PDA

View Full Version : Open Source Vacuum - cont.



ljdm
01-05-2008, 10:20 AM
The specs look very good compared to the Feins. What kind of noise level difference is there? Also, what is the amp draw on the motor? Not starting amps, running. Trying to figure which way to go - 2 Feins, easy setup, low noise, less heat?, lower amp draw?, vs better specs, more work setup, lower cost, etc...........
Thanks for any info

ljdm
01-05-2008, 10:43 AM
Another thought - anybody know if one or two Feins together has enough vac to lift sheet goods, with a couple of pods?

scottcox
01-05-2008, 10:59 AM
Lou,

Frank Leinbach does this with a Gast vacuum pump. I would imagine that the Feins have enough power to do this.

See this thread for his setup..... (Scroll down)

http://www.talkshopbot.com/forum/messages/312/16412.html

scottcox
01-05-2008, 11:02 AM
And another bit of info for this thread. I recently spoke to an engineer at Imperial and he said that the high temp issue could be avoided (or at least helped) by installing a vacuum relief valve just above the first motor (of two in series).

fleinbach
01-05-2008, 11:49 AM
Lou,

Here is a more detailed thread pertaining to information regarding a vacuum sheet lift. I did not test my fein vacuums but I did test my 7.5 pump from Shopbot and it worked but it draws 14 inches of mercury. Since the Feins only draw 6" they would not be able to lift much weight unless you increased the 12" puck size considerably.

http://www.talkshopbot.com/forum/show.cgi?tpc=27&post=44549#POST44549

ljdm
01-05-2008, 12:02 PM
I'll probably just get a separate pump for the hoisting. Thanks for the info. Although after reading the posts, wondering if just a clamp made for sheet goods (similar to those used in lifting sheet metal) might be better, especially for MDF. Will have to experiment and see.

harold_weber
01-05-2008, 06:13 PM
Scott, did the Imperial engineer happen to mention a discharge temperature limit for the blower?

scottcox
01-05-2008, 08:41 PM
Harold,

He stressed that it's not so much a set temperature, but a condition of no air flow as being the killer. The impeller? spins "too" freely, creating heat very quickly thus deformation which destroys the housing.

He said a simple ball and spring type relief valve could be placed in the intake (or plenum) port and set to release just before maximum attainable vacuum (15").

In reality, this would be a safeguard from zero air flow, but from what I read, unless your plenum, spoilboard, seals, etc. are "perfect", there's always going to be residual air flow, correct?

I haven't had much time to pursue this, so I haven't sourced any of the relief valves yet. I think when the time is right, this is the route that I will take.

-Scott

Brady Watson
01-05-2008, 09:04 PM
At the risk of sounding too practical - keep in mind that a souped up Cavalier isn't going to be a Corvette. If you want 'super duty' you need hardware from the beginning designed for that - and that gets pricey as we all know. So, that being said, if you burn out one motor per year, even 2 per year - So what? It's still cheaper than laying out thousands for a large pump. There are trade-offs to everything. I would imagine if you had the time and inclination to do so, you could make a heat exchanger or water jacket and liquid cool it...it's still going to be a Cavalier at the end. Use this type of setup to be able to take advantage of vacuum technology while keeping the investment down until you start making money. When you make some money, buy a professional setup. That's the whole idea here, I've tried to get across since I started this project.

-B

eric_schumacher
01-06-2008, 12:12 AM
Here is a novel idea...

How about using a venturi vacuum, but instead of using one that is powered by an air compressor use one powered by water/liquid.

Something like this:

http://www.plumbingworld.com/minisuctionpump.html

Then instead of wasting water by running this off the garden hose create a closed loop system using a hot tub or spa motor and some barrels. You could even use propylene glycol or something similar as a liquid to reduce evaporation and humidity.

It's just a suggestion as an alternative. Not sure if this specific product can pull enough volume.

On advantage to using this method for other uses is that any evil fumes etc will be tamed by the water. This might be useful when using glues or vacuum removal of bubbles in two part mold making etcs.


I would think there would be an advantage to keeping most of the vacuum lines a small diameter. I see a lot of large PVC and have to wonder if that is efficient. I wonder if putting check valves on smaller diameter pipe as close as possible to the plenum would help with lesser expensive vac solutions.

Using a vacuum storage tank and a vacuum switch that could be used to either switch a vac unit on and off or to switch a valve that could switch between pulling from the system or atmosphere could help with weak pumps or pumps that would overheat when pulling max vacuum.

Brady Watson
01-06-2008, 02:25 PM
Eric,
Test it and report back to the group. At 1st glance, it doesn't seem a good fit for holding things down on a CNC due to lack of CFM, but without test data, one may never know.

-B

eric_schumacher
01-06-2008, 02:47 PM
What sort of CFM is actually flowing at max vacuum with a part on the table? Do you have any data? With a smooth airtight part there wouldn't be any flow..on there shouldn't be. If you were using a vacuum storge unit with check valves how quickly do you lose vacuum on the part side nomrally if the pumps/motors were shut off?

I suppose if your vac design allows for sections of the plenum to be open to the athosphere then you need as much CFM as possible to overcome the massive "leaks".

Anyone reverse their vac system to allow for easy loading of sheet goods? With air pressure the sheet would float enough to slide around.

Gary Campbell
01-06-2008, 03:11 PM
Eric..
Most of the leak we experience is created when cutting thru materials. We have gauges installed on the zones and you can watch the vacuum reduce as the final (cut thru) pass is completed. There are many posts on masks, packing the cuts with sawdust, etc. to help with this problem. Even with 24" by 30" pieces a few prior cuts in the spoilboard will reduce vacuum on the part from 6-7" Hg. to 3 or 4. BTW we are laying on a mask over the unused portion of the zones.
Gary

eric_schumacher
01-06-2008, 03:40 PM
Gary, makes sense. I would envision organizing the vacuum area relative to the parts being cut so that no cut paths had vacuum running through them. Easy solutions for this would be grid channels with (larger than the channel) holes cut for foam/rubber plugs. Use the foam plugs to route the vacuum so it's only under the parts. This solution would work well since you could install new plugs in new cut paths by drilling new plug holes.

Plugs could even mask a cut line in a channel. Just cut through the plug.

I haven't read the other threads so not sure if this is just restating the obvious or not.

Brady Watson
01-06-2008, 03:51 PM
Eric,
Rather than reinvent the wheel, check out the BradyVac II in the 'Brady's Tips/Tricks' section off of the main SB site. I discuss exactly what you are talking about. There are 2 types of systems - one that is universal that requires a load of CFM for cutting most things and the other uses masks, or only areas where the cutter won't get to.

On a CNC cutting most materials, you need a lot of airflow. 1st you need airflow to ensure that you can seal the material to the plenum (get over the hump) before you can start building vacuum. Then, you need CFM to maintain vac pressure if you cut thru the material exposing the vacuum to open air - which for all practical reasons, is gonna happen for most people. If you cut out the same part day in and day out, then the expense and time of making a dedicated jig with no leakage makes sense.

Airflow in a vacuum system is inversely proportional to vacuum pressure. That is to say, if using one of the motors in this thread, vacuum pressure in open air is zero, and CFM is 100 or so. At 9" Hg vacuum pressure, CFM is near zero. When you break thru the vacuum & vac pressure drops, CFM increases.

-B

eric_schumacher
01-06-2008, 04:25 PM
I took a look at the article. I didn't see where you were using channels and plugs. Maybe you meant a different wheel ;)

A little spray of something like Plasti Dip might help with making the seal to the parts. Might be faster than using cut to fit gasketing. Maybe spray it along the channels to both seal the inside channel and coat the deck for a seal.

http://www.plastidip.com/home_solutions/Plasti_Dip

If there is another thread i should be discussing this in let me know.

Gary Campbell
01-06-2008, 05:31 PM
Eric..
What you WANT is a 15hp+ 3ph regen blower. Thats what we all want. What you will read about here is ideas being batted around about trying to mimic the performance of the regen for specific tasks on a much smaller budget. I thought our system worked OK til I saw a 15hp regen at work at John Roughton's shop in Kitty Hawk a couple weeks ago. Even those who have them (like Brady) help the ones who dont with their ingenuity and experience. There are hundreds of posts about vac hold down for both generic and specific use. Our system doesnt use plugs, but we can install AllStar 3/8" round gasket in the channels to limit the area.
Gary

314

eric_schumacher
01-06-2008, 06:24 PM
Cool, Gary. What I thought I was discussing is solving the issue of making a cheap setup. With better control of the leaks etc you can use less vacuum or CFM...but I'll stop now. Just hit the issue with the big guns and get a 15hp blower and forget about it

Gary Campbell
01-06-2008, 06:44 PM
Eric...
Now you have it. IF you have 25+"Hg. and 200cfm, you dont care about leaks. But all the rest of us keep trying different masks, gaskets, zones, pucks,pumps etc. etc. to try to do the job at hand on the budget we have. As Brady says above.... do your testing, and Please! report back to the group.
Gary

john_l
01-09-2008, 03:05 PM
I have made plywood boxes to house the vac motors just like Brady's. I made a round hole for the black plastic, vented motor end to stick out also... do you guys think there any need for additional ventillation across the "motor" side of the vac box? I feel air drawn into the motor end from the outside but where is that air going? Out the exhaust?

Someone had asked about amp draw. Mine is drawing 13.1 each when sealed off tight. I have 2 motors so I ran 2 20 amp circuits.

Mine is working great so far. I'll get a vac gauge and also post some pics soon. Thanks.

... and Thank You Brady. I never would have had a clue how to do this without your starter posts here.

3imoh
01-13-2008, 01:32 PM
It is great to see folks making progress with these. Thanks to Brady to getting the ball rolling!

Does anyone have a sense of the max air temp the 2nd motor would see if run in series for a long time? I am looking at 3 way valves...brass is prohibitively expensive, but the CPVC version of the pool valve mentioned above looks like it might work. CPVC handles a max temperature of around 180 to 200F.

I am seriously considering getting 4 of these motors...just debating if I want to mess with being able to switch them from series to parallel. Seems like having each set of two permanently configured in series would be a pretty good setup...15hg and ~200cfm (on paper). Although having close to 400cfm available would be nice as well...

-howie

Brady Watson
01-14-2008, 09:54 AM
Howie,
If you ran these in parallel, I think that you would be pretty happy with the results. If you can pull around 9" Hg and you have 400 CFM, that's a nice combo. It's about 2" Hg more than a Fein, and well...you know how much cheaper it is.

-B

john_l
01-14-2008, 11:41 AM
Here's some cell phone pics of mine.
315

john_l
01-14-2008, 11:42 AM
another...
317

john_l
01-14-2008, 11:42 AM
another...


318

john_l
01-14-2008, 11:43 AM
last one...


316

paco
01-14-2008, 12:34 PM
Nice built John!

Any chance we can see the inside of the motor/filter box?

Brady Watson
01-14-2008, 01:24 PM
Looks great, John! Thanks for posting pics to the group!

-B

ed_lang
01-16-2008, 03:39 PM
Just got my two motors to test out and I am impressed. The noise is less than I expected but still a lot more than the Feins I currently use. I did get two mufflers to try. With one motor laying on the bench and making maximum noise I just sat one of the mufflers over the port and the noise almost went away all together. You can hear the blowing of a lot of air, but not the high pitch scream that drives me crazy. Impressive. I will be making my mounting system in the next day or two and trying out different things with them. I am not going to run in series at least not now. My Feins measured 6"Hg today and the new motor measured 10"Hg. The gauge was bouncing around so I expect it really was the 9 to 9.5"Hg that the spec call for. Putting the second muffler in series with the first didn't decrease the noise that I could tell. It is just plain old quite.

The amount of heat generated is a lot more then I expected!

br928
01-16-2008, 04:27 PM
Ed,

I got two of the motors too. Which mufflers did you get? I was thinking of building my own muffler similar to the design for cyclone dust collectors but smaller. If it is a good price and works well maybe it is not worth my time to build my own.

ed_lang
01-16-2008, 05:07 PM
I got Ward to send me two with the motors to test out.

Send Ward an email or call him. I don't have the invoice at hand to tell you the price of them. They are available two ways... One with the clamps and flex coupling, the other way without all of that. I would buy them without, now that I see what you get.

pfulghum
01-16-2008, 06:13 PM
Ed,
What did you do to address the sound (which muffler)?

-- pat

john_l
01-16-2008, 08:10 PM
Ed, I am interested in your mufflers also. These things make a racket over here.

Paco, Here's some inside pics. I am just a copy cat, looking over Brady's shoulder. In use, I have noticed that I am not getting any dust hardly in the filter section so I guess the trupan bleeder is working for me. I am getting just a little dust inside the motor area. I think the little fan inside the black end housing is drawing it in. I guess under the table edge isnt a great spot to locate these pods
.. the way I have it, they are easy enough to relocate if need be, I just wanted to limit the length of pipe as much as possible.

I left room to expand into 2 more vacs later but I can't see the need in my case. It holds full sheets and small pieces.. I just cut up a sheet of plex into 7" x 12" rectangles with 1/4" router kerfs all around them.. never taped or even tried to limit the leaks.. every piece held tight. I just directed both vacs to one of my 1/4 table zones (2x4') and layed a 12x36 piece of mdf on there... I couldnt budge it with all my strength to any side. This thing really works.


319

john_l
01-16-2008, 08:12 PM
Another view


320

john_l
01-16-2008, 08:21 PM
One other thing I wanted to mention... I have noticed a couple posts here regarding the heat generated by these motors? I never tried the series operation, but using them in my setup, even the exhaust isn't really even hot. Granted it's wintertime here and a little chilly in the shop now but the other day we had 73 degrees and I kept checking the exhaust temp by hand... never heated up. Do you think maybe I am moving more air (cfm) through the bleeder and therefore keeping it cooler? Maybe the shopvac filters have less restriction?

paco
01-16-2008, 08:23 PM
Thanks for taking the time to take and post the pictures.

I'm considering something like that as well. One addition I have already though of is a baffle/filter for the motor fan. Another idea was to use the vacuum exhaust velocity to extract the motor warm ambient air... does the motor get any (too) hot after running for some time in the enclosure?

john_l
01-16-2008, 08:35 PM
When I took these pics this evening, I had just shut down from running them for about 1-1/2 hours cutting some aluminum sheet up. So the aluminum is about as non pourous as anything I have put on there, I'd expect the heat to build up. I don't have an accurate way to tell the exact temp. But by touch, they just felt maybe a little warmer than a normal appliance motor that had ran the same amount of time (to me). I have not sealed the edges of my bleeder yet. I actually got lazy on that cause it has been working for me... and I am now working on this theory that maybe a little leakage is a good thing as far as keeping things running cooler (?).

Brady Watson
01-16-2008, 11:16 PM
See attached ZIP with files for making your own VacBox (for the eternally lazy) - I just stumbled upon the files and figured it does me no good to just have them laying around...and besides, maybe a few more of you who have purchased the motors (but haven't done anything with them yet - slackers you know who you are!) - would be inclined to get moving on the project and post up their system, findings and details to inspire others.

Be sure to view the ReadMe attached...and if you make one of these boxes, don't keep it hidden...show it off!

-B

VacBox.zip (http://www.talkshopbot.com/forum/messages/28/VacBox-26993.zip) (5.2 k)

ed_lang
01-20-2008, 11:57 AM
My Feb article for ShopBot will detail the housing I built and the use of the mufflers. Not trying to keep you in waiting for that article I'll post a couple of pictures here so you can see what I did to create a quite two motor vacuum source that can be expanded to a 4 motor unit real easy. I do not have a sound meter so I cannot say how loud this combo is but I am able to talk in a normal voice standing right next to the vacuum unit. It is not any louder than the two Feins I have been using thats for sure.

This is my testing configuration. I plan to wire them up a different way for the final version. I also plan to make a filter box that will connect into the system. More about that later.


321

You see one muffler on the left motor here. The motor on the right get a muffler too. I can also vent the mufflers outside in the summer time to keep the heat out of the shop. This time of year I want all the heat I can get in here!


322

br928
01-21-2008, 02:46 PM
I am curious is any additional noise reduction can be accomplished by isolating the blowers from the enclosure. Seems like the rigid attachment to the enclosure would act like a sound board to amplify any vibrations.

Brady Watson
01-21-2008, 04:00 PM
Stan,
The noise you hear is more attributed to 'induction noise' than vibrations from the box. In fact, my friction-fit box didn't really vibrate at all sitting on the WorkMate.

The idea is to slow down and interrupt the airflow a little to break up some of the noise caused by velocity. This is how the muffler on your car works. There is also some sound reduction to be gained on the intake side if it is a completely open system, like your car - most cars these days have an intake silencer that is often attached to the inside fender of the car. Remove it to pick up some air flow...and add some more 'Ba-wah' when you put your foot down ;)

Here's what a regular old 'turbo muffler' looks like when cut away:


323

and here is a pic of one of my experiements with convoluted foam...be aware that I have not tested it for fire/heat resistance! The convoluted foam would actually work really well on the cooling fan side of the motor, as long as you were sure that the motor was getting enough air past it to keep the motor cool...which means adding a chamber to the box for the cooling fan intake air to snake thru like a labyrinth.


324

-B

bcammack
01-22-2008, 08:22 AM
Brady, here's some acoustic foam products that _are_ fire safe.

http://www.markertek.com/ProdList.asp?cat=ACOUSTICS&subcat=&prodClass=ACFOA M&search=0&off=

preimp
01-22-2008, 08:57 PM
Hi all. So I just finished the 9-15 Vac project and it works amazingly well. The big thing that really helped my setup was masking the edges of the bleeder to the plenum. Anyways, I wanted to send a big thanks out to Brady for coming up with this. It's pretty neat, especially coming from my perspective having never used vacuum before. I think I need a better gasket on my filter box though..It looks like its oozing out!! OOPS!!
Thanks for all of the input on this forum...It's amazing!!! Hopefully I can contribute.
325

Brady Watson
01-23-2008, 12:39 PM
Looks like a pretty straight forward setup, Chris. Nice work. Thanks for posting pics!

-B

paco
01-27-2008, 08:42 PM
This (http://www.youtube.com/watch?v=p3HVmM73-7M) is the filter/motor box I think it'll be for me.


326

I had to provide an area for chip and dust accumulation since I don't have a bleeder board. Everything (motor cooling filter element, motor, filter element) will be reachable from the top.

ed_lang
01-27-2008, 09:33 PM
I like the closed look of all these box designs. But I fear the motors will get too hot with extended runs. I have not see any vent holes to allow the cold air in and the hot air out.

I will stick to my open design and see how the closed boxes work out in the long run.

Forum Admin
01-28-2008, 01:47 PM
Separated this topic into two threads and had to remove some posts that were stretching window.

br928
01-28-2008, 03:44 PM
Paco, Might as well put a large shop-vac bag in the first compartment to keep from loading up the filter.

Ed, Paco's design has a baffle to reduce the motor fan noise. The motor fan is pulling outside air to cool the motor. Assuming the motor compartment is not air tight, this air exchange should be more than enough to keep it cool. (and much quieter)

Paco, You might put a frame around the end of the box to hold a standard HVAC filter. That would keep any dust out of the motor area that someone spoke of earlier.

br928
01-30-2008, 02:19 PM
In keeping with Brady’s original post to make a vacuum system with two motors connected in either parallel or series, to obtain higher CFM or higher vacuum, and inspired by Paco’s success in using a sliding gate valve in vacuum service here is a design that will simplify the operation and further reduce the cost.

There had to be a way to simplify the plumbing and get rid of the troublesome (and relatively costly) ball valves. Someone in an earlier post mentioned a 3 way pool filter valve. A simple one turn solution to series or parallel the motors but expensive. The answer is a 3 way sliding gate valve. Made from material (MDF) everyone has laying around the shop and this can be made at little or no cost.

The slide valve consists of three ports. In position 1 (parallel) the top and bottom ports are open and the middle is closed. The top port connects the exhaust from the first blower to its muffler. The bottom port connects the second blower’s inlet to a common suction header. The blowers are running in parallel mode.


327

By moving the slide to position 2 (series) the top and bottom ports are closed and the middle is open. The top port blocks the outlet of the first blower to its muffler. The bottom port isolates the inlet of the second blower from the suction header. The middle port connects the outlet from the first blower to the inlet of the second. The blowers are running in series. Simple enough?


328


329

This prototype is made from ¾” (body) and ¼” (slide) MDF. The body has three holes on each side 5” on center. A piece of 1-1/2” PVC pipe was cut and inserted in each hole till it was flush with the other side and held with superglue. The inside was sanded till the pipe was flush with the inside surface. All interior surfaces of the slide were sealed with sanding sealer to make them non-porous then waxed for lubricant. 1-1/2” holes were cut in the slide in the appropriate places and a slot to limit the slide travel.


330

Doing it again I would not have used the cast floor flanges for the blower adapters. I would have used the pipe, like the valve, and saved another $10-$15.

The next step is to build an enclosure to house and quiet the beast.

Brady Watson
01-30-2008, 02:47 PM
Hey Stan,
That looks like a really great idea! Thanks for sharing. Let us know when you get it running and take it thru the paces.

-B

ed_lang
01-30-2008, 05:37 PM
Stan!

Bravo!

ward
01-30-2008, 06:23 PM
And the motors have plenty of air for cooling! Very creative!

br928
01-30-2008, 07:44 PM
Ward, This whole assembly will eventually find its way inside an enclosure. I think if the cooling fans on the motors are allowed to pull in filtered outside air, the resulting positive pressure will force the warm air out of the vented enclosure. With enough air exchanges motor heating should not be an issue even with extended use.

I also has two of your mufflers (not pictured, they showed up 10 minutes after I posted) to add to the system.

To try to further reduce the noise level the blower/motors will not be directly attached to the enclosure but supported by the PVC plumbing within the enclosure. This should further isolate the noise source from the outside world.

john_l
02-01-2008, 07:58 PM
I just added a vac gauge to my system earlier today. I added it in the main 2" PVC Y pipe that ties my 2 vac pods together (see my setup pictures above).

It measures about 10hg with one vac running, all valves closed.

About 12hg with 2 vacs, all valves closed.

About 4-5hg with nothing laying on the trupan bleeder (edges still not sealed), 2 vacs, all valves open.

About 10hg with a full 4x8 sheet of acrylic laying on the bleeder, no cuts, 2 vacs, all valves open.

After cutting the entire sheet of acrylic up into 12" X 12" nested triangle shapes that also had several mounting holes (w/ a 1/4" 0 spiral) the vac gauge dropped to about 8hg.

Does all this sound about right?

As with all my experience with this setup so far.. All parts held tight throughout the part runs. I still throw on a perimeter clamp occasionally just out of habit but I really don't need to at all.

gskinner
02-02-2008, 08:45 AM
Ed,
I like your design for the vacs. Could you tell me what size your boxes are and what size holes you cut for the motors? What model motors are you using?
I don't have the motors yet but would like to get the box made up in advance.
When will your article be posted?

Thanks

ed_lang
02-02-2008, 11:26 AM
Hi George,

I am working on getting the article finished this weekend. Jobs in the shop have kept me from finishing it up. Just as soon as I finish it, I will post for ShopBot. They are quick to get it on their site.

gskinner
02-02-2008, 02:03 PM
Thanks Ed,

I was hoping to get started today or tomorrow on the box. If you could tell me the size of holes to cut for the vacs and width of top so I allow enough room to mount them I would appreciate it.

Thanks

geneb
02-14-2008, 02:10 PM
Here are a few pics of my "one lung" version:

http://www.simpits.org/~geneb/bucket_topper1.jpg
http://www.simpits.org/~geneb/bucket_topper2.jpg
http://www.simpits.org/~geneb/bucket_topper3.jpg

It's designed to sit atop a 5 gallon paint bucket. Or at least that was the original idea. Little did I know that dinky little motor would turn into a miniature black hole and promptly cave the side of the bucket in.


Even a bucket-in-a-bucket didn't survive.

The motor has gasket material attached around the input port and it seals nicely against the plywood. I've got a newer version that uses 2 motors atop a small steel drum. I'll post pictures of that as soon as I can.

Those motors are insanely loud. It's no fun to be around them even with hearing protection on (the muffs, not the tiny plugs)

Admin: please increase the picture size limit in the forum. It's completely inadequate.

g.

Brady Watson
02-14-2008, 03:01 PM
Gene,
The 'DrumVac' concept was the idea from the start, as an easy way to mount everything up. You can see an example using a 15 gal drum here (http://www.talkshopbot.com/forum/messages/28/22456.html?1201487608)

The only problem was that the drum with motor on top was taller than underneath the Bot, which meant that I had to lay it on it's side on a cradle of sorts.

-B

geneb
02-17-2008, 03:31 PM
I've got enough room that having a tall vac isn't much of a problem.

I do wonder if I can stuff this thing outside with my regular dust collector. The 2" pipe run would be about 60 feet. Can you see a problem with that? Beyond the huge potential for leaks anyway.


Two of those motors running at the same time is loud enough that I'd rather stand outside in the rain than have to be dry and listen to them.


g.

Brady Watson
02-17-2008, 04:22 PM
You can put the vac powerplant outside, but realize that you are going to have losses in airflow. Every extra length of tubing creates friction as the air passes by it & slows it down. Every elbow, bend or transition also slows it down. Keep bends to a minimum & to reduce wall friction, you can use the next size up tubing/pipe. Aside from this, you should not have any reduction in suction, but performance will fall off a little sooner since you won't have as much CFM to overcome leakage if you do cut thru your parts an expose the vac to open air.

-B

br928
02-17-2008, 06:54 PM
I don't think the end result will be as quiet as my Fein (what is?) but it should be reasonably quiet. I built the enclosure to house my 9-15 slide valve system this weekend. It measures 44" x 21" x 11". Its footprint is small enough to mount under the Shopbot table. I also used an automotive air filter (Suburban $15-$25) and easy to get at any parts house. I have yet to duct the motor cooling fans to the outside of the enclosure. I bought some 3" flexible aluminum duct and with a large clamp it fits right over the top of the housing.



331

Brady Watson
02-17-2008, 08:10 PM
Looks great, Stan. Let us know how well it works for you. Great job on the slide configuration.

-B

larry_r
02-17-2008, 08:15 PM
Stan

That is a very nice design.
Thanks for posting the pic.

Larry

ed_lang
02-17-2008, 09:09 PM
Stan,

Best design I have seen so far!

Everyone seems to think about getting the top of the motor fan to some source of cool air, but I don't see the exit hole for the hot air! If the air cannot get out, fresh air will not get in.

geneb
02-17-2008, 09:23 PM
Here's my two-motor design:

http://www.simpits.org/~public_html/2lung_vac1.jpg (http://www.simpits.org/~geneb/2lung_vac1.jpg)

Brady, would 4" pipe be a better choice then?

g.

geneb
02-17-2008, 09:25 PM
Ok, message editing doesn't work.

The correct URL is:

http://www.simpits.org/~geneb/2lung_vac1.jpg

g.

br928
02-17-2008, 10:07 PM
Ed, As far as venting the enclosure, there is a 1/4" gap around the muffler from the #1 blower where it exits the right side. If this turns out to be too restrictive, then I will add aditional vents. I am trying to keep as much noise inside as possible with as few penetrations as possible.

My blowers are drawing about 10 Amps of power each. To those who are powering two blowers from the same circuit, just be sure it can provide 20 Amps continously without overheating (wiring), especially if running the vacuums for long periods of time.

ward
02-18-2008, 04:17 PM
Again - VERY creative. If the mufflers were pointing in the same direction it might run all around your shop! Jet Propelled!

br928
02-18-2008, 05:37 PM
Ward, I am getting too old to chase it. This way it just spins in place like a pinwheel!

ward
02-18-2008, 07:42 PM
Stan, you might try one of the white mufflers on this page on the inside of your box to deaden the noise from the motors and cooling fans. They are 5.5" in diameter and 5.1" tall. They are designed for central vac's to keep the noise from going into the house. The sides are straight. It does not get smaller from one end to the other!

http://www.lighthouseenterprises.us/muffler.htm

Then you could make any size vent hole that you like.

bernott
02-18-2008, 08:21 PM
What are these vacs? sorry to sound stupid but I can't find anything that looks like these pics.

bernott
02-18-2008, 09:04 PM
Sorry if I learn to read I'd find out!

ward
02-18-2008, 09:04 PM
Go to: http://www.lighthouseenterprises.us/imperial.htm

VBTST6460VM

br928
02-19-2008, 11:26 AM
Ward, It looks like these white mufflers cover the motor portion of the assembly. That may restrict the airflow around the motor somewhat. Under normal usage that may be fine. However, in this application where these vacuums may operate in a near dead headed condition, for long periods of time and with little airflow through the blowers, the operating temperature of the housing and motors rises significantly (HOT). I would be hesitant to put anything even close to these. If fact some cooling fins of some type around the main housing might be in order(Anyone have any ideas here?). In open air the blowers are drawing about 13 Amps and deadheaded it drops to about 9 Amps. That's 1500 to 1000 Watts that must be dissipated. With full air flow that's not a problem. With no air flow things get hot. Try plugging the suction side of your hair dryer for a little while and see what happens. Like most things, life expectancy is proportional to the temperature of their environment.

ward
02-19-2008, 10:40 PM
Stan, you are correct, very correct. They are designed to go on the inside of the central vac can and go over the port where the house piping comes in. The only way that they would work for you would be to one over each of inlet cooling pipes to the top of the motors on the outside of the box. You might just put some 1/4" to 1/2" foam like in the mufflers inside your piping to the top of the motors?

br928
02-25-2008, 07:38 PM
Update of this weekends progress on the slide valve 9-15. I ducted the cooling fans to the outside of the enclosure w 3" aluminum duct. I also added an additional exhaust vent with some of the remaining aluminum duct. (Had to find something to do with it!) Ed can rest now knowing the the hot air can now get out. The intakes are still quite noisy and will have to put some type of baffle / filter over them.

I had to add a removable brace across the filter box. Enough vacuum is generated to flex the sides and make the gasketing walk out from under the lid. I may still have to add another brace in the front section for the same reason.



332

Test runs confirm that this configuration will produce 9" and 15" Hg. With just one blower running in series mode a little less that 9" was achieved.


333


With the slide valve the configuration can be quickly changed while the system is running to suit your needs.



334

paco
02-25-2008, 08:04 PM
Nice work Stan! Does your slide valve leak some?

I must have a defective vacuum gauge since I only reach 7"Hg with a well sealed mock up directly on the motor/vacuum unit...?! Both units tested.

Brady Watson
02-25-2008, 08:25 PM
Bravo Stan!

So is that thing going in a museum or are you going to actually use it?
It looks like it turned out really well & that you put a LOT of time, effort & care into it's execution. Thanks for posting pics!

-B

br928
02-25-2008, 09:34 PM
Paco, I can't detect any signs of leakage. It was pretty easy to hold some tight tolerances. All the internal surfaces were painted with sanding sealer and then sanded on a flat surface with 320 sandpaper. I used layers of scotch tape as a shim material when assembling to get it where slide just operates without sticking.

Brady, I was just commenting today that is starting to look like a science fair project. Not counting my time (and who does) I still have less than $350 invested. Today's prices will be about $40 more. How much did I pay for my Fein? My vac gauge didn't get to 6" when I tested it.

Brady Watson
02-26-2008, 12:02 AM
I guess it could be both functional and a conversation piece if you put a piece of clear plex on the top of it...

-B

john_l
02-26-2008, 06:57 AM
Stan,

Great job, well done.

br928
02-26-2008, 09:37 AM
Here is some acoustic foam that is flame retardant at a reasonable price.

http://www.partsexpress.com/webpage.cfm?Webpage_ID=3&CAT_ID=34&ObjectGroup_ID= 94

ed_lang
02-26-2008, 11:06 AM
Stan,
Looks great!
When do you take this to market?

Brady Watson
02-26-2008, 11:51 AM
Ahem...Just as a friendly reminder - this is an 'Open Source' project, meaning that it came out of my R&D department & shared with this group for free. I decided not to sell plans, or kits, but share it with you guys for free. The finer points of this project have been developed by this community up to this point...So selling a 9-15 for commercial gain probably wouldn't be a very cool thing to do...Let's keep the open source stuff going. I have a few more things that I'd like to put out as open source, but I won't if people are going to abuse the concept of community and sharing.

-B

br928
02-26-2008, 01:02 PM
I agree with Brady but I think Ed was speaking with tongue in cheek and meant that as a complement. Besides, no one could make any money selling to all you DIYers.

In the spirit of 'Open Source' I have already, and will continue to share my VCP files to anyone wanting to give it a try.

ed_lang
02-26-2008, 06:53 PM
Brady makes a good point and it needed to be said. It keeps the air clear.

Stan hit it! I think what Stan did was take a project and move it up to a "commercial" quality DIY project.

I use Open Office too, I like the spirit of "Open Source"

maginter
02-26-2008, 09:06 PM
Nice Job Stan! So when does Norm Abram come in and say "if you would like to build this, a measured drawing is available"..... :@)

Seriously, if you ever think about selling plans for the design, I would be interested.

Mark

kivimagi
02-26-2008, 11:03 PM
Just an FYI open source stuff is sold for a profit all the time. mySQL linux etc

What is sold is the "service", support, or modifying code to suit other systems, etc.

An interesting note is that Sun Microsystems just bought mySQL for $1 billion.

I certainly don't want people to stop sharing, but what Stan would be providing would be his time, and the commercial quality as Ed was referring to. I'm not really sure it violates open source as a culture.

What would be wrong with Stan assembling these, and selling to others? Its just division of labor, if he even wanted to.

Anyway that is my .02 cents. Which with inflation is now worth nothing.

Regards,

br928
02-26-2008, 11:16 PM
Mark,

In my previous post:

"In the spirit of 'Open Source' I have already, and will continue to share my VCP files to anyone wanting to give it a try."

These are V Carve Pro files. Please email me directly.

BTW- Its not a "measured drawing", its a "measured drawering" (gotta use a yankee accent)

maginter
02-27-2008, 10:53 AM
Thanks Stan! I have made the accent correction... ;@P

br928
03-01-2008, 03:45 PM
Today I put the final touches on the 9-15 slide valve enclosure. I built a baffle/filter box for each motor intake.


335

I also lined the exhaust and inlet ducts with noise absorbing foam.


336

The baffle boxes where then attached to the enclosure. Some filter media was folded and inserted into the bottom of the baffle boxes in an effort to keep some of the dust out of the motors. Although I don't think the dust would hurt anything this extra step can't hurt.


337

I was supprised how much air is moved through the enclosure by these motors. I don't think the interior will get that warm. In series mode the housing of the second blower is reaching 160 degF after 5 minutes. I don't know if it will get hotter on longer runs.

All in all it is reasonably quiet. I think more sound material inside my reduce it further but with a DC and Bot running I don't think it matters.

Now I have to find something to do with it huh Brady.

ward
03-01-2008, 10:12 PM
Simply BEAUTIFUL!

carvingartists
03-08-2008, 02:58 AM
Here's a couple of pictures of the vac I have been working on.... With all four running in series it pulls 20" of Hg! With each box in parallel,and the two boxes in series it pulls 15" of Hg and about 200 cfm..


338
Rear view two boxes in series




339
Front view two boxes in series


340
All four motors running in series pulling around 20" of Hg!

Thanks to everyone who posted on the forum about this subject!

I will post more pics and info when finished.

Blair

Brady Watson
03-08-2008, 06:43 AM
Pretty impressive, Blair! Thanks for posting!

-B

Brady Watson
03-30-2008, 05:46 PM
Just for thread/concept continuity of the subject matter for those researching...The QUAD (http://www.talkshopbot.com/forum/messages/28/29326.html?1206913364) by Ed Stutz

-B

weslambe
04-04-2008, 10:54 PM
Stan Holt let me borrow his vacuum pump for some real world use. I hooked it up tonight without taking the time to make sure all of my pvc is sealed and I get about 5-6" hg (running parallel) with a 48x96 sheet sitting on top of my 49x97 spoil board. The 188 CFM and the 5-6 inches is far superior so far to what I am used to seeing.

I will be very pleased if I can cut some smaller parts without them moving.

harold_weber
04-10-2008, 12:17 PM
Shopbot's Gordon Bergfors suggested I post these photos - they might give you some ideas.

I was never comfortable running my Fein vacuum for long periods and so I turned to a regenerative blower which has a Totally Enclosed Fan Cooled (TEFC) drive motor. The first photo shows the parts mounted on a low platform cart I built that fits under the end of the table. You can see TWO filters - the larger one is for air coming from the spoilboards and vacuum fixtures. The smaller one is connected upstream of the vacuum relief valve (the black item in the photo).

Those of you who are wondering why you are seeing a Porter Cable 7518 router mounted in a (red) Jessem router lift at the top right of the photo, I have a 60 by 120 table, and I can remove this portion of the top if needed, install the PC router and lift, and do some additional (non-CNC) machining on parts.


341

Here is a bit of information for you Fein owners; I was NEVER able to get the Fein I have to draw the advertised 99 inches of water vacuum. I know I cannot do this unless the local barometric pressure is 29.92 inches mercury, but the best I could do with the inlet totally blocked on the Fein was 82 inches water. This was the best reading after trying 4 different gages. Now, 82 inches of water is not consistent with the local elevation of 650 feet above sea level. I even went to the local Woodcraft store and persuaded them to my gage on their new-in-the-box Fein - it still read 82 inches water.


342

Look at the first photo and you will see two small gage lines connected before and after the main filter. These lines go to the gages shown in the second photo. The left gage shows I can pull 140 inches of water on one of my spoilboards with a given part fixture installed. This is the advertised max vacuum that the regenerative blower maker stipulates - apparently they are a little more conservative than Fein. Even at 140 inches of water, there is still plenty of cooling air running through the regenerative blower (through the bypass circuit). A back-to-back test substituting the Fein showed the Fein would only pull 50 inches of water on the same setup.

The right hand gage shows that the pressure drop across the main filter is essentially zero (the filter is clean and the flow is low). These are Dwyer Photohelic gages. The black pointer reads the actual vacuum, and the two red pointers are adjustable. When the black pointer aligns with a red pointer, a relay is tripped. By using these gages, I can wire an alarm to trip at any settable pressure drop across the filter. This will remind me that the filter is dirty and its time to clean it.

What's my follow on project? The photo below shows some additional parts I've picked up. When I get a little more time I plan to plumb the two regenerative blowers in series. The radiator will keep the air flowing into the second blower cool - I'm still shopping around for a small radiator fan or two to cool the radiator.

Also shown in the last photo is a ladies' silk stocking stretched over the bypass line filter - an inexpensive disposable pre-filter suggested by Gordon Bergfors.


343

paco
04-10-2008, 01:27 PM
quote:I was NEVER able to get the Fein I have to draw the advertised 99 inches of water vacuum. I know I cannot do this unless the local barometric pressure is 29.92 inches mercuryThat might be my problem too... I do not get the 9 in.Hg I was hoping to reach with the vacuum motors discussed in this thread. Yet I don't know what is the elevation of my city.

What is that blower model #? Is it the kit from ShopBot? How noisy it is? 140 in.H2O is pretty good but what's the air flow?

Thanks for sharing Harold!

OT: Jessem good products? I have an eye on the Master-R-plate for a dedicate router table...

harold_weber
04-10-2008, 02:54 PM
Paco, all the vacuum components you see in those pictures EXCEPT the vacuum relief valve was purchased for around 10% of new cost on EBAY....... The blower in the foreground is Siemens 2BH1410 driven by a 3.4 HP 3phase induction motor. It is a two-stage unit.

I've had the Jessem Master Lift since 2003, and it has worked very well for me. I was worried that the cog belt pulleys that drives the lifting screws would plug with wood shavings, but it seems fine. Its been long enough now that they may have changed the design.

The blower discharge is a little noisy (not as bad as a Shop Vac), but I have piped it to another (unused) storage room so it does not bother anyone.

Paco, I am not familiar with Quebec's governmental web pages, all I can say is that the US Geological Survey has altitude data in the form of contour maps for the US, you will just have to figure out the name of the Quebec agency that has this data.
Not sure where you are relative to the Valcourt airport, but it is listed as being at 740 feet elevation.......

At the risk of confusing everyone, you can figure the effect of local ambient pressure and temperature changes using the following formulae:

Pressure correction:
DeltaP,local = DeltaP,standard day,sealevel *(barometric pressure,local/barometric pressure,standard day,sealevel)

Example, The manufacturer cites that the pump will supply a max delta P of 140 inches water at a standard barometric pressure of 29.92 inches mercury and an inlet temperature of 15 C. Today the local barometer reads 29.17 inches mercury in your town. So,
Delta P = 140 *(29.17/29.92) = 136 inches water

Inlet Temperature correction:

DeltaP, local = DeltaP, standard temperature * (Standard Absolute temperature/Local absolute temperature)

where absolute temperature = degrees C + 273
or local absolute temperature = degrees F +460

So, if today the temperature at the pump inlet is 27 degrees C, then

Delta P = 140 * (273+15)/(273+27) = 134 inches water

Note that the actual pump delta P will depend upon BOTH of these effects (temperature and pressure), so BOTH corrections must be applied:

Delta P = 140* (273+15)/(273+27) * (29.17/29.92) = 131 inches of water

Paco, what is the frequency of alternating current driving the blower? If it is 50Hz and not 60Hz, this will have a much larger effect/ The pressure will depend upon the square of the frequency ratio, so at 50 Hz, the 140 inches of water will become: 140 * (50/60)^2 = 97 inches of water.

Brady Watson
04-10-2008, 04:26 PM
Paco,
The Fein is only rated at 7.3" Hg, not 9.

Just for reference, since most of us on the board speak about vacuum, we use inches of mercury (Hg"), here's the conversion:

Convert inches of water into inches of mercury, divide by 13.6 - multiply by 13.6 going from inches of mercury to inches of water.

E.G. - 7.3" Hg * 13.6 = 99.28" H2O
------ 99.28" H2O / 13.6 = 7.3" Hg

This is an area of confusion for a lot of people, so that's the reason for posting.

I was hoping that this thread would be for the 9-15 vacuum project only. Perhaps you can start a new thread for general vacuum discussion so that this thread stays consistent with the original thread. (http://www.talkshopbot.com/forum/messages/28/22456.html?1201487608)

-B

paco
04-10-2008, 05:56 PM
I was referring to the Imperial motor... you know, the ones I bought...!


Still, I'm happier than with the Fein III since I have motor volume displacement. Yet the problem light be the gage I have.

I should post pictures of my motor/filter box but I was waiting for some parts for the final touch...

harold_weber
04-10-2008, 08:27 PM
Paco, my earlier comment on 50 Hz AC line frequency does not apply to series-wound universal motors. This is what I believe are used in the Imperial and Fein vacuums, so I'm sorry I miss-spoke. A lower frequency is not likely to be the cause of your low vacuum.

Brady, here is your comment last July in the original thread: "Anyone and everyone is welcome to participate, do their own experimentation and share it with the community. Harold, if you are an air-flow engineer of sorts, you should be dispensing this knowledge to the group, showing examples of projects/methods that you have created."

My understanding of the 9-15 project is a two motor system that will out-perform a Fein vacuum and cost less. Is this incorrect? Given that I've bought each of the regenerative blowers for my system off EBay for 100 US dollars or less, and the intercooler for 60 US dollars, my system low-cost. Each of the regenerative blowers I bought out-performs a Fein. So why doesn't it belong in this thread - are we limiting this discussion to those who build their systems using Imperial brand vacuum motors??? Does the suggestion to use a differential pressure gage to monitor filter pressure drop not belong here???

I do need to mention that the regenerative blowers use three-phase power, so there will be an additional expense if you haven't got 3 phase power. You can find plans and components on the internet to build a phase converter.

Brady Watson
04-10-2008, 09:27 PM
Harold,
I am certainly not discounting your contribution(s) - by all means share with the group. Yes, I was kinda hoping to keep THIS particular thread focused on Imperial powered designs, if for nothing more than simplicity to the reader. If you switch brands & start talking in H2O" vs Hg"...readers are liable to get lost. It's pretty easy to start a new thread with a link to this one if need be.

I for one am VERY interested to hear about your successes with the regen setup. I'd love to know how they work in series. I think it's pretty interesting how many innovations have sprung up from this community...It would be fabulous if there was a Vacuum category on the board so that new threads (and related posts) don't get lost in the mix of things. This thread will probably be broken up again since it is getting a bit long to load.

By all means...keep posting!

-B

ed_lang
05-05-2008, 12:04 PM
Here is the second revision to my cheap and easy vacuum system. I did cut the wooden mounting disks on my laser but you could have cut them with a jig saw just as easy.

Vacuum motor, 2" metal flange, wooden disk

344

This is how the assemble goes together. Use silicone or gasket between metal flange and vacuum motor.

345

Continued next post.

ed_lang
05-05-2008, 12:18 PM
This is how the metal flange will fit onto the vacuum motor housing.

346

Complete assembly ready to glue up to the second motor assembly.

347

Two motors mounted and ready to install muffler.

348

This is how I used a 45* and a Tee to connect two exhaust ports to one muffler. I felt this was fine since I don't expect to be moving max air when cutting.

349

Three sided box allows the vacuum motors to just sit on top.

350


This set up is MUCH quieter than the first one I build in the wooden box. I expect it is because I do not have a box to resonate. Notice I am putting foam insulation under the stand here to isolate the motors from the concrete floor. I also installed a 2" flexible connection between the valves and the vacuum motors. This will stop vibrations from traveling up to the valves as well as making it easy to remove the setup if I need to service it.

This sounds almost exactly like a Fein running now. I was shocked at how much less the noise is by changing the way I mounted the motors.

Hope this is helpful to someone.

tuck
05-05-2008, 04:29 PM
It's helpful to me, Ed. I'm still struggling to get a grip on all this. Is this a 'series' or a 'parallel' setup?

ed_lang
05-05-2008, 04:53 PM
Parallel at this stage. The way you can tell is both inlets are connected to the same place and both exhaust ports are connected to the same place.

Series is like this.....

INPUT --->(motor one)--->(motor two)---> exhaust.




Parallel is like this......

INPUT --->(motor one)---> exhaust.
INPUT --->(motor two)---> exhaust.
etc...

I hope this helps.

Another way to think about this series and parallel stuff is with a garden hose. Lets say you have three sections of hose. You connect a "Y" to the faucet on your house so you can connect two hoses to it. One for your wife to water flowers while the other is for you to wash her car. Those two hoes are in parallel. Now you need a longer hose to wash her car because she doesn't want you getting soap on her flowers! You connect that third hose to the end of yours and your two hoses are in series. Your series hoses have the same amount of water flowing in each one. Hers is in parallel to yours and she can turn hers on and off and it will not change yours.

Call, email or post here if I can help you are anyone further.
ed

myxpykalix
05-05-2008, 09:37 PM
Geez Ed I didn't know you were a rocket scientist. That thing you made looks like its ready to...3, 2, 1 blast off!!

maginter
05-05-2008, 10:04 PM
Hi guys -

Everything I am seeing looks great! I do have a rather basic question. Why not pick either series or parallel? WHat would be example of when one is better than the other?

Thx

Mark

Brady Watson
05-05-2008, 10:36 PM
Mark,
It depends on the size of the parts you want to hold & the amount of CFM you require for the task at hand. Experience & personal experimentation, is the only guide for this.

A set of vacuum motors running in series will generate less than 2X the rated suction of one motor and approximately the same CFM as ONE vacuum motor by itself. (Read up this thread a bit to get more insight on this) A set of vacuum motors running in parallel will generate the same amount of suction as one motor, but will have 2X the amount of airflow (CFM) than just one motor. Most jobs are fine with 2 motors in parallel with the added CFM. When you start getting into small parts, with smaller kerf widths to leak out vacuum, then the series configuration is beneficial. Again - experimentation is the key here, and the best teacher you will ever know.

-B

beacon14
05-06-2008, 12:33 AM
Mark, Ed's system is an excellent example of what I have been trying to get you to consider. The 4 (or is it 5?) zones each have a valve connecting the table to a length of pipe (the manifold) which is then connected to the motor assembly. The motors could be series, parallel, or 9-15 switchable. Most of the time the motor configuration will not change, just open or close whatever zones you want to work with and get cutting.

ed_lang
05-08-2008, 08:33 AM
David, and all.
My current system is a 5 zone system. I drew a 4 zone system on my 4'X8' table and then divided up the fist zone at 0,0 into two 2'X2' zones.

With my current two motor configuration, I can very easy make another "set" and connect the input of the second set to the exhaust of the fist set and have the series advantages. So far, I have not needed it so I am not moving too fast in that direction.

Ed

dubliner
05-17-2008, 08:41 PM
Hey Guys, pipe question here ~ I'm thinking T fittings will work yet I know Y ftgs. are best in dust collection etc. but when the vacuum is generated then the vortex/turbulence would not really come into play in a hold down vac system, would it?? In other words can I use T's instead of Y's

Gary Campbell
05-17-2008, 08:53 PM
Hey Nev...
Tee's should work fine on a low flow system. When that specific question was posed to Harold in an email, he told me that a wye/45 el combo would have 25% of the restriction of a tee or cross. He also mentioned that is may not be a significant factor in a vac motor system, due to low cfm. Hope this helps.
Gary

dubliner
05-17-2008, 09:07 PM
Gary, my man, how are you!!, I was thinking & hoping that. as the y's would make it a bit bigger than I want. Its like the Blue Man Group already. Thanks for replying Gary.

dana_swift
05-18-2008, 09:02 AM
The difference between a T and a Y is almost none once the system is evacuated. The difference is in the initial evacuation surge when the valves are opened. The closer to laminar flow you can get, the faster the pressure can drop and hold your work down.

This issue is larger if you use vacuum pumps like I do instead of blowers, as the initial evacuation depends on the volume of air that has to be evacuated and the relative capacity of the vacuum accumulator.

I build a vacuum pump check-valve joiner based on Joe Johnson's dog-ball system. That has worked very very well for me currently multiplexing two pumps. Here is his series idea:

http://www.talkshopbot.com/forum/show.cgi?tpc=312&post=67639#POST67639

Because I am working with oil/vane vacuum pumps that get very close to perfect vacuum, series connection has no value at all, as each can create the ideal vacuum. Having the multiplexer just lets me kick in more than one pump if I want higher CFM due to a leak, or to purge the accumulator faster. Once I have 20"+ hg I can shut all but one pump off and the part will stay held down, but my electric bill goes way down.

Speaking of electric bills, I like the vacuum pump approach for my application because I don't need lots of CFM (Currently I can get up to 10 cfm at atmosphereic pressure), but once my parts are pulled into the seals I am careful to make my cuts so that I never break the vacuum, then just one small pump will sustain the vacuum. That means a 1 or 1/2 horse motor running continuously instead of the much larger motors found in blower approaches. Not to mention needing to run multiples of them simultaneously.

Building one of Joe Johnson's dog-ball check valves cost me about $10.00-$15.00 in parts, less than a store bought check valve, and works better for my application.

One final note on my experience, when I shut off the vacuum pumps the accumulator will discharge back to 0" hg in about one minute, so there is some leakage around the dog balls. When I was running one pump alone, when I would shut off the pump it took several days for the vacuum to bleed off. I could save the vacuum from one day to the next! Now I have to re-purge each time in exchange for the higher CFM.

Life is full of trade-off's eh?

D

Gary Campbell
05-18-2008, 11:25 AM
Dana...
Very few of us that must cut thru parts can use the hi-vac low-cfm approach. Even tho I have a similar pump, it will not work at all with a spoilboard/bleederboard on my system. Taking data from this chart for the Ametek motors that I use, combined with failure data from normal cutting and some unscientific tests I have done, I think that flow or CFM may be of more value to most of us than hi vacuum numbers.


351

Using 13.6 as the conversion between InH20 and InHg I propose the following.(as it applies to my system, which has almost identical specs to the Fein) These vac motor pumps have high flow with little or no vacuum, and low flow while developing moderate amounts of vacuum. When we cut thru material, we are most interested in the linear change between flow and vacuum, as having enough vacuum to hold down parts depends on our ability to evacuate the air under them.

Using a 2' by 4' zone with 1 vac motor direct I get the following using a gauge that tests in the plenum near the outlet rather than in a manifold some distance away.

Max vac available: 7.5" Hg
Vac with 3/4 bleeder/spoilboard installed: 1.5" Hg
Vac with spoilboard completely masked: 5.5"Hg
Average vac when cutting: 5" Hg
Avg vac when parts move/fail: +/- 3.5" Hg

Using the chart, I feel the following would hold true:
Thru the unrestricted bleeder I am flowing around 96CFM to maintain 1.5" Hg (= 1.25" orifice)
While holding my parts, I am flowing around 28CFM while maintaining 5"Hg (= .5" orifice)
Hold down fails when flow increases over 45CFM and vac falls below 3.5-4"Hg (>.625 <.75 orifice)
The difference between holding and not is a very fine line. Putting 2 of these motors in parallel should come close to allowing 80 CFM of flow while maintaining close to 5"Hg hold down power.

Using specs from a regen blower that I wish I could afford at this time but cant, (10 HP 388CFM max 8"Hg max ,shows the following:
These regen blowers will hold 7.5"Hg vacuum while flowing 120CFM. This is why we would all want one. Unfortunately myself, along with many others cannot afford this 3 phase pump.

This is why Brady started this thread. He planted the seeds to have a relatively inexpensive system that will get the flow needed to hold down parts. Coupling that with the ability to have high vac numbers when needed is awesome!

On a side note, I do think that flow is as important in a vac system as leakage. As we cut we will need flow to maintain vacuum. Valves, elbows and pipe distance all factor in. Especially when using pumps with marginal capacities, such as my own. So as Neville does above, pay attention to fittings and layout as to not build in any uneeded restrictions or leaks.
Gary

bill.young
05-18-2008, 12:49 PM
Hi guys,

Gary will be doing a column for the ShopBot website on his custom ShopBot hacks and mods, and the first couple of articles are on his vacuum setup...they're really good. Unfortunately I've been VERY slow in getting them online but as soon as I get a break from cutting the house parts for the Museum of Modern Art show I promise I'll get them posted, along with Rob Bell's new column "ShopBot Magic" and a neat article by Paul Zank on working on the Home Makeover projects.

Bill

Gary Campbell
05-31-2008, 10:20 AM
A few updates..
Gary Jr and I did some additional testing on Friday. Most of this was done using a 12" square piece of PVC with a vacuum port drilled in the center in which we installed a cheapie vacuum gauge from the auto parts store. This setup allowed us to measure the vacuum actually available to the part on the TOP of the spoilboard.

Our last job was a 4 by 8 sheet that had around 100 2" and 6" letters cut out of it. Our first tests were done on top of these numerous 1/8" by .010+ deep "tracks" and a little cutting dust.

We then surfaced the spoilboard, took some readings and taped the edges to see if we had perimeter leakage.

Using the in plenum and on spoilboard gauges we found the following:
Before surfacing: Open Spoilboard (in) 4.5 inHg
Spoilboard completely masked: 6 inHg
Top reading near center 3 inHg

After surfacing: (2.5" bit, .030 cut, 2" stepover, 7ips)
Open Spoilboard: 3.5 inHg
Completely masked: 6.5 inHg
Reading on top near port: 4.5 inHg
Reading on top at fathest point from port: 4 inHg
Reading on top with hole 1" from spoilboard edge: 3.5 inHg
We then started sliding our plexiglass masks apart to see how an open area would affect vacuum on the part. It took an open area of 1 foot square before either gauge lost .5 inHg.

We surmised the following:
Our edges were not leaking.
The 3/4 (now surfaced to near 5/8") spoilboard has much more restriction to flow than the 1/2" (surfaced to 3/8") than was tested earlier.
The dusty and cut up spoilboard was costing us both flow and leakage. The vacuum loss was 1.5 to 2 inHg from the plenum to spoilboard top. This may be an advantage when cutting thru parts.
In a cutting situation, even when our in plenum gauge showed near 6", there was actually only 3.5" on the part.
When set over the "tracks", blue masking tape around the edges of the gauge sheet increased vacuum by an inch.
Our plenum design may be flawed as longer distance from the port resulted in lower vacuum.
I wish that I had the top side gauge with the 1/2" spoilboard to see if I actually had more usable vacuum on top of the spoilboard.
IF we deduct the spoilboard overhead from our numbers in the post above, it becomes very easy to see why we were having parts move at 3.5 to 4 inHg.
The specs from the "9-15" motors show that close to 6 inHg+ should be available at the part!

There is no new info here. All of this can be found in forum posts I found going back to 2005 and Brady's column. Unfortuanately there is a snipet here and there. Due to the interest in this continuing post, I am trying to combine some of this with our testing to aid those that are considering which vacuum source they may use.
Gary

tkovacs
06-22-2008, 04:58 PM
Hi folks,
I want to share my variation of the open source design. I am fortunate to have separate storage space next to my shop. The bot is adjacent to the wall separating the two spaces. The vac system is wall mounted on the storage side of the wall. The design is easy to reconfigure from series to parallel by moving the second vac between two ports.
My original thought was to enclose this a bit more but after feeling how hot these vacs get I think it is going to stay this way.

Terry


352
Series configuration


353
Series configuration with the blank off port removed


354
Parallel configuration

dana_swift
06-22-2008, 06:06 PM
Terry- the design you came up with is beautiful in its simplicity!

Well done! Do you have pressure readings on your implementation?

Thanks-

D

tkovacs
06-23-2008, 09:53 AM
Thanks Dana, and thanks to all who have shared their ideas here, I certainly would not have gone down this path without the great ideas I have learned here.

Below are some data from my eight zone table. Each zone is 23" square and the bleeder is 1/4" MDF that has been surfaced on one side. The zero zone measurement was taken at the table top with all the zones blanked off (closed).
The other measurements were taken with from the surface of the bleeder board with a port mounted in the center of a 4" square piece of 1/2" MDF. This puck has a through hole for the measurement fitting so the value should be representative of the bleeder - work piece interface.

My interpretation is that for this configuration unless there will be the equivalent of ~1.5 zones of open bleeder board the series configuration always wins.
I would be interested in how others might interpret the data.


355

paco
06-23-2008, 10:16 AM
Well that is simple but efficient system! Those data are very interesting.

quote:...and the bleeder is 1/4" MDF that has been surfaced on one side.
Grrr! Hmmm... look like I may have some homework to do!

Brady must be kinda proud to see where this open source vacuum hold down project has gone so far.

harryball
06-23-2008, 10:54 AM
OK... this is the first time I've seen the cfm vs vac on a chart like this... notice as leakage increases how the higher cfm solution actually holds more vac than the higher vac solution.

Just talking out loud. ;-)

With the painfully simple system Terry has created and the cost effectiveness of the pumps I think this is a great option.

/RB

ed_lang
06-23-2008, 11:57 AM
Terry,

That is the best version I have seen to date.

Super job.

If I ever need to run my motors in series, I'll be making your version. So far, I have not needed more vacuum.

gerald_martin
06-23-2008, 01:09 PM
Terry: Ingenious! Would it be possible to install a 3rd motor on the other (parallel)port and have a "hybrid" system that has the advantages of high cfm plus additional vacuum? "talking out loud"....

Gerald

tkovacs
06-23-2008, 02:02 PM
Thanks for the comments!

Gerald - I don't that adding the third motor as you suggested would be helpful - but I'm not certain.

As for CFM vs vac. RB got me to thinking. I have no way to measure cfm but if we assume that cfm is proportional to the surface area of the bleeder board (twice the bleeder board area under the same vacuum => twice the CFM) and also proportional to the vacuum (twice the vacuum with the same bleeder board area => twice the CFM) then it is possible to calculate a relative CFM.

Then here are the CFM numbers relative to one zone in series (one zone in series is defined as ==1).


356

Interesting numbers but keep in mind that the low vacuum numbers are at the low end of the gauge limits and probably are less accurate.

harryball
06-23-2008, 02:40 PM
I've always thought that is would be better to have 8" of vac with massive cfm (300 to 400+) than to have 14" of vac with 120 cfm. My reasoning is that as you make more through cuts the leaks created are "forgiven" by the higher cfm which maintains an overall higher holding power than the 14"/120cfm vac system in the same situation. The graph you did seems to illustrate exactly that fact. I'd be intersted to see the same graph with 8" of vac but 1, 2 and 3 pumps in parallel leaving the only reason for increased vac to be the "forgiveness" of higher cfm. I'm not sure if that makes sense or not but then I'm not often sure if I make sense anyway.

It seems that cfm is much cheaper than "vac as well. I think it would be perfectly reasonable to run 3 of these pumps together to achieve 8" of vac with high cfm. Sounds like a project coming on... if I just had Terry's empty storage room next door :-)

/RB

Gary Campbell
06-23-2008, 05:13 PM
Terry...
NICE JOB! Simple and sweet!
I have a couple questions about your second chart, using data from the first chart as given.
1) Wouldn't the CFM have to increase more as the vacuum decreases? All cfm/vac data I have seen for this type of motor shows this, however vac on top of the bleeder may not be anywhere near as inversely linear as mfgr test data.
2) Do you have a vac gauge in the manifold or piping between the plenum & motor(s)? The reason I ask is, I assume Ward B. has data on the motors and cfm could be determined from the chart based on the vac developed at the motor intake.

Your testing is very interesting to me as I am doing a very similar setup on my system. I am not going to do the series/parallel testing for a while as there has been a bump or 2 in the road and funds are not so loose at the moment. I have however, purchased an Ametek 0-250 CFM flowmeter that I can incorporate into the testing. My salesman at DixiePly has donated a 1/2 dozen sheets of diferent materials to do flow testing on. So keep testing and post the results. I will do the same.
Gary

tkovacs
06-23-2008, 07:20 PM
Gary -
Thanks!
As for:
1) I presume those pressure vs CFM charts are for pressure measurements made at the vacuum intake. The pressure readings in the chart (aside from the zero zone reading) were taken on the top side of the bleeder board.
2) no I don't at present have a vac gauge between the motor and plenum - would be a good idea though.

Terry

Gary Campbell
06-23-2008, 08:04 PM
Terry..
I have been using a gauge in both places for the testing I am doing. My above spoilboard gauge is on a 12" square piece of PVC foam... for now. I have noticed a fairly substantial differential between the 2 gauges, but dont have enough data to see if the spoilboard loss is a constant based on area, a percentage of the vacuum, a constant number based on porousity or thickness of the board, or most likey, a combination of all.

Some of the testing I have done is validation. I have set up my flowmeter using the same conditions as the mfgr tests... vacuum and cfm readings with different size orifices in the pipe. I am getting results that are within 2-3% of mfgr data. I hope this means that both the flowmeter and the mfgr data is accurate.

Assuming that the data for the motor is accurate, a vac gauge near your motor would yield the CFM by cross referencing with the vac number.
Gary

tkovacs
06-24-2008, 08:06 AM
Another interesting little thing. Under the assumption that the max CFM is proportional to the max blank off vacuum the series/parallel ratio of the blank off vacs is 13.5/8.2 = 1.6 which is about where the parallel config maxes out. Nice when the numbers work out...

Brady Watson
06-24-2008, 09:11 AM
Looks great, Terry. Thanks for posting your work!

-B

ed_lang
06-24-2008, 10:38 AM
For those of you thinking about putting three motors on this setup think about this.... When I ran one Sears shop vac I had less vacuum than one Fein vacuum could product. I added a Fein and ran it and the Sears together. The Fein sucked air past the Sears in reverse so in reality, the Sears caused me to have less vacuum than if I removed it. Then I put the second Fein in place of the Sears and all was well. So, if you put one motor on the system and then two in series next to the one motor, I expect you will suck air backwards past the one motor only causing you to have less vacuum than running only one motor alone.

Something to think about.

tkovacs
06-24-2008, 11:05 AM
Ed - I think you are correct.

harryball
06-24-2008, 01:39 PM
That would be correct. You would need all three in series or all three in parallel to get the desired effect of high vac or high cfm. Now... if you have 4 motors arranged with 2 series sets in parallel...

Here's an idea you guys can chew on...


Two motors in series with a valve that changes them to parallel when vac pressure drops below 8 ips. When cfm is not important, opt for high vac. When cfm becomes important (when your vac is dropping below 8 ips) crank up the cfm's.

/RB

erik_f
07-11-2008, 10:34 AM
should be able to be done with a couple simple check valves?

john_l
07-11-2008, 12:16 PM
Good idea.

Just to follow up... I still use my parallel setup "almost" daily. Usually a couple hours but sometimes as much as 10-12 hours in a day, in an un- air conditioned shop.

I just took the covers off to check things out. Still no problems with the vacs. I just clamped the ameter on and they are still drawing the same amount of amperage as when new.

tkovacs
07-12-2008, 08:26 AM
Good information. Has anyone had one of these vacs fail or degrade? What was the failure mode?

Gary Campbell
07-12-2008, 03:35 PM
Terry..
I have a different model of Ametek motor (4 or them) and Zone 1 has been on virtually every hour that the Bot has run for 15 months. My guess is 600 hrs+ and no problem
Gary

32mmcabinet
08-10-2008, 02:43 AM
I'm very new to all this. The vast majority ot the work I will be doing on my bot is cutting cabinet box parts from 3/4" sheet goods (tops/bottoms/sides/stretchers etc.) Would I better off going with a parallel or series setup?

erik_f
08-10-2008, 11:22 AM
The idea behind this is that you can have a setup that does both. I plumbed mine for parallel use only. I felt with the help of Ed Lang that I would have plenty of vacuum with the parallel set up. If I decided to change things up...PVC pipe is cheap.

Gary Campbell
08-10-2008, 01:50 PM
32mm...
If you are THRU cutting nested parts out of sheetgoods, I would recommend a parallel setup. I personally would use 4 motors in parallel to insure adequate vacuum for smaller parts like spreaders and drawer fronts when cutting from 4 by 8 sheets.
I posted some vac numbers for loosely nested parts here: (single motor per zone) http://www.talkshopbot.com/forum/messages/28/32459.html?1217780528
Gary

erik_f
08-11-2008, 12:22 PM
Finally getting close to finishing my set up. Here are some pics even though I'm not quite done yet. The most nerve racking part was boring the 2" holes through the BT's aluminum table.

erik_f
08-11-2008, 12:35 PM
Here are some pics. I decided to make the vacuum table pattern round instead of square and used a ball nose bit to cut it for smoothness and the least amount of sharp edges. Also included a pic of my parallel only vac set up using the open source as my guide.

357
358
359
360

32mmcabinet
08-11-2008, 04:29 PM
Eric and Gary, thanks for the replies. I think I will start with the 4 motors in a parallel set. This has been a great thread.

ed_lang
08-12-2008, 08:06 AM
Erik,

I have been using my "new plenum" for a couple of weeks now and love it. I did the same thing, but I cut mine in baltic birch not plastic. I used an EM and not the round nose bit. My table is 4' X 8' and I went with one zone (entire table) and four motors. I did not glue down the bleeder/spoilboard but did use the metal duct tape from Lowes that Bill Young told me about. I also bought a tap and drilled a hold in the support board all the way to the plenun and installed a hose to a wall mounted vacuum guage like Jay Wyant did at his shop. I am getting much better results than I ever had before I think. The only down side to my system now is I have to run all four motors all of the time. I mounted the motors directly to the bottom of the support board by making donuts that fit the vacuum motors and using T nuts and all thread rod to bolt the motors up after the donuts are glued and screwed to the bottom of the support board. I did put a gasket between the motor and board. I have not taken pictures yet, but will do so and post. I also have the posts close to the openings farther away than you do as I wanted to have no restriction at the port. I also cut a three inch hole which is overkill I think, as well as chamfer the top edge so there would not be a 90* bend there as well.

Keep us posted on how you like yours.

erik_f
08-12-2008, 10:35 AM
I was thinking about putting a chamfer or radius at the port to smooth flow into the port. I decided not to only because I only have a 1/4" of material left to work with and didn't really think a radius that small would make much of a change. Also I have used two ports for my single zone. The real bottle neck of the design is the 1x3" aluminum tube that will be used to connect the bottom of the table to the vacuum hose (thanks Brady). Inside of the aluminum tube measures .74 x 2.75. This gives an area of 2.06 square inches...so using two surpasses the area of the 2" pipe of 3.14 square inches by a full 25%. 3" pipe would give an area of 7.06 square inches which I don't think is over kill. For me though I used 2" pipe for my vacuum pumps PVC so I found no need at this point to use larger pipe, but did not want to go any smaller than the area of the 2". Also with the BT48, to get larger pipe to the table, the only option is to go with wider tubing and keep with the 1" depth (because of the moving table). To get anywhere near the surface area of a 3" pipe I would end up having to go with two 1x5" aluminum inlet tubes. This would create all sorts of other issues with mounting the tubes. Overall I'm very pleased with how the design is coming along. I really want to thank you (Ed Lang) and Brady for directly helping me out with this, as well as everyone else that has posted their great ideas. I assume that you decided to run all four motors in parallel to gain more cfm? I'm curious to see with your new vac gauge how well the added cfm holds vacuum as you cut through material. Sounds like you're pretty happy with it though.

erik_f
08-28-2008, 04:48 AM
Finally have got this thing to the point where I can use it! Woo hoo! Ok...now...when I surfaced the ultra light MDF it took quite a bow to it. So much so that it wouldn't hold flat to the table until I flipped it over to the non-milled side. Problem with that is it puts the table out of wack again. Is it normal to have to mill both sides of the ULDF? I was hoping to not have to glue it down to the plenum and only hold it in place with vacuum. Sorry no pics as of yet!

john_l
08-28-2008, 06:53 AM
I did the same with trupan and was worried about it cupping before I flipped it. I let the surfacing process make a few revolutions around the outside of the sheet to let the bit work itself away from the edge areas and then I went around and used some spring clamps to hold the sheet down until it was all finished up. This worked well for me.

32mmcabinet
08-29-2008, 03:42 AM
Would the motor's intake and exhaust be able to pull/push through acoustic foam (2 1/2")?

erik_f
08-29-2008, 09:12 AM
If it is just regular open cell foam I don't see why not.