should dictate holding force. If you have a low-porosity bleeder board that you failed to surface, you would develop "impressive" vacuum underneath but the lack of vacuum on top would be apparent. Similarly, if you had a perforated bleeder board and didn't cover the unused holes, you get impressively high CFM but again the surface cup test shows the low vacuum pressure indicating poor performance.

The cup would need to be large enough that the sideways leakage- CFM- under the seal does not relieve the generated vacuum. That sort of leakage is going to happen even if the seal were "perfect" and the cup was glued to the board, because the bleeder board is porous by nature.

Yes of course cuts in the surface from prior use will mean you have greater pumping requirements until resurfacing. I do see that. But the test would lead to a proper understanding of the design requirements.

For example, I'd like to be able to know that "for a standard 1/2" Trupan board, properly faced, you need X inches of static underneath, which loads down the pump with Y CFM per sq ft. This will allow you to cut a 1 ft diameter circle of plywood with a 1/4" bit of a certain type at a certain depth-of-cut and IPM".

From there a person could say "I have an impressive 5HP spindle and want to cut faster" or "but I need to cut smaller parts at the same speed" and be able to calculate what the vac pump requirements are to achieve a solid hold under different side forces.

Just, not this guesswork thing. So far I've seen anecdotal accounts going all over the place.

[Chuck Keysor]

Hello Mechanoman. I would like to mention that I agree with Brady's statement: "BTW, welcome to the SB Forum. Most of us go by a first and last name basis."

This is a very friendly forum, and I think part of it is that people use their real names. I am involved in other forums where pseudonyms abound, and my personal observation is that things don't stay as friendly when people are anonymous. Do what you want, but I hope you will consider using your real name.

Thanks, and welcome aboard, Chuck

[Justin G]

Yet one should not throw up one's hands and declare it incomprehensible because the problem has variables and variable standards.

Clearly there's a wide variation in the achieved vacuums people have worked with. It'd be good to know what people found a useful minimum. Are we saying 9"Hg as a minimum to get "basic" results?

Hmm, how does this work exactly? See a bleeder board might lose 80% of its thickness before being replaced. When "new", a high vacuum underneath doesn't mean high holding force on top. If you fail to resurface the sealed faces of the bleeder board, you develop high vacuum but no CFM.

Conversely, if you had a perforated (drilled-through) conventional vac table, but only used a fan with low vacuum, you could see some high figures for CFM, but this wouldn't equate to holding force.

I'd think "vacuum at the workpiece" would be the appropriate figure, however, there is no appreciable pressure drop at the open surface for a Trupan bleeder board. Or a perforated board, either.

I think what we're looking for is a SEALED surface pressure drop. That is, you have a cup with a rubber seal on the rim, and stick it on the table. How much pressure drop is there in the cup? That should dictate holding force. If you have a low-porosity bleeder board that you failed to surface, you would develop "impressive" vacuum underneath but the lack of vacuum on top would be apparent. Similarly, if you had a perforated bleeder board and didn't cover the unused holes, you get impressively high CFM but again the surface cup test shows the low vacuum pressure indicating poor performance.

The cup would need to be large enough that the sideways leakage- CFM- under the seal does not relieve the generated vacuum. That sort of leakage is going to happen even if the seal were "perfect" and the cup was glued to the board, because the bleeder board is porous by nature.

Yes of course cuts in the surface from prior use will mean you have greater pumping requirements until resurfacing. I do see that. But the test would lead to a proper understanding of the design requirements.

For example, I'd like to be able to know that "for a standard 1/2" Trupan board, properly faced, you need X inches of static underneath, which loads down the pump with Y CFM per sq ft. This will allow you to cut a 1 ft diameter circle of plywood with a 1/4" bit of a certain type at a certain depth-of-cut and IPM".

From there a person could say "I have an impressive 5HP spindle and want to cut faster" or "but I need to cut smaller parts at the same speed" and be able to calculate what the vac pump requirements are to achieve a solid hold under different side forces.

Just, not this guesswork thing. So far I've seen anecdotal accounts going all over the place.

Ah, yes. Science! This is a great question about required hold down force for a a given chipload. I hope you can come up with a table or chart that clarifies this.

[allen00se]

just a quick question...

I am planning on building a 2 motor box where I can use 1 motor at a time. If I am only running 1 motor, what is keeping the running motor from pulling air through the idle motor? Is that what the check valve is for? I have seen plenty of pics of the actual box but have yet to see a "plumbing" diagram.

Thanks in advance.
Krys

[kenkelsey]

I just built the 2 motor version of the BB. I have it plumbed up, but I am still working on the table plenum and positioning of the 2" holes through the table. Based on just a feel test (hand over the vacuum intake at the table, I don't believe one motor will pull enough vac. From my unscientific test, I would say that one vac motor has less vac pull than a 10 gallon shop vac. I did have the same idea as you about using one motor, but I'm now doubting that. I will be up and running in a couple of days and will post my experience. I do have a vac gauge on order for more measurable results.

[David Iannone]

just a quick question...

I am planning on building a 2 motor box where I can use 1 motor at a time. If I am only running 1 motor, what is keeping the running motor from pulling air through the idle motor? Is that what the check valve is for? I have seen plenty of pics of the actual box but have yet to see a "plumbing" diagram.

Thanks in advance.
Krys

Welcome,

Here are a few pics of my plumbing. Pay no attention to the shopvac filter and 8" PVC. I ran out of room plumbing and am doing a different type of filter. Trying to work on finishing mine this week. The fun part to me was working without a diagram.....(on the plumbing that is) all I did is just looked at my machine and figured out where I thought I wanted to turn on vac box and open/close valves and started cutting and gluing.

P.S. When you build your box, don't forget to seal the vacuum chamber. I forgot to do that and still need to take my box back apart and do that.

Dave

[kenkelsey]

I did finish my plumbing and fired up the black box last evening. I placed a a 3 foot square sheet of aluminum directly on the plenum (no spoil board). Using only one motor in the BB, the sheet was not securely held in place. With both vac motors running, the hold down was solid. Not sure what the result will be when I install the spoil board, but I'm pretty sure that running only one motor in the BB will not be sufficient for most applications.

Your installation looks great.

[allen00se]

I did finish my plumbing and fired up the black box last evening. I placed a a 3 foot square sheet of aluminum directly on the plenum (no spoil board). Using only one motor in the BB, the sheet was not securely held in place. With both vac motors running, the hold down was solid. Not sure what the result will be when I install the spoil board, but I'm pretty sure that running only one motor in the BB will not be sufficient for most applications.

Your installation looks great.

This actually makes me nervous to hear, I would have expected these vacuum motors to be more powerful than your average shopvac. Interested to hear some results with a a vacuum gauge hooked up.

[allen00se]

I just built the 2 motor version of the BB. I have it plumbed up, but I am still working on the table plenum and positioning of the 2" holes through the table. Based on just a feel test (hand over the vacuum intake at the table, I don't believe one motor will pull enough vac. From my unscientific test, I would say that one vac motor has less vac pull than a 10 gallon shop vac. I did have the same idea as you about using one motor, but I'm now doubting that. I will be up and running in a couple of days and will post my experience. I do have a vac gauge on order for more measurable results.

So I was getting worried about this and just googled some performance info on a basic shop Vac
8 Gallon 4.5HP Shopvac
Air Flow: 175 (CFM)
Sealed Pressure: 60 (inches)
Electrical Ratings: 120V 60Hz 9Amps
Peak Air Watts: 320

Compare that to the Motor from the first post
LH7123 240v
Stages:3
AirFlow: 552 (CFM)
Sealed Pressure: 148.8"
Amps: 7.0

Looks like you either aren't using the LH7123 240V, or you have one hell of a shopvac.

[kenkelsey]

I do not have my vac gauge yet, but others using the same black box configuration have reported 8 inches with the recommended vent hole open and up to 10 inches closed with two motors. I do not know what shop vacs pull in inches, but mine is at least as powerful (if not more than) two LH 220v vacs. I should be in operation tomorrow. Sealed the plenum tonight and putting the new spoil board in place tomorrow. Will advise how it well it holds various materials over the next week. CFM is also an important.

[allen00se]

I do not have my vac gauge yet, but others using the same black box configuration have reported 8 inches with the recommended vent hole open and up to 10 inches closed with two motors. I do not know what shop vacs pull in inches, but mine is at least as powerful (if not more than) two LH 220v vacs. I should be in operation tomorrow. Sealed the plenum tonight and putting the new spoil board in place tomorrow. Will advise how it well it holds various materials over the next week. CFM is also an important.

Well I am definitely no expert in vacuums, but I think they were talking about 8-10Hg which is a different measurement than sealed pressure. I have a vacuum gauge and ill hook it to my shopvac tonight and see what it gets.

I am currently running my table off of this old shopvac and I can hold down large sheets of MDF with no issue, was hoping to upgrade to a pair of LH motors and see a significant upgrade so that I can cut smaller pieces without them moving.

here are some pics of my new plenum that I cut last weekend.

24177241782417924180

[barrowj]

I have two LH 220 vacs in a modified black box (I built it for 2 motors) and am getting 8hg with both on. I haven't sealed my bleeder board down yet but on one zone (2' x 2') I threw on a piece of 1/2" mdf just big enough to cover the zone and I couldn't move a 12"28" piece of hickory. Hope that helps, I plan on trying to put down a full sheet of 3/4" mdf this weekend and will know more then. I really hope I did everything correctly and it works :cool: but it looks like it will. I will update this thread when I have completed it.

Joe

[allen00se]

I do not have my vac gauge yet, but others using the same black box configuration have reported 8 inches with the recommended vent hole open and up to 10 inches closed with two motors. I do not know what shop vacs pull in inches, but mine is at least as powerful (if not more than) two LH 220v vacs. I should be in operation tomorrow. Sealed the plenum tonight and putting the new spoil board in place tomorrow. Will advise how it well it holds various materials over the next week. CFM is also an important.

I checked my shopvac over the weekend and it pulled 4hg when completely sealed, its just a 4hp standard shopvac.
24241

[David Iannone]

Allen,
Thank you, that is what I like to see on the forum. Some experiments and the outcome. I am totally new to vac hold down. When I first got my plenum and spoilboard and piping complete I hooked my shopvac to the manifold and was pulling 3hg with the zone totally covered. However, the edges of the zone was not sealed, and PVC was not glued. So your test tells ME that I was losing 1hg somewhere in the edges of spoilboard and/or the not yet glued PVC. I have the PVC glued, box done now with filter. Today I plan on hooking up the box (FINALLY) to my manifold and let her rip. Although, still have not sealed edges of spoilboard but it is interesting to see first hand the results of how much leakage can come from different parts of the puzzle.

Thanks for sharing the pic and description.

Dave

[allen00se]

Allen,
Thank you, that is what I like to see on the forum. Some experiments and the outcome. I am totally new to vac hold down. When I first got my plenum and spoilboard and piping complete I hooked my shopvac to the manifold and was pulling 3hg with the zone totally covered. However, the edges of the zone was not sealed, and PVC was not glued. So your test tells ME that I was losing 1hg somewhere in the edges of spoilboard and/or the not yet glued PVC. I have the PVC glued, box done now with filter. Today I plan on hooking up the box (FINALLY) to my manifold and let her rip. Although, still have not sealed edges of spoilboard but it is interesting to see first hand the results of how much leakage can come from different parts of the puzzle.

Thanks for sharing the pic and description.

Dave

No problem, I was kind of shocked that it was that high, considering some people are saying that the LH motors only pull 5hg when sealed. I would expect them to do much more by just looking at the stats listed on the LH website. I guess I will just go ahead and order one and put the gauge on it to see.



So i just went back and reread the first post, looks like a single LH motor will pull 10hg, so that is much better than what I get with my shopvac. I am guessing that as you add additional motors the Hg doesn't really increase, however you do get additional CFM which is what you would want for more coverage.

[allen00se]

I have two LH 220 vacs in a modified black box (I built it for 2 motors) and am getting 8hg with both on. I haven't sealed my bleeder board down yet but on one zone (2' x 2') I threw on a piece of 1/2" mdf just big enough to cover the zone and I couldn't move a 12"28" piece of hickory. Hope that helps, I plan on trying to put down a full sheet of 3/4" mdf this weekend and will know more then. I really hope I did everything correctly and it works :cool: but it looks like it will. I will update this thread when I have completed it.

Joe

You have any pics or designs you would like to share? I will be building a something similar in the next 2 weeks. Do you plan on running both motors all the time or running only both when necessary? I'm trying to decide if I will need some sort of check valve if I only want to run one at a time.

[David Iannone]

Allen,
I plan on sometimes running just one vac when I am using a small zone. BUT, I don't know if you need a check valve or not. I don't know if the second motor not turned on with no check valve will cause a "leak" so to speak. Good question. Someone with more knowledge will chime in I'm sure. In my case, once I learn a little more about this stuff I think I am going to add two more motors to have 4 total. If you have the room to build the 4 motor box, consider that and just seal the other holes for now, then you can always just throw two more motors in. Just my two cents worth.

Dave

[allen00se]

Just ordered a LH motor, gonna do some testing when it comes in and compare to my shopvac. Will post any results I find.

[kenkelsey]

Just ordered a LH motor, gonna do some testing when it comes in and compare to my shopvac. Will post any results I find.

I just fired up my 2 LH motor box this weekend. With one vac motor I get little to no vac at the table. I believe that one vac motor may suck through the other and not give any vac at the table.

With both LH motors running I get good hold down. I did cut out cabinet parts from a full sheet of 3/4 plywood and the hold was solid even with completely cut-through cabinet profile cuts.

I have a vac gauge coming today sometime and I will advise the Hg I get with both motors running. Whatever it is, its working well for me. From other posts, I am expecting 8 to 10 inches Hg with 2 motors running.

[Gary Campbell]

A few notes from the sidelines:
This thread was started with the best of intentions. An effort to give information that I had gained back to a community that had helped me greatly. It was my intent to post information about a vacuum system that had served myself and a number of others well, so that it could be refined and improved upon and possibly bring users that would not ordinarily be able to afford an "off the shelf" system into the world of vacuum hold down for an affordable amount. An effort to increase their production so that they might afford a "real system".

As I have watched this thread progress, reading most of the 175+ posts over 4 1/2 years I find it somewhat disheartening to have started it. Hundreds of posts that include misinformation, attempts to commercialize the product, and seemingly endless Facebook type attaboys with no value have made the real information nearly impossible to find and sort out.

Going forward, just in case someone wants to do their homework and do a good job with this design, here are some things you may want to know:
This product was sold commercially and when a better design was in the works, the old design, in generic form (pictures, not CAD drawings) was posted to start this thread for this (ShopBot) community

I have not, and will not take credit or approve information from any posts that I have not made. This includes information, drawings or provided files of any kind.

The original design was made from Melamine. Read as stable and non porous. There was no information stating that any type of plywood or MDF would be suitable, and in my opinion are not. All vacuum chamber joints must be sealed thoroughly. This includes plumbing and plenum connections also. Vacuum is air pressure... if you don't seal it, IT LEAKS!

I didn't assume all would use an expensive digital vacuum gauge like I did, but use your heads, its like gas in the car, without the gauge how do you know what you have?

Those that "have used their own ideas" have burned up dozens of motors. Apparently no figured out that with a little adjustment the vacuum exhaust actually created a venturi effect and aided motor cooling.

The Lighthouse motors have a minimum flow requirement to cool the motors. I use a preset check valve that ensures this. A 1/4" hole per motor will also work for the frugal.

I have posted nowhere that a 2 motor setup will be adequate for a 4 by 8 table.

Since I have a financial stake in the commercial products known as the Hurricane, Cyclone and Storm vacuums currently being produced by Black Box Vacuum Solutions, Inc. I will, by agreement, not contribute further to this thread. Neither will I respond to email or PM questions concerning it or variations of it. Sales are approaching a couple hundred units, as the new design, with integrated relief valves, thermal overload and onboard fan cooling has been received very well.


I would also request that my name not be associated with any other individuals design. I have seen nothing posted here in the last year or more that even vaguely resembles the design that I had posted. Sorry for the rant, and good luck with your projects.
Gary