When laser cut is not through and through

I cut 1/8 inch birchwood. Some places cut only partly. Are there any tips on how to clean cut these sections?

Do you have air assist? How much pressure?

Sometimes I run into that problem and it’s usually that run of ply has different adhesives.

If you’re cutting natural products it will still vary.

Air assist, would help, but the other option is slow down or increase the heat.


What are the specs of your machine? Is it a co2 laser or a a diode laser? What is the power output potential? Do you have good fume extraction to clear smoke? Do you have good air assist to clear cut? The more information that is provided, the better the responses will be.

Thanks @jkwilborn and @Stroonzo for your feedback. I do not have my own machine. I got these cut at our library and plan to go there and cut with slower speed. Wanted to update you on status. No further help is needed.

I post on this issue all the time on supposed baltic birch. More than likely you hit voids in the inner laminate that have filled with glue and you won’t burn through them easily as the glue just melts than fills back in. Easy way to tell is to look at the spots where it failed to burn through. Voids will be all dark and full of soot from the burning glue and if you look at the inner laminate where it failed to burn you will see the void filled with glue. Also as it cuts through you will see the laser flare up as it hits a glue patch and even on the top surface you will see small black soot spots.
Fix is to find better birch.

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Thanks @shughey - This is what I used https://www.amazon.com/gp/product/B07CHX1GTD/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

laser cut

I used 100% power, 60% speed and 2 cuts

if you look back in the reviews you will see people having similar issues…its glue voids…its always glue voids…any 40 watt and up co2 can cut through 1/8" birch in a few passes UNLESS you hit glue filled voids. Baltic Birch used to be great but the russians have pooped right out making it now.

see those partially cut circles in your pic…gauranteed the uncut section has voids with glue…you can snap them out and see the pockets of glue…typical.
I don’t use high power I will go maybe 50-60 percent at 20mm sec and several passes to keep the soot mess down.
I did find some good 1/8 on Etsy believe it or not…I think it was from Glowforge but not sure. You have to try a couple sources and find one with minimal voids. SOme are so bad you waste every cut…others are way better and only run into a void now and then

Thanks @shughey, Another possibility I am considering is Delrin. Instead of birch, would Delrin cut better as there will be no layers and no glue? I am making a personal hobby robot and weight is important. Would similar considerations (lower power percent and multiple passes) also be appropriate for Delrin?

I have not personally cut Delrin on my laser although I very familiar with it in making prototypes. My guess would be way better the only issue is what is delrins chemical makeup and is toxic when making fumes. But it would cut nice,
So…make a new post and ask about cutting Delrin and I am sure you will get a quick answer.

Why not like an opaque black acrylic sheet. We know that’s safe to cut…fairly strong certainly and easy to cut. I find eBay has good deals from sellers…better than Amazon usually. Jpplus has it for 9 bucks for a 12x24 piece or half sheet is 17… they shipping. I see eBay has a half sheet for 31 bucks shipped that’s not too bad and no waste like birch.

Can laser cutting be used with HDPE? @shughey

I do not cut any of the plastics other than acrylic based items so no idea on HDPE…google it…laser cutting HDPE and see…I am sure there will be many hits…google is your friend

I will look for a PDF I have that lists what you can safely cut and engrave.

To put it in a nut shell, only natural products, wood, paper, leather, slate and acrylic or it’s cousin polycarbonate. I think it’s what they made our shields out of…

You can find where people cut vinyl records and the machine had to be scrapped :frowning:

It could have been worse, as the PVC type materials produce, along with other gases, chlorine.

Know what you’re dealing with…


Thanks. I look forward for the pdf. I came across jpplus.com that sell laserable products.

Here is a DO NOT use list:

And here is a “safe list” pdf via a google search:

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