Would this Vac work?

[jeffp]

I am looking at a couple of used Shopbots to bring into our shop and cut out cabinet parts. I really want to use a vac hold down, as there may be many parts coming out of one sheet. I see that many guys have found other means (other than the 15HP 3 phase) to hold down their work. For the guys out there that have tried, would it work to use a vacuum pump (or pumps) like what is used to pump down a residential a/c unit. They pump at about 28hg at about 4.5 to 5 cfm. If a guy took two of these, and routed them through a holding tank of some kind, do you think that it would work? I know that this issue has been beat to death (I have looked at all the old threads), but I do not see where anybody has tried this. They run off 110, which would be a big benefit.
Thanks in advance

[billp]

Jeff,
There are a number of people using similar systems. In some cases they use the moveable pods/pucks, while others have a stationary system on their table.
The deciding factor to determine which system is more applicable would be; do you cut out the SAME parts over and over? If so a "dedicated table"with a system of vacuum ports running underneath the positions of each component would be easy to design. Gasketing would insure a tight fit, and changing out sheet goods would be fast and accurate. Cabinet parts are "usually" large enough to allow a setup such as this.
If you cut different parts all the time, then either the pod system, OR smaller, changeable tables that could be fitted on top of your spoil board depending on the job at hand might be a better choice.
In either case one of the main things to consider would be; how flat is your stock material? If it is not flat then you'll have to use mechanical aids in the initial hold down phase (or as some people have done, plumb in a higher CFM unit such as a Shopvac or Fein vacuum unit for the intial sucking...).
Also consider a multi zone setup which would use one of the Shopvac systems mentioned above, with each zone having it's own vacuum source. While it would cost a little more than the smaller,higher suction pumps, it might be more versatile.

[jeffp]

I appreciate your input. Most of what we would be cutting is 4x8 sheets of 3/4 melamine with a particleboard substrate into cabinet parts that would include pieces as small as 4"X12". If I were doing this myself, I would not have as many concerns, but I want to make it as easy as possible for the shop guys to handle. If I can stay away from the 3 phase power, it would nbe a good thing.
Thanks for your reply, and thanks for the contributions that you have made to this forum. I have been reading a ton on these machines, and your perspective is always appreciated.

[kivimagi]

Jeff,

I have a bit of experience with this. I have an old/heavy 1/2 hp vacuum pump, which does a nice job of creating vacuum. I hooked up a 35-50 gallon propane tank to it, and plumbed that into my dedicated vaccum grid.

It pulled the sheet very flat, and held it very strongly. I did however have issues with having a large enough holding tank, so that it could pull the sheet flat, and have enough of a seal to begin to build the pressure back.(I purchased all my stuff from joewoodworker.com, which is also all over this board)

I plan to add one more propane tank soon, and give it another shot. Will post my results, as this is a very cheap system. Gerald's post about using the truck brake tanks, could save even more money.

If you are cutting all the way through the melamine, I don't think you'll have good success unless you use the pods or gasketing.

Hope it helps

[jeffp]

The plan is to cut all of the way through the melamine. I don't know how I could gasket for it, since every sheet would have different parts cut out of it. I think that this will take some learning curve.