How to prevent char on the back of thick wood

Hi, I am cutting on some .483" thick pine. I have been trying all kinds of settings but I cannot seem to figure out how to get rye back from charing. I am using transfer tape on the top and rear which is very similar to proof grade material. The last settings I used which got me close was 6 passes with 300/full.
I have attached 2 photos of the front and back for reference.

Thank you in advance for you thoughts and help.


A wasteboard would probably do it. Keep in mind that masking isn’t the toughest stuff, it’ll protect against just a tiny bit of extra laser energy, your final cut is pushing too much pastbthat limit.

A piece of thin plywood would probably absorb the energy that is making it through. You have about 1/8” of play in your height, as the laser can focus up to .5”, so a piece of cheap 1/8” ply would just fit.

Just remember that 1/8” ply isn’t quite 0.125 in most cases, you’ll want to measure everything carefully to get your new adjusted height. Good luck!

There’s also a slightly elevated risk of fire with layered materials, but that really only applies to thin stuff like papers. I’ve successfully cut with a ply waste board and there was no flashback at all.


Following @takitus’s advice, I’ve also taken to putting a layer of painters tape over the tray to help reduce flashback from the grill.


Awesome, I will try this today and let you know the results. :slight_smile:

I hope your print went well! With regards to printing on materials provided by other vendors, unfortunately, I don’t have any guidance. I’m moving this to Beyond the Manual so the discussion can continue there. Note however that advice in this section is unsupported and is not reviewed by Glowforge.

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