Black Box Vac Source

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.

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

Gary,

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

Great job.

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.

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.

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

-B

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.

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

Gary,

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

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

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

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PICS -

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http://www.talkshopbot.com/forum/pic...&pictureid=124

http://www.talkshopbot.com/forum/pic...&pictureid=123

http://www.talkshopbot.com/forum/pic...&pictureid=122

More pics...

http://www.talkshopbot.com/forum/pic...&pictureid=121

http://www.talkshopbot.com/forum/pic...&pictureid=120

http://www.talkshopbot.com/forum/pic...&pictureid=118

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

-B

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.

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.

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.

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

John

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?

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

No pictures that I can see

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

Gerald

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/y...dmeister/1.jpg

Valve Open
http://i772.photobucket.com/albums/y...dmeister/2.jpg

Valve Closed
http://i772.photobucket.com/albums/y...dmeister/3.jpg

http://i772.photobucket.com/albums/y...dmeister/4.jpg

http://i772.photobucket.com/albums/y...dmeister/5.jpg

http://i772.photobucket.com/albums/y...dmeister/6.jpg

Sorry...but you'll have to refer back to 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

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

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.

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

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.

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

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!

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

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"

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

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

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

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.

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

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

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.

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

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...cuum-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.