Lazer burning the back side of the wood

Hello everyone My name is Justin Collins I am very new to Glowforge and I am having a small problem. I recently Have purchased some 3mm plywood that is NOT proof grade. I did some reading and found I need to get something to layer on top of the plywood. So I went on amazon a bought some Greenstar TransferRite Ultra 582U Medium Tack Transfer Tape to protect the wood. Well after a couple of cuts I am finding that it is not doing much. I am still getting burning and charing on the back of the pice and light burning on the front. This is with the transfer paper on the front and back of the pice! I am also make sure it is adheard well to the wood. So my question is, is there anything I can do to make this burning stop or should I just try another type of paper. Any suggestions are greatly appreciated!

You are cutting using fire, so there’s no way to eliminate it entirely BUT the burning on the back is called flashback - that happens when your cut is overpowered is hitting the grate under the wood and flashing back onto the wood. You can use the masking on the backside as well, but it sounds like you need to narrow in your settings better which should help on the front side as well.
This post from @evansd2 should help!

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You need to increase your cut speed.

The speed you’re using now has that red-hot laser beam lingering over each spot long enough to burn through the masking, burn through the wood, hit the metal crumb tray, reflect back up to the backside of the wood, burn through the masking on the back, and start burning the backside of the wood.

If you cut fast enough, the laser beam will have moved on before it’s burned through the masking and left any unwanted marks outside the cut line on the back.

The Proofgrade cut settings are already set at the right speed to do that on Proofgrade material, but when you use your own wood, you have to determine the right speed to use yourself.

You can discoer that optimal speed by doing some test cuts on a small piece of your new material. Start with the speed you’re using now, and cut a 1" circle or other small shape. Increase the speed by 5 and see if it still cuts through. If so, increase it by 5 and do another test. Keep going until you find a speed that is too fast to cut all the way through the wood, and whatever fastest speed you used before that test is the speed you want to keep.

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ok thank you so much dan I will give that a try!

Exactly what @dan84 said, here’s a method I use to test settings all in one go… check out #6:

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Hello @justintyler024

Since the question you have is about settings for non-Proofgrade materials, I will be moving the post to the Beyond the Manual section in order for the communication to continue.

If you run into any trouble with Proofgrade materials, please don’t hesitate to reach out and I’ll be happy to help!

Sorry about the topic being closed. It’s now open for discussion.

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