Vacuum tray replacement for cutting lightweight materials

Yeah I didn’t try the gap between the lid and the door, I went around the side between lower door and frame. It worked out.

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I’m a bit surprised to have not yet seen any jokes about how this appears to really suck. :wink: So I guess this makes me the first?

The only thing that could make this better is a parts list with links. :grinning_face_with_smiling_eyes:

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Aluminum foil lining. Glue, staples, or wedge it in with a couple of furring strips

Did you use 1 fan or 2?

Edit: I see the answer 2 posts down:

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Congratulationsn @evansd2, I love how creativity feeds this forum. Thanks for your idea!

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Well that’s the trippy part about pressure differentials, you don’t need much.

Let’s say this is pulling only 1 psi static pressure. With a 5"x5" square of material, that’s a total of 25 lbs of downforce. Even if that estimate is really high, even a fifth of that is like a 5 pound downforce.

It adds up really quickly. Now the CFM angle comes in because as you cut the material you’re opening gaps and eventually all your kerf becomes a notable “leak” in your seal. A high CFM fan is required to keep pulling air through those gaps while still maintaining a pressure differential. A fan with a really high static pressure* and low cfm wouldn’t be enough, a fan with really high CFM and very low static pressure is much more viable than the other way around.

In any case, this little guy seems to be doing the job, so I’m pleased. I’ll probably add the second fan just to try it out, it’s already in my amazon cart. :slight_smile:

* A high static pressure is actually a problem in its own way. You need to have a screen surface that can withstand the downward force, something with a high open % (meaning more air than material surface area) and very rigid like the current crumb tray would be great, but steel honeycombs are hard to source and hard to work with. The nice thing about the mesh is that it cuts to shape easily with tin snips. It won’t withstand a lot of pressure without deflecting (bending), so we’ll see if the two fans cause a problem. I suspect they won’t, it’s been a long time since my fluid dynamics courses but I suspect this will increase total airflow a fair amount but static pressure will not increase much at all. Physics!

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A 40 mm fan is ideal here, you can use the fan specced for the air assist (~19$):

Or if you want to save a few bucks and get marginally lower airflow, you can use the one I have (~13$):

EDIT: jump ahead to this to see discussion of higher power fans:

The screen I chose was this guy:

I liked it because it was a bit heavier duty than many others, I wanted it to be fairly strong.

It comes rolled up, so the first thing you have to do is flatten it, which requires bending it back the other way. I actually rolled it “the wrong way” around my masking material roll, it was the perfect diameter to bend it back to flat. Wear gloves when handling the screen mesh, the ends are pointy.

The rest was MDF and a 12v power supply I had laying around, and a few electronics bits I had laying around (switch, vero board, pin headers, wires, solder, assorted screws and other hardware you want to use etc)… but most of this stuff is up to you. The fan and mesh are the only really bespoke things I purchased for the project.

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Sorry for the spam but I’m still figuring out what this is good for.

So I cut some linen fabric. The tricky part is that the fabric is (of course) porous and can’t get a good seal.

I laid some trace paper on top of the fabric and made a linen sandwich. It worked pretty well.

I’d probably be better off masking the fabric, the masking would stick to the linen and would not rely on the vacuum to hold the sandwich together.

It worked but I probably wouldn’t do it this way with something as light as tracing paper again. Maybe cardstock. More experimentation needed.

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Great minds! aluminum foil high five

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Darn. I missed that in your earlier reply.

I’ll take the high five anyway.

I think you might have inspired me to do this. I’m taking 2 weeks off to end the year I’ve still got bits of paper floating in the machine from last time I cut paper.

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I was thinking aluminum flashing. Foil might melt, flashing would not. Might make the the whole bottom and two sides in flashing if I can get the bending right.

I am thinking 4" fan pointing up

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I considered this. It could work for sure. I’m not sure you’ll get more static pressure but you can definitely get higher cfm.

There’s a breakpoint in terms of how large the fan can be versus how thick your box can be, otherwise you’ll see diminishing returns as the air is impinged.

Good example, almost the same power draw but 5x the airflow. It’s 38mm thick, which leaves you at most a 0.5” gap to stay under 2” total height. I’m definitely not saying it can’t work but that was the sort of restriction that led me to abandon it and go for a 40mm solution. I wanted the fan to be enclosed in the vacuum table. You could theoretically fit a 50mm fan mounted horizontally but I didn’t want to bump up to the physical limits like that, so 40mm is where I landed.

As for flashing… I think heavy duty kitchen foil is plenty to stop the excess laser, and easily replaced if need be. Much easier to work with than flashing.

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Not strong enough for structure but you already have that. It is very soft and easy to bend Only hard corners might be tough. I also have flashing already :grin:

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What a cool idea! I love paper … and awesome ideas!

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This is tremendous. I’m always having paper escape during cuts. Brilliant.

Also I’d love to see some paper projects!

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thanks

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your results are amazing!

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This is awesome! Wish I had the skills to make one myself.

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WHAT IS THE WIZARDRY AND HOW DID I MISS THIS!!! Pretty friggin epic my friend!

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Got mylar? I would love to know if the little cut bits on a detailed design would stay down while cutting with that gadget of yours. I could send you some…

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Another incredible example of what is possible if it can be imagined - bravo :clap:t4:

I’m sure you’ve considered this, since you’re a rather critical thinker, but what’s to stop you from having your power/fan box being attachable and detachable to vacuum boxes of different sizes? I suppose it’s easier to have jigs to cover the excess areas, and definitely would save space and money, so there’s that…but having it be modular would be pretty neat.

Your design also has the benefit of elimating any sort of bow that paper gets when placed on the regular crumb tray. I make all of my earring holders in my machine, and occasionally the small fraction of focus height difference will cause the engraved areas to be lighter or not as sharp, due to my laziness of only using magnets to stop the cardstock from moving. I also rarely deal with flyaways as I very slightly under power the cuts so they can be perforated and pop out fairly easily.

This is a project that I would love to make, but as I mentioned, my laziness will impede me from ever taking it on, though your examples are absolutely tempting :sweat_smile:

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