Fixture for Vacuum workholding and double-sided cuts

I designed and built this fixture as a fast, clean alternative to painters tape. It doubles as a jig for double-sided cuts. This video walks through testing and using it.

19 Likes

Nice,

What material did you machine the vac plate from?

Is that a single ring gasket or an adjustable length?

One of the problems with vacuum fixtures is the “leakage” in the areas outside of the gasket. This reduces the hold in the area inside of the gasket.

You could reduce this effect by making isolated channels in your fixture that only connect at the vacuum input.

You could add a vacuum manifold to make connecting to these multiple channels easier.

You could add a vacuum reservoir (tank) to hold the piece in case your air/vacuum goes down (power outage.)

We didn’t get to see the finished ash tray! :smiley:

Added: Never mind. I see you’ve already created a vid for the “cigar bowl.” Making a Cigar Bowl - From Design to Finish - YouTube

1 Like

Its gasket cord so you can layout any pattern you want as long as you mate the two ends to complete the loop. Basically a butt joint with a tiny overlap so the two ends push against each other to seal the gap.

3 Likes

I’ve used this for a couple months and had zero problems with leakage in any job or test I ran. If you’ve used a system with the problem you described, its either not machined correctly (channels have voids or ramps) or there’s you’re using a bad gasket material (wrong material, cracked gasket…take your pick).

What are you using for a vacuum pump?

Its a vacuum generator driven by compressed air (the device I’m holding in my had at minute 2:04 in the video). You could use a shopvac as well but this is way more convenient since I can switch on/off the vacuum at the fixture (see that at minute 3:00) it sips air so most of the running time, its running on the compressor reserve tank. The generator can run from as low as 30 psi air pressure and consumes around 0.735 CFM of air (so, very little air flow from the compressor).

I did a test just before recording this video, where I ran the vacuum fixture with a piece of stock attached, from 90 psi (max working pressure) all the way down to 30 psi (lowest reliable pressure I could get from the compressor). It worked throughout that process.

Its also simple to expand the machinable area by connecting multiple fixtures together. That’s one new feature I’ve already designed and will be machining today once I get some parts I’m waiting on.

Bonus, the vacuum generator frees up my shopvac for other duties (e.g. dust removal).

I haven’t watch the video yet, but really want to try this. I have several parts that I make regularly and have special jigs to hold/mount/locate each piece. Those would be a prime example of using a vacuum system instead of the tape method, as I machine 4-6 in a row of each part. Turning off the vacuum and exchanging the part is way more efficient then redoing the tape each time.

1 Like

Can we talk you into providing the file to cut the HDPE?

And maybe any specifics on the vacuum generator? I have a small vacuum pump used on my large, but my large air compressor is 3 feet from the CNC and may be pretty convenient to leverage.

1 Like

That’s exactly why I built this; to speed up production runs. Most of my parts are double-sided cuts as well so I solves that problem at the same time. Now I don’t need to redrill holes or fiddle with setting zero on an existing hole everytime I want to machine the second side. Zeroing on the dowel pins gives great accuracy for two-sided cuts.

I will be offering this for sale in a full kit (dowel pins, vacuum generator, hose, gasket); though the final version will be a different material. HDPE warps and dents easily so its great for a prototype but would not hold up over time. I also redesigned it to add a few features that make it easy to mount and expand.

Let me know if you’re interested.

1 Like

Sure, I am “interested”. I guess it depends on the price point though.

Consider offering a full kit and a DIY kit maybe to target different market segments.

1 Like

In addition to this fine example of a particular hold down fixture, one can search and find many alternatives from different materials. With some thought one could make one from almost any material. Search for “vacuum hold down fixture”.

e. g. How To Make Easy Vacuum Fixtures For CNC Machines | CNC Router - YouTube

2 Likes

I may be interested as well if the price is right.

1 Like

Could you add a link to the vacuum generator you are using?

What about when you cut through your work piece (+ a few thou)? Doesn’t that damage the gasket?

I’m working on a video to show how to do this. I’ll share it here as soon as its available.

Here you go: McMaster-Carr. Its about $43. Since recording the video, I tested with a much cheaper option that works equally well.

1 Like

That’s awesome! Thanks for the video.

1 Like

Thanks Adam. I have more coming plus I’ll be giving away a couple vacuum jigs to subscribers.