Vacuum Table Vacuum Equipment Suggestions

CNC Machines Shapeoko
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So I recently cut a bunch of stars out of a 9"x8" sheet of .25" plywood using hot glue for hold down. The issue I ran in to was that some of the parts didn’t have glue underneath and would pop out after being cut all the way through. Some of these had defects from bumping around on the cutter when they popped out.

This lead me to the conclusion that it might be worthwhile to have a small vacuum table setup allowing the parts to be held down until the vacuum is turned off. I have an idea of how to cut the vacuum table. My main question would be has anyone found a decent vacuum that is designed to run continuous for long periods of time? Possibly one that is significantly more quiet than a shop vac?

If there are any vacuum table plans out there that would be helpful as well, as it would save me the time of designing my one.

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The wiki has a section on this https://www.shapeoko.com/wiki/index.php/Workholding#Vacuum

which links to http://www.shapeoko.com/forum/viewtopic.php?f=30&t=7480&p=58845#p58845 and more.

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What I know about vacuum tables would fit on a postage stamp with room to spare.

BUT, once you through-cut small pieces, don’t you have the same problem you had w/ hot-melt glue? I’d think the vacuum would be broken and the pieces flying.

I’d consider investigating leaving what is called an onion skin (a very thin layer you can often break with your fingers and clean-up with sandpaper or some other tool), or tabs. And the best part is, you don’t need a vacuum to try it.

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I’m cutting 5 mm plywood with lots of small parts and several large parts in each panel. I’m using tabs but I’d like to incorporate a vacuum table because even clamped down on all edges a 17" wide piece of 5 mm ply raises in the center of the panel from the pull of the router bit cutting. I think if I used the onion skin (along with tabs because I can) with a vacuum table than I could eliminate this raising of the center of the panel. I’ll post any success I have. I had thought before about this but didn’t include the onion skin which maybe won’t break the vacuum pull and loss of vacuum effect since tabs along would ruin the vacuum pull. Thanks for musing about this, I have an a/c vacuum pump and think I could just pipe a shutoff switch into the line but need a large piece of thick rubber for the overall vacuum pad. Or peg board sealed and dotted with o rings on top of a thick panel with lots of narrow slots. Of course I could packing tape the whole waste board and spray glue the 5mm ply to the waste board to eliminate the raising of the center and tabs might be all okay without a vacuum enterprising complexity. Thanks for provoking my thoughts.

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I used to do a lot of veneering and I still have a veneer vacuum press. It’s basically a pump that draws the air out of a sealed bag and provides even clamping pressure. This, I guess, is the current version https://www.woodcraft.com/products/woodriver-vacuum-pump-kit . I’m just not sure it sucks enough for a vacuum clamp system, but it is designed to run continuously. My guess it’s the lower end of vacuums, which is probably about 1.5 CFM.

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Its not to difficult to make vacuum pucks for small work, but for your job I would use the masking tape and superglue method,

Apply a layer of masking tape to your plywood. Make sure tape is behind the small parts.
Apply a layer of masking tape to your wasteboard over where you would mount the job.
Apply wavy lines of superglue to the tape on the back o your plywood (or whatever)
Press the plywood to the masked area on your spoilboard.

You will not need tabs.to cut your pieces. When you are done just peel the tape from the spoilboard and the backs of your small pieces.

If you google around there are some youtubes illustrating this method. Set the DOC to the plywood thickness and the thickness of the tape will keep the tool off the spoilboard.

This method work well on woods and plastics. Would work on metal except for lube soaking the tape.

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If you’re going to go the superglue method, I’d suggest putting the superglue on the tape on top of your spoil board, and then wipe a thin later of baking soda on the tape on your workpiece. The baking soda will cause the superglue to kick-off very quickly.

The baking soda doesn’t have to be mixed with anything, works just fine to have a light dusting on the tape.

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I use the packing tape, spray glue (tack glue) and packing tape with scroll saw patterns and others. It’s worked great and easy to remove. Haven’t tried it for the cnc but will tomorrow. the packing tape is suppose to lubricate the scroll saw blade also. We’ll see but I like the tape protecting the waste board for thru cuts, I’m just scratching it now. I have a hdpe waste board so we’ll see how well if anything sticks to it though. Is there anything that you can’t use baking soda for, my son just detarnished a silver dish with it and aluminum foil. FYI , google Onondaga Lake in Syracuse N.Y., the most polluted lake in the country from the Arm and Hammer Baking Soda company over 100 yrs. of dumping their waste into it. Than they built a glass mall on the shore because it used to be so beautiful. Baking soda musings:.

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The super glue and tape method works well, but it’s a little tedious. As @cgallery suggests, using a kicker is helpful. I use a spray, but baking soda works great. I recently bought some Nitto fixturing tape, but I haven’t had a chance to try it yet. It’s expensive, so I hope it lasts a while.

I doubt that most vacuum pumps have enough volume to maintain vacuum after the workpiece is cut through. I think a higher volume shopvac would do better, but still might lose suction when the total area of the cut-through kerf gets too high. Onion skinning in combination with a vacuum table might work really well. I wouldn’t worry about running the shopvac for long periods. If your router can handle it, so can the shopvac.

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Thank you for the tips and suggestions.

If I were to create a vacuum table with a grid of holes and lined the center of each part with one of the holes would that work with through cuts? I would assume the vacuum would still be pulling on the part regardless if it was cut all the way through.

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There was a vacuum table plan from C3D, another option for you to o consider would be to leave an ‘onion skin’ on the bottom by leaving a few thousandths of an inch and using a utility knife to separate. That would prevent cutting into the vacuum table surface.

One thing to consider is the surface of the plywood may not be flat enough to get a good grip. Depending upon how large your parts are, you may want to consider placing a gasket around your vacuum holes under your parts, which would effectively make small cups specific to your requirements.

Making one is still on my todo list, just haven’t had time.

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In my experience, this is true. I have expiramented with vacuum tables a little. (Really… just a little, so take this with a grain of salt.) I built a couple of small (8.5" x 11") vacuum tables with both a small 12v vacuum pump from Amazon, and (alternately) using my shop vac. The shop vac version maintains pretty good hold even with a little air leaking once parts are cut through. It does start losing grip as the cut-through surface area expands, but it does a better job than you would think at holding even when a lot of air is leaking.

You can actually hear the tone of the shop vac change as this happens. To see what I mean, just hold your hand over the end of your shop vac to stop the flow of air… the tone will change. Now remove your hand and you’ll hear it go back to normal. The same thing happens as your work piece is cut and more air leaks. If you do this a lot, you get to the point where you can hear when the table is losing holding power and is about to slip.

How much holding power it has vs how much you need depends a lot of the design of what you’re cutting, how thick your depth of cut per pass is, (how much lateral force you put on the work-piece with the end mill), and how much air leaks once it is cut through all the way around your piece. Having a higher friction vacuum table surface helps also. My vacuum tables are HDPE, and they’re very slippery. I think resurfaced MDF might be more slip-resistant.

I originally planned to cut only 8.5x11" work pieces, and so I pocketed a 8.5x11" recess that is .03125 deep for the piece to set down in. That prevents sliding when I am using a blank that fits perfectly, but prevents me from using it for anything larger.

Using a smaller end mill for cut out helps noticably (reducing air leakage). If you’re cutting something thin (<1/4"), using a drag knife can perform the cutout with very little air leak and loss of holding power, but even switching to an 1/8" end mill from a 1/4" end mill has worked for me in some cases. (Cutting paper with a drag knife was my original use-case… this worked mediocre, and I’ve ended up using the vacuum table more for wood than paper.)

It’s worth pointing out that because I only have one shop vac, I have to choose between using my dust collection or my vacuum table.

Bottom-line: for your use-case I think there is a very good chance that a shop-vac powered table will work great. The little $20 12V pump I have doesn’t have the CFM to maintain holding power when the piece is cut through, so if you go that route, look for something with better performance.

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I’ve got Sea Monkeys growing in something like that :slight_smile:
They’ve been living in the same 1 gallon tank for 5 years.

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Not really, the sludge is green and so thick that the scientist type divers have to be roped to the boat cuz they get vertigo from not being able to see up or down. One plan to rescue it was to air dump 6 inches of dirt over the entire lake bottom to settle the sludge to the bottom, but that didn’t get accepted. Sea monkeys won’t live in this stuff.

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I use this tape, it’s pretty thin and has (for me) the right amount of ‘stick’ to it. Comes off the piece but it’s almost never let go of a piece, even with minimal tape. With my machine flattened waste board I can cut right to the tape without going through the tape if I measure and zero carefully.

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havnt seen or heard of sea monkeys since i was little,thanks for the trip down memory lane :wink:

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You might take a look at this post:

It’s for a Nomad, but I think many of the principles probably apply.

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