[Phife]

If you are going to use the Gast pumps, I recommend trying out the Thomas brand pumps.

I have 3 on my gasketed vacuum table, I can use 1 or all 3 at the same time, they have similar specs as the Gast (6.6CFM open and 27.7"HG) but only cost around $50!

So you could buy a whole bunch of these for the same price as 1 Gast.

I have 4, only 3 hooked up and 1 backup. Ive been using the 3 for about 100H runtime so far and no issues!

Keep in mind that these are used pumps, but for the price they cannot be beat!

Thomas Compressor Vacuum Pump 2650 2660 Pond Aerate | eBay

there are several other listing on ebay, just search Thomas Vacuum pump, go for the 2600 series.

Hope this helps.

[rowbare]

Check out the ShopBot forums. There are a few threads there on DIY pumps build from commercial vacuum cleaner motors. Something like that might be a good first stage pump to get the bulk of the air out and suck down the sheet. After you could switch to a pump with less volume but more suction.

Also check out CNCCookbook. There was an article posted recently about doing some carbon fibre work. There are a few pics of the vacuum system used for the bagging.

bob

[LeeWay]

There was also a thread somewhere where a guy reversed the valves in an air compressor to make it pull vacuum instead. I don't recall where I saw it, but it was on a forum. Here there or some other one. Not much help as it's been a few years, but I thought that was rather cool.

[Phife]

There was also a thread somewhere where a guy reversed the valves in an air compressor to make it pull vacuum instead. I don't recall where I saw it, but it was on a forum. Here there or some other one. Not much help as it's been a few years, but I thought that was rather cool.

A compressor can work, but its not designed for vacuum so the valves get damaged fairly quickly, I used one at the start and it didnt last long.

I tried to take it apart and reverse the valves but it wasnt possible with the compressor I had, I think you can do it on some, but most compressors you wont be able to reverse the valves.

You do get suction on the intake port and you can reverse the plumbing so it pulls a vacuum instead of compressing but dont expect it to last long if you cannot reverse the reed valves.

[diyengineer]

Wow that was a good find. I will look into that more. He says he even offers the rebuild kits for $20 bucks! Have you bought the rebuild kit? Any pictures of your setup?

Thomas Compressor Rebuild Kit 2619 2639 2650 2660 | eBay

I would feel better buying a rebuild kit for each and going through the top end at least. Might as well its cheap enough.

Seems like i have 2 options:

This..
Thomas Compressor 2660 Model Vacuum / Compressor | eBay

or..

This..
Thomas Compressor Vacuum Pump 2650 2660 Pond Aerate | eBay

I may have to go that route. That would be interesting.

If you are going to use the Gast pumps, I recommend trying out the Thomas brand pumps.

I have 3 on my gasketed vacuum table, I can use 1 or all 3 at the same time, they have similar specs as the Gast (6.6CFM open and 27.7"HG) but only cost around $50!

So you could buy a whole bunch of these for the same price as 1 Gast.

I have 4, only 3 hooked up and 1 backup. Ive been using the 3 for about 100H runtime so far and no issues!

Keep in mind that these are used pumps, but for the price they cannot be beat!

Thomas Compressor Vacuum Pump 2650 2660 Pond Aerate | eBay

there are several other listing on ebay, just search Thomas Vacuum pump, go for the 2600 series.

Hope this helps.

[diyengineer]

Sch 40 4" PVC 20' (burst pressure of 220psi) $42.61

Volume: (20' section) (pi x r^2 x h)
4" - 3014 cubic inches

Cubic inches to gallons: (1 cubic inch = .00432)
4"- 13.02

Price per Cubic Inch:
4"- $ .014

Looks like the 4" pipe is a little more cost effective.

I was possibly thinking of only using 1 piece giving me a 13 gallon reservoir, and using a couple shop vacs to quickly evacuate the air, then close them off with valves and let my vacuum pumps take over. This would evacuate a lot of the air, without needing a monstrous reservoir tank. If i go the Thomas pump route, i will buy new top end rebuild kits for them all and possibly use 4-6 pumps. Waiting to hear back from the ebay seller about a bulk/discount rate.

[Phife]

I'll snap some pictures for you tomorrow, I also use 4" PVC pipe about 40" long as my reservoir , I had a smaller one when I first built my vacuum table, and honestly I dont notice much of a difference using a larger reservoir.

[diyengineer]

I'll snap some pictures for you tomorrow, I also use 4" PVC pipe about 40" long as my reservoir , I had a smaller one when I first built my vacuum table, and honestly I dont notice much of a difference using a larger reservoir.

Phife-

Thanks for the pictures, anyone else can feel free to load up some pics of there systems. Anything will help

[diyengineer]

I found this website:
~~ Thomas 2650 and Thomas 2660 Rebuild Kit and Parts ~~

They offer FULL rebuild kits, including gaskets, valves, sleeves and bearings for less than $25 dollars. Can't go wrong.

I contacted the ebay seller and he gave me a bulk discount quote. $40 dollars a pump + 15.95 for shipping. I said i wanted 6 pumps.

That is about $336 dollars for all those pumps. crazy good deal.

I then will order the full rebuild kit for each pump. That should be right around $180 dollars.

For $500 dollars i will have 6 fully rebuilt pumps, that's roughly 85 bucks a pump.

Major thanks to Phife!!!!

Tomorrow i go to pickup my 4" tube

[Jay C]

There was also a thread somewhere where a guy reversed the valves in an air compressor to make it pull vacuum instead. I don't recall where I saw it, but it was on a forum. Here there or some other one. Not much help as it's been a few years, but I thought that was rather cool.

That was Greolt (Greg) in Australia that did that.

[Geof]

There was also a thread somewhere where a guy reversed the valves in an air compressor to make it pull vacuum instead. I don't recall where I saw it, but it was on a forum. Here there or some other one. Not much help as it's been a few years, but I thought that was rather cool.

This one? Greolt did do it first.

http://www.cnczone.com/forums/work_f...ompressor.html

[Phife]

Heres some pictures of my setup, I have a 2'x4' vacuum table made from 1" HDPE, it is bolted down to the 2" thick MDF table I have in several places to ensure uniform flatness as the HDPE will want to cup once the grid is machined into it.

I drilled a grid on the bottom side of the HDPE for 1/4"-20 insert nuts
The top gets surfaced and a grid is machined.

The top is 1/4x1/4 grid that also has insert nuts that I can use when I want to clamp something to the table instead of vacuum.

I use 1/4" x 5/16" Neoprene rubber that I get from a local guy in 50ft rolls. Its cheap, $4/roll

I use the bare HDPE table for job that do not get cut through, and for jobs that do I use a dedicated spoil board with 1/16" PSA backed neoprene to hold the vacuum in, I also use the Vinyl covered MDF boards sold at Home depot as it saves me from having to seal the dedicated spoil board.

Leaks are your enemy, the 3 pumps can handle small leaks but they are not 20HP vacuum pumps, they can only move so much air, you really have to keep and eye on the pressure gauges, so I have 2 that I can see easily.

I have 6 vacuum ports on my table that each has a valve so I can open one or all of them depending on the job.

I also want to point out that 3 pumps is pretty much the max you can run on one 110v 15A outlet, you can get away with 4 but just be aware that you have to run these pumps on their own circuit and not on the same one your CNC or Router is on.

I plan on building an enclosure for my pumps sometime soon as well. They are noisy.

The PVC reservoir has a screw off lid that allows me to clean the filter that is inside, I have a large particle pre filter made from some cheap furnace filter and then the long section has a rolled up towel to filter out smaller particles. Keep the dust out of the pumps.

Also I have 2 gauges one for Reservoir pressure and one for table pressure.

Each pump has a check valve so they dont fight each other and helps keep the pressure off them when one is not running but another is.

I do not have any rebuild kits and I think mine came rebuilt because they were very clean and when I took one apart the seals looked new. So maybe only buy a kit or two. I have over 100H on these pumps with no signs of quitting.

Hope this helps you out, feel free to ask if you guys have any questions.

[diyengineer]

I just picked up a 20' section of 4" pipe today!

Thanks for the pictures wow! That is exactly what i am after. Very Very cool!!!

I plan on running a dedicated power line from my sub panel for the 6 pumps. I figure a 13 gallon storage capacity should suffice (hopefully).

Ill examine your pictures more closely when i get home, im currently on my cell phone!

thanks again!!

Heres some pictures of my setup, I have a 2'x4' vacuum table made from 1" HDPE, it is bolted down to the 2" thick MDF table I have in several places to ensure uniform flatness as the HDPE will want to cup once the grid is machined into it.

I drilled a grid on the bottom side of the HDPE for 1/4"-20 insert nuts
The top gets surfaced and a grid is machined.

The top is 1/4x1/4 grid that also has insert nuts that I can use when I want to clamp something to the table instead of vacuum.

I use 1/4" x 5/16" Neoprene rubber that I get from a local guy in 50ft rolls. Its cheap, $4/roll

I use the bare HDPE table for job that do not get cut through, and for jobs that do I use a dedicated spoil board with 1/16" PSA backed neoprene to hold the vacuum in, I also use the Vinyl covered MDF boards sold at Home depot as it saves me from having to seal the dedicated spoil board.

Leaks are your enemy, the 3 pumps can handle small leaks but they are not 20HP vacuum pumps, they can only move so much air, you really have to keep and eye on the pressure gauges, so I have 2 that I can see easily.

I have 6 vacuum ports on my table that each has a valve so I can open one or all of them depending on the job.

I also want to point out that 3 pumps is pretty much the max you can run on one 110v 15A outlet, you can get away with 4 but just be aware that you have to run these pumps on their own circuit and not on the same one your CNC or Router is on.

I plan on building an enclosure for my pumps sometime soon as well. They are noisy.

The PVC reservoir has a screw off lid that allows me to clean the filter that is inside, I have a large particle pre filter made from some cheap furnace filter and then the long section has a rolled up towel to filter out smaller particles. Keep the dust out of the pumps.

Also I have 2 gauges one for Reservoir pressure and one for table pressure.

Each pump has a check valve so they dont fight each other and helps keep the pressure off them when one is not running but another is.

I do not have any rebuild kits and I think mine came rebuilt because they were very clean and when I took one apart the seals looked new. So maybe only buy a kit or two. I have over 100H on these pumps with no signs of quitting.

Hope this helps you out, feel free to ask if you guys have any questions.

[diyengineer]

If anyone is interested i've uploaded the entire PDF file to the Joes Woodworking vacuum press (open source). I have read it through about 10 times now for a full understanding of how one of these vacuum systems should work. They are actually quite simple when its so nicely laid out in front of you in a pdf document.

I've uploaded 4 different schematics of how i could pipe this thing. 2 use a multi tank system, and the other 2 all share a single tank. I have clustered the vacuum pumps together in 3 groups of 2. I dont know which system will be more versatile.

Also, i used the mac valves (which i would have to buy) in 2 of the drawings. I figured since this valve just has to dump vacuum from behind a check valve i could use up some of the six honeywell valves i have laying around. There 24V so i would need a relay and a transformer but it would save some $ for me at least.

If anyone has any other ideas on how to route or cluster the 6 pumps for best performance let me know. I will be running a line from my sub panel and a new breaker for these pumps.

I went ahead and ordered 6 units. $405 dollars. Not bad for $67.50 each including shipping.

http://myworld.ebay.com/bluelooneym/...id=p4340.l2559

Thomas Compressor 2660 Model Vacuum / Compressor - eBay (item 270701962819 end time May-05-11 10:56:14 PDT)

[Phife]

I see several issues with your designs, First off, each pump should have its own check valve, right now you have them in pairs but if you are only running one of the pumps in the pair it will be pulling on the other pump next to it.

I dont use the sub resivour on my system, no issues because the check valves unload the vacuum pressure from the pumps when they are not on.

Keep in mind that the Joe woodworker designs are ment for vacuum bagging, and veneer work, they are over complicated for a vacuum table design, you dont need mac valves and vacuum controllers for a vacuum table.

What size hose are you going to use to connect everything? I use 3/8" hose, I like your Main 1 no mac valves design the best, but I would put the filters farther up the line, at least before the check valve, you dont want dust or debris getting into your check valve, or vacuum controller.

[diyengineer]

I took your recommendations into consideration and revised it down a bit. No need to complicate things and spend extra money for things i wont use. Like you said, vacuum bagging usually takes hours,or even days! In those circumstances i would want the pumps to be able to cycle them selves so they don't run and kill themselves over the loooooong period of time. But for vacuum clamping i want them on all the time, and honestly they wont be running for that extreme amount of time. So that all makes sense. Individual check valves also make sense.

Do you use a vacuum controller (pressure switch)? I was just going to say its no big deal for me to turn them on and off, but once all the pumps reach FULL vacuum, is it ok for them to continue to try and pump or MUST they shut off because they will self destruct?

I placed the filters on the forefront of it all. Like you said, this will keep the system clean of debris. I will make a little control panel so i can actuate the electric solenoids and choose which ones i want. The reason i have 3 filters is because the ones that JOE sells are only good up to 10CFM. i figured if each pump can open air 5cfm i didn't want to limit it at all. I also included mufflers on each pump, i found online it can kill the noise by 23 decibels and not affect performance whatsoever.

As far as tubing i don't know yet maybe 3/8" or 1/2" on it all. What is the deal with "soft" tubing? Which tubes will crush under vacuum and which wont?

Also slimmed down the reservoir tank to a single 48" piece. That is roughly 2.5 gallons. You think that will be adequate? I have 20' of pipe but figured why not slim it down a hair.

Let me know what you think.

[diyengineer]

For the electrical, i was going to run Three 2 pole magnetic contactors. Each contactor would have a 24V coil. All my half inch valves also use 24V AC to actuate. I would use a 24V transformer and use simple toggle switches between each 24V coil and contactor to actuate the magnetic contactor on and off.

On my switch panel, i could turn on 2 compressors at a time. This would let me use 2, 4, or 6 compressors. I could also actuate which valves i want to use, 1,2, or 3 1/2" valves. This would let me use all 3 valves for a large fixture, or 1 valve for a smaller fixture. (maybe that is overkill? Could one 1/2" valve flow enough cfm?)

[diyengineer]

Also i found a few things i need from joe wood worker, but the price of the check valves is huge. Anyone else know of any cheaper check valves? I mean $95 dollars for 6 check valves is almost a crime. Are they special for vacuum or can any check valve work?

Could these work?
http://cgi.ebay.com/Brass-Check-Valv...item43a18fb443

[Phife]

I dont use any vacuum controllers, but you could use the controllers instead of manual switches to turn on your pumps, upon powerup all pumps would start, once say 8"HG is reached, 2 of 6 pumps turn off, once 12"HG is reached 4 of 6 pumps are off, This would allow the pumps to turn back on automatically if you develop a leak.

But again, theres a more cost involved in it, and really I never had a need for it, I usually run all my pumps for an entire job, some jobs have taken 5+Hours and the pumps never failed or got too hot.

These pumps can work under full vacuum with nothing flowing through, although you will have a small amount of air still flowing due to leaks.

Mufflers are a good idea, i was planning on adding them to my pumps soon.

I use 3/8" ID tubing, the ports on the pumps are only 1/4" NPT so you could still use 1/2" but I see no reason, 3/8" flows more than enough air. I use barb connectors on all the hose connections.

The hose I use has nylon woven in between the hose walls, its fairly thick, the cheap PVC stuff with no nylon would certainly collapse under vacuum, but this stuff doesnt at all.

I only have around 38" of 4" pipe for my resivour and I see no problems, I had a smaller tank and I never noticed a difference, Im sure 48" is plenty.

I only paid about $4 for my check valves, they were for a pressure washer and work fine, Im sure the cheaper ebay ones will work just fine.


Good Luck!

[diyengineer]

Ya, i think ill stick with no vacuum controllers and using the manual switches.

I guess i'm limited by 1/4" npt as you said, no point going much larger unless its cheaper, good point. Maybe i will use a 40" pipe. then i can mount all the pumps side by side and it will take up less room.

Does anyone ever incorporate some kind of safety switch linked to estop? Like if the vacuum dropped below a certain level it would turn on estop? Or say if your work piece actually moved, it would alert estop? If it was a long run of nested parts and you wanted to make the system a bit smarter that would be cool. I guess that will be some food for thought later on

Also since i have 6 valves laying around, i was going to use 3 valves for the output to the fixture. Well when it comes time to release the fixture it may take a while if its a good seal to release, i can use the other 3 valves i have for a fixture dump valve releasing all the vacuum on demand. This would allow for really fast swaps of fixtures or pieces. I already have them, why not? :P

I dont use any vacuum controllers, but you could use the controllers instead of manual switches to turn on your pumps, upon powerup all pumps would start, once say 8"HG is reached, 2 of 6 pumps turn off, once 12"HG is reached 4 of 6 pumps are off, This would allow the pumps to turn back on automatically if you develop a leak.

But again, theres a more cost involved in it, and really I never had a need for it, I usually run all my pumps for an entire job, some jobs have taken 5+Hours and the pumps never failed or got too hot.

These pumps can work under full vacuum with nothing flowing through, although you will have a small amount of air still flowing due to leaks.

Mufflers are a good idea, i was planning on adding them to my pumps soon.

I use 3/8" ID tubing, the ports on the pumps are only 1/4" NPT so you could still use 1/2" but I see no reason, 3/8" flows more than enough air. I use barb connectors on all the hose connections.

The hose I use has nylon woven in between the hose walls, its fairly thick, the cheap PVC stuff with no nylon would certainly collapse under vacuum, but this stuff doesnt at all.

I only have around 38" of 4" pipe for my resivour and I see no problems, I had a smaller tank and I never noticed a difference, Im sure 48" is plenty.

I only paid about $4 for my check valves, they were for a pressure washer and work fine, Im sure the cheaper ebay ones will work just fine.


Good Luck!