[RCjunkie]

What is the best way to have a Vacuum table?
I have 1 now and but it does not work the best. I use UL MDF weight is 28# per sheet. and use 2 fien shop vac.

[RCjunkie]

I also for got to say it is a 96" x 48" table

[txcncman]

Change to a high CFM vacuum pump. A shop vacuum will never give the performance as a vacuum pump.

[keebler303]

Ha ha ha ha ha ha

A good vacuum system on a 4x8 table will be something like 30, 40 maybe even 50 HP. A shopvac isn't going to cut it. You need to either go to something like a "pod" type setup where the vacuum is well sealed and only where you want it, or you need a lot more sucking power. There are lots of threads about it here if you search around.

Good luck
Matt

[RCjunkie]

I was told by a lot of people for ShopBot that it will work with only 1 vac.
I'm working on a new air camber for 4 2' x 4' zones with valves to run only 1 at a time.

[keebler303]

I suppose that depends on your parts. I run a 4x8 Shopbot PRT and a 10 HP vacuum is quite marginal at holding parts much smaller than 1'x1'.

If you can eliminate leaks so that you are only pulling on your workpiece, you might be ok. We found doing that is a huge pain when you are doing 1 or 2 of every part and the setup is always changing. Even with a zoned setup, you still need a spoil board on top of it and that will make the vacuum leak into other zones.

Make sure you report back if you get it to work, I'd be interested in seeing your setup.

Matt

[RCjunkie]

I cut a lot parts out of 1/8" luAnn ply and balsa

[keebler303]

If you are only cutting 1/8" you might get away with it. Thin material means your cutting forces will be lower so you need less vacuum. The other important parameter is the surface area of the part. Bigger parts will obviously be held better than smaller ones.

Matt

[RCjunkie]

Most of my cutting is with a 1/16"bit running at 14k

[ssutton]

I run a central vac motor on my 4' x 4' table. Ametek Lamb 115330 Vacuum Motor

The key to using this type of vacuum is large surface area and low cutting forces. I use my machine to cut sheet aluminum so I have no issues. Cutting wood can be a problem (even thinner wood) if it has any warp to it at all. If it is flat material then usually anything over 3 square ft of surface area and it holds down just fine. My table is divided into 2, 2' x 4' zones.

Scott

[aarongough]

How thick is the balsa you're cutting?

I experimented with a vacuum table for balsa at one point. The table was plenty strong enough to hold MDF and plastic in place, but the balsa was so porous that the air just went straight through it. I was able to easily lift/move the balsa on the table with the vacuum running, whereas less porous materials like MDF were held extremely well...

That being said the cutting forces involved when you're machining Balsa are pretty low, so if you get a vacuum pulling enough air it should be able to hold it in place. But I don't think you'll achieve that when your vacuum system is 'marginal' even with a perfect seal.