Not cutting PG wood, even at slower speed

So it seems my laser has lost a lot of strength, particularly after the latest software update. It’s been a long time since I’ve been able to cut PG wood using the default settings. To compensate, I’ve been going with default settings with -10 speed… and more recently I’ve downgraded to -20 speed since the update since the PG Medium Maple Plywood I typically use wasn’t getting clean (or sometimes ANY) cuts, even at -10 speed.

Just now, I tried to cut medium draft board with -20 speed (148) from auto settings for cuts… It didn’t cut all the way through and I had to scrap the whole board.

Does my laser need replacing? The lens isn’t dirty or anything…

There may be a few things going on here

  1. There are 5 places that need regular cleaning; the lens is 1, there are also 2 mirrors, 2 spots on the bottom of the head, and the camera (instructions here)

  2. Check the thickness of your PG. There have been reports of thicker PG - and if you’re in an area with any humidity that can also swell the wood

  3. Every time you finish a job you should pull out the pieces without moving your base board - that way if they didn’t cut all the way through you just need to close the lid and run the cuts again

So - give the rest of your machine a good cleaning, and measure your PG. Between the two I bet you’ll find your culprit - and unless you’ve put more than 10k+ hours on your laser already it doesn’t need replacing, just cleaning!


Ha, cleaning the mirror is a step I forgot! First test seems to show it working correctly now… Time for the big test. Thanks!


I’m so sorry to hear that you ran into trouble.

I see that @deirdrebeth provided some great first steps for items to address when cleaning, and you are already experiencing better results after following some of the tips. Thats great!

Could you please let me know if you’re experiencing the same snag?

It looks like a smudged mirror was the culprit! It’s cutting like a dream now. =) Thanks, @deirdrebeth!


Also good to verify the lens is in the correct way–I once had a big drop in cutting, and turned out I put the lens back in upside down!

I’m glad to hear that cleaning the mirror led to your Glowforge cutting as expected! I’m going to close this thread. If you run into trouble again, or have any questions, please post a new topic here on the forum or email us at and we’ll be happy to help.