Vacuum Table

[CNCRob]

Over the past few months I have been working on a new vacuum table to hold some of my work in place. I have been through a lot of trial and error and have come a long way, but still have a long way to go. I have been reading just about everything I could find about vacuum systems and homemade vacuum tables. So I thought I would start a new thread to share some ideals and gain ideals from others. I am going to go through the photos that I have taken of my table so far and post a few of them and my experiences I have had been through so far on my quest to make a vacuum table. Feel free to weight in and share any ideals you may have. Also if you have a homemade vacuum system please share it with us, I would love to see how others tackle some of the challenges in making a vacuum system.

[kdoney]

I'd be interested. I've made a couple. One worked but it is just some pvc connected to particleboard with plumbing fixtures. All on or all off.

[Zippi]

I'm working on a vac-table, suction area will be about 36 sq in, it will be made from a 1" thick slab of 6061, ~5" x ~15". I'm planning to use some 1/4" EPDM foam cord for the seal, and will be dealing with non-porous surfaces.

One of the "unknowns" for me is determining the depth of the channel that the EPDM cord will sit in. If I remember right, it will compress 25% at ~10 PSI. The cord's diameter tolerance isn't great, so just using a 75% of .250" slot for the seal may not work. I'll test the channel depth on a piece of scrap before I mill the "big slab".

I built a venturi vac (thread in this forum), and am building a second one for a "how to" for this forum (got pictures of construction this time)- I'll finish that up when I get around to it...

I bought a vac-clamp (from www.vac-clamp.com). My design is losely based on the vac-clamp product, in aluminum. No grid structure for resizing of the seal as in the vac-clamp, I'll be dealing with the same size plate every time.

I'll gate the air to the venturi vac with a solenoid-actuated valve.

I've seen pressure switches, but haven't yet looked for economical "vacuum switches", something to tell me when the vacuum level is appropriate (a "yes" when the piece is properly sucked down). Initial thought is to take a vacuum gauge, rip off the front of it, and wire in an optical sensor pair to read the needle position. It'd be cheap, and somewhat adjustable, too!

[ger21]

I used this switch when I built mine. I managed to find a different source, and got it for about $15, but I don't remember where. http://www.joewoodworker.com/catalog...products_id=58

[2muchstuff]

Square D makes vacuum switches. Like pressure switches on an air compressor but in reverse.

[Zippi]

Thanks, Guys!

I had a "duh" moment- how else would one know to shut off a vacuum?

I checked the 1" alu slab, very true.

The 1" alu slab has a brushed finish, which I think will be advantageous as a vac-table. I'll cut "veins" into the table top within the gasketed area, I suppose you could call the brushed finish "capillaries".

No new work on this table as yet...

Thanks,
Paul

[Cold Fusion]

Any pictures?

[Zippi]

No pics as yet... I picked up an Asco 4-way valve (120v AC) and a Whitman vacuum switch off Ebay, arrived the other day. I had to loosen the switch and move it a hair to get the switch to actuate on a vacuum. I need to test the coil on the valve, but I'll probably be driving it with a Sharp S101S02 solid state relay (good for 1.5A at 125v AC, the solenoid is only 17 watts). I wonder how these SSR's will handle this solenoid...

[Ed_R]

I think vacuum tables are the way to go. I just don't know enough about them to build one yet.

[CNCRob]

Im glad to see all the interest, maybe together we can come up with some pretty good ideals.
I have some pics I will try to post when I get the image size changed.

[Geof]

I am in the process of outfitting a large machine with a vacuum table. Actually what I will be doing is 'tiling' a 5' by 10' surface with eighteen separate vacuum surfaces each 19" by 19". So far I have not progressed any further than a model of the vacuum tiles shown upside down in the picture. The four corner holes match up with an existing 4" by 4" array of holes tapped in the machine table and the tile will be bolted down with an O-ring gasket around the perimeter so the machine table forms the bottom of the vacuum cavity. Two indents can be seen where the perimeter wall loops in and this is where venturi vacuum generators will be fitted. Each tile will have its own controlled air supply. The aim is to install these tiles on the table, face and machine the top surface grooves for gaskets with full vacuum applied so that in use the surface is as true as possible and mark each tile with its location. It will then be possible to remove the tiles for non-vacuum work and replace them in the same location and go back to the same accuracy. My goal is flat to plus/minus 0.002" over the whole surface for engraving on large areas of thin material.

[ALpmc]

I'm normally a reader and not a poster but I do have a little experience with home made vacuum tables that I don't mind sharing. I'm not exactly sure where I saw the original design that mine is fashioned from but it seems to work really well! It's made from 1 inch 6061. It's base is 6" x 3.5". It's working surface is 5" x 3.5". It has 9 horizontal (Y) channels and 9 Vertical (X) channels. Each channel is 1/8 x 1/8 with chamfered edges. The gasket material is 1/8 x 5/32 leaving 1/32 above table level. There is a single 1/8 hole in the center of the table that provides vacuum to all channels. I don't have any details about the vacuum pressures. I just use a small vac/compressor without any problems. I use it for small engraving jobs or when I need to fly cut several pieces of stock when I work on multiple projects of the same piece.

This link will show you a page with one Quicktime movie at the top showing my first design in action. Click on the photo and see a page showing 8 short Quicktime movies of how I made the vacuum table. Click Here