Hi. I’m using some thin wood which bows slightly. Any tips on how to fasten it onto the crumbtray to remove the bow while the laser does its job? Thanks.
Many of us use these.
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Thanks for that. I’ll cut some pins and see if that helps.
By using the pins for both lockdown and location you can repeat with multiple cuts as if it was a temporary jig.
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I also cut very thin wood in my GF. Holdown pins don’t work well for me because the wood sheets are often bowed in the middle where you can’t insert a pin. I use small neodymium magnets that I can place anywhere on the part. I’ve encased the magnets in steel on the top and side for shielding. This redirects the flow of the magnetic field downward so there is no interference with the head or air assist fan if they pass over one of the magnets.
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Most thin wood products will have a slight bow, I always sight down the edges to see it, place the crown down and pin the edges. That way you know the middle is down flat.
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The wood I use is 9"x12"x1/16". Pinning down the edges on either side most often won’t work because as soon as the high edges are pinned around the periphery, the bow in the wood pops up to the other side. Using the magnets, I can push down the middle anywhere I don’t have a cut path.
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Yes I learned my lesson with magnetic fields and have shielded magnets as well but very rarely need to use them once I started thinking from pins. Rotation is the biggest problem I find and by carefully putting the pins in the same row of holes I can get results like this…
of a three inch design cut from a 3-1/16" piece of wood.
Yeah, I’m pretty well hooked on my magnets. 
They’re quick and easy, and they keep the piece as flat as possible. That’s important because I’m cutting out a set of small mount holes that must be positioned precisely. A board with a little warp can throw the hole pattern off quite a bit.
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I guess I am surprised the wood functions adequately as a magnetic flux shield. I use hard drive magnets that have a metal shield.
I use pins for many materials, but when not appropriate, just use bare magnets. Worked fine for years.
https://www.amazon.com/gp/product/B072K5SLXK
The only issue is if they get onto the bed itself, I need to use a tool to pry them off.
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Wood? That’s powder-coated steel shielding the magnets.
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I started out using bare magnets. The magnetic field would interfere with the air assist fan and the laser wouldn’t cut all the way through when the head passed close to one of the magnets. The shielding alleviated that problem.
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That has been reported but I’ve never had an issue in 4 years.
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Before they enabled the air assist error I could stand behind my GF and watch the air assist fan physically stop as it hovered over a quarter sized rare earth magnet.
Now that the error is enabled I have to watch out for magnet placement because the error will blow the project.
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The only thing I can think of is perhaps they used a different fan early on, but I wasn’t one of the first. Dec 2017 here.
I made the pins as instructed in the first post and they seem to be doing the trick nicely - it’s only 2mm thick so holds down well.
I just intentionally ran a print with magnets positioned directly underneath the air assist fan (which I would never normally do).
I use pins on many materials but magnets work better on others - like cardboard, card-stock, chipboard…
I guess I’m just lucky.
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Can’t guess why. My Pro is even slightly older.
Have been pretty careful to keep the magnets away from above the area to be engraved since getting the errors early on. So haven’t had the error in a couple years. Don’t use the GF much anymore. Mostly for templates and bits to help with other projects.
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For the first year, I was using an array of different magnets and having all sorts of trouble with not cutting through, some were strong neo magnets, some were weaker fridge magnets, and some happened to be shielded though I had not been paying that much attention.
As would be expected the result was all over the place, and I figured out that if the fan stopped the smoke would make a candle flame but only later figured that was where it did not cut through. I was looking to some sort of crud slowing or stopping the fan and cleaned it regularly, never guessing the magnets were the source of the problem.
Only after the crud and a bad round with Novec killed the first, and I got a new machine and the magnets stopped it dead. Then I realized about what the magnets were doing.
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