Another Vacuum tray

Building on the great vacuum table design that evansd2 created ( Vacuum tray replacement for cutting lightweight materials ), I took a swing at it with a slightly different approach.

I used almost the same fan he recommended, purchased from DigiKey: 603-GFB0412ES-E-ND, and the same SS screen that evansd2 sourced from Amazon (see his great write-up and links)

I decided to try an open bottom version of the vacuum box, that uses the SS plate under the tray as the beam stop. The open bottom design is easy to clean, and the plate stops the laser without any marks or discoloration after use. The vacuum table just rests on the SS plate with weather stripping around the bottom perimeter to make an airtight seal and keep the table from sliding around

I also wanted the SS screen flush with the tray top so that I could use paper bigger than the tray and it would lay flat. This is also convenient for masking open areas on the screen by just laying sheets of paper around the perimeter of smaller work pieces without the need to fit into the “well” of the screen area. However I don’t recommend the method I used to achieve this. I forced the screen into the hole in the top of the tray by pounding an inner ring into place (see pix) It worked, but it was a pain and the walnut cracked in a few places due to the stress. I am sure someone here will figure out a better way…

The frame is hardwood walnut, cut with the laser and glued together with Titebond III wood glue, and is very strong.

I built a cowling for the fan in CAD and 3D printed the part. It worked well, but beware that this fan doesn’t have enough head clearance for the bolts behind it’s mounting flange for some reason. I melted threaded inserts into the cowling for mounting to the fan and frame.

This fan has a PWM speed control capability built in, and so I used an Arduino UNO (the UNO can run on 12vdc) to create a signal that would regulate the speed of the fan. I used a pot (the knob) to control the desired PWM. I was able to pass the cable from the motor through the front pass through slot of the Glowforge by loosening the two thumb screws, removing the cover plate, and then re-installing the plate loosely on one side. Having the fan control outside the Glowforge was convenient, and I could adjust the fan speed during a cut as needed.

Initial testing created lots of vacuum, and beautifully detailed cuts on vellum. All cut-outs stayed in place without blowing around. it worked well, even at lower fan speeds, so such a powerful fan might not be needed.

At full speed, I started to see the screen bend inward (with paper covering it) and then start oscillating up and down! I ended up adding a piece of angle aluminum under the screen to support it and stop the oscillations. Only the very edge of the angle touched the screen so I still had good vacuum everywhere. Any laser beam reflections were directed to the sides from the aluminum.

That’s about it. You can see more in the pix. I am happy to go into more detail if folks have questions.

Cheers,

Matt










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Ooh that flush screen is classy. Nice.

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Quite a nice design! Thanks for the write up.

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I should say so! Your fan is 6x as much static pressure as mine. That’s beefy!

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Very pretty! And great write up!

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Yea, she whines a little when I crank her up… Actually the extra noise inside the Glowforge is almost unnoticeable compared to the exhaust fan. I will make a demo video when I get a chance.

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Success! Well done!

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Looks awesome

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Taking gf to the next level! Nice!

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Nicely done! Looks like a solid, effective design. I was also inspired back when @evansd2 posted his project and similarly wanted a flat top for passthrough use.

My design uses little foil-covered spikes to support the screen and a magnetic frame to hold it in place. My youngest daughter uses it more often than I do, but it’s still in use two years later.

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I imagine there would be interest in this. Have you thought about pricing and making more for other people? (not me, just curious is all).

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I do really like how you got that screen flat. I ran into issues getting power to the fan and the whole thing sits unfinished. I have a 4" diameter x one inch fan that I expect to move a lot of air and live behind the gantry but will have to rethink it from scratch now. But there is little current need so it will hold till the need is there.

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Interesting question. Watching for answer.

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This is a great post thanks. Inspirational

Very clean and looks great! Jealous!

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Thanks for all the great feedback.

I don’t think it would be cost effective for me (or the purchaser) to produce vacuum tables for sale, but I am thinking about a simplified design folks could make themselves. Perhaps a bass wood frame with the screen staple gunned to the frame top, and a single speed small fan at the back.

If I get around to sketching one up, I will post it.

Meanwhile I did a fly-away test using the worst case material–tissue paper! It worked perfectly (see video). Perfect tissue paper flowers, anyone?

Matt

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BTW, has anyone used this stock image service that offers vector art for laser cutting? Looks extensive and high quality, but pricey: Laser Cut Paper Patterns Stock Images & Video - Dreamstime

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I visited the website. Very pretty - but I agree they are pricey.

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I used them in a prior job for"regular" stock photography to create websites and such. They’re pricing is on par with Adobe, iStock, etc, but higher than sites that cater to vector files.

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They have a FREE section with pages of design. I also get a freebie from them from time to time, so I must have opened an account sometime back there.
Here is the free “pattern” list.
https://www.dreamstime.com/free-photos-images/pattern.html

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