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Author Topic: Your idea for a good Vacuum table (with Plexyglass)  (Read 3645 times)

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Your idea for a good Vacuum table (with Plexyglass)
« on: August 02, 2009, 06:28:57 PM »
Hi,

I have 2 sheets of 1/2 inch Plexiglas, 36 X 36 inches.

I would like to build a vacuum table for my CNC router.

How would you built it, would you use both sheets one over the other with spacers between and hook up vacuum hose between too.

Would you build 2 or only 1 ( 2, I could place both on the table if I have bigger board to machine)

Which is better, equally spaced holes, (if yes, what diameter should they be drill) or machined slot and put rubber material to be equal to the dimension of the board I want to machine.l

Would like to get your ideas because I would not like to scrap my material.

Hope to receive some good advice,

Thanks, Jeff



Re: Your idea for a good Vacuum table (with Plexyglass)
« Reply #1 on: August 02, 2009, 11:48:40 PM »
What are you cutting/trying to hold down with your vacuum table?

Sid
Re: Your idea for a good Vacuum table (with Plexyglass)
« Reply #2 on: August 03, 2009, 12:18:22 AM »
Hi, everything I can, PC board, wood, veneer, MDF.

Jeff

Offline simpson36

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Re: Your idea for a good Vacuum table (with Plexyglass)
« Reply #3 on: August 04, 2009, 08:43:49 AM »
Unless someone comes up with a specific suggestion for hole spacing and size, you might consider using peg board to build a proof of concept prototype before you spend valuable time and cut up your expensive material.

The 'table' will undoubtedly be supported around the edges and applying a vacuum will tend to bow the center down. My suggestion on the Plex table would be to use the second sheet to make reinforcing ribs to glue to the underside of the 'table sheet' and make the box from wood or sheet metal.

An alternative would be aluminum bars running every 6 or 8 inches or so under the plex to support it.

This should be an interesting thread to follow.

Offline RICH

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Re: Your idea for a good Vacuum table (with Plexyglass)
« Reply #4 on: August 04, 2009, 05:12:58 PM »
Budman posted his vacuum table he created in the Show  & Tell and you should take a look at it.

Assuming there is no leakage  ( positive atmospheric pressure ) in holding the part, say you had a single 1" diameter hole with full vacuum pulling the part down.
Area of 1" dia is .785 sq in. If your pulling 14psi which is  1 ATMOS ( approx ) full vacuum then you would be pulling the part down .785 x 14 = 11# of force. Holes and spacing are based on what you want to hold. Vacuum holes not used are covered ( unless you have one heck of a vac pump ). You can port to open or close a grid below the top plate. Porting can be sized based on the vac pump capabilities.

BTW a good analogy would be like comparing a vac table  to a magnetic base where one has fine poles or wide pole spacing.

That's the jest of it,
RICH
Re: Your idea for a good Vacuum table (with Plexyglass)
« Reply #5 on: August 04, 2009, 06:09:02 PM »
Thanks for the reply, would something like it would be more suitable, I've seen some model like it on the web.

Just did a quick drawing with SolidWorks.