Not cutting right

So I am still really new to this so be patient with me. I have been cutting several of the same item for some orders I have. On some of my plywood everything comes out great. But on two different pieces things took a turn for the worse. My cut is no longer cutting right. It cuts through, but I have to force apart the pieces that are cut away. And instead of having that nice fresh cut smell it smells like a dirty old ashtray. I thought maybe my speed was a little high so I slowed it down a bit. Didn’t help. The plywood doesn’t look to be bad in an way. It’s the same species from the same manufacturer. I am using the same file and settings. I had a small piece left from the other board so I tried it out and it is cutting fine still. What am I missing?

Sounds like you’re not using Proofgrade or another brand of plywood specifically meant for laser cutting? Other plywoods can have glues, fillers or other inconsistencies that can make for a rough laser experience.

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It came from Smokey hills design.

You state that a piece left from a previous board was fine, so I’m thinking it is the material. Wood is a variable, natural item with some glue and filler thrown in for good measure in plywood. You may have to adjust your speed/power.

When things don’t cut as planned, or as they have in the past, perform the basics. Clean all optics - including the side window. Clean all the fans - exhaust, printhead and air assist, make sure the material is pinned absolutely flat. Use the set focus tool. Make sure the honeycomb tray is properly seated. Make a small, test cut before doing your entire project.

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I’d suggest you ask them about your specific material then. It might be an issue they’ve either seen before or would want to be aware of, definitely sounds like an aberrant material and not a machine settings case.

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It is very easy to fog a window that passes the laser beam that will make the power only slightly less but enough to make it not cut through. As well even if the filler can be cut it will take a bit more to cut it and it is likely to smell very different.
Looking at the side of the cut will spell out the story.

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If you’re working with materials from other sources, you need to test first to find the settings that work for it, and then still be prepared for inconsistencies, even across the same sheet as you can get different results. This is part of why Proofgrade is more expensive - it’s amazingly consistent. Even quality ply from higher-end woodworking stores is not as consistent. I buy Baltic Birch from Rockler. It’s good, but not Proofgrade good.

Some of the worst I’ve used is Lauan-branded underlayment, but it’s so cheap, I accept the issues and have used it for a lot of prototypes and larger projects. “PureBond” ply from Home Depot is really nice, and also cheap, it’s just not finished or masked. I have never had a problem cutting it with the saved settings I initially settled on.

Proofgrade material just works, every time, 4 years in. I have a stack over a foot tall.

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when was the last time you cleaned all the lenses and mirrors?

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I haven’t even had the machine a week yet. I did clean it yesterday as I want this thing to last a long time.

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dirt on the lenses isn’t necessarily a “date” thing as much as a “how much dirty stuff have you been cutting” thing. if you’ve been cutting a lot of plywood, MDF/proofgrade, or acrylic in those couple of weeks, you could get something on a lens/mirror. if my GF stops cutting through efficiently, that’s probably #2 or #3 in my list to check (behind making sure material/crumb tray are flat and that i really did have settings the same).

at work (different laster), we tell everyone to at least wipe everything down at the end of the day if they cut. not necessarily lenses, but all rails, etc. i’m not that good with it at home on the GF, but checking the lenses and mirrors regularly to make sure they’re clean is good practice. and wipe down the camera lens while you’re doing the others.

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A single long cut can fog the lenses enough to change the depth of cut. You want to have the proper Zeiss-type lens wipes. The window on the side of the head and its matching one hiding under the left side (that many folk miss) are usually the first to fog and thus need the most attention. It is amazing how little fogging it takes to have a big effect.