Any Tarkin tips for thick materials?

Wild! I’m forced to conclude that the plywood I have is denser or has some sort of glue that is different than the one you’re using. It definitely wasn’t just struggling with the occasional knot-- it was failing to cut (ever) and glowing orange after the attempt. I’ll leave a piece tomorrow in case anyone wants to fiddle with it.

Heyo! I left some of that Fine Lumber 3/4" Baltic Birch by the computer (not the Tarkin computer, the other one). I might run some tests this evening to see if I can make any more progress. I’ll be in Tues/Wed/Thu during the day if you want to hunt me up.

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Curiously, after getting success straight out of the box on 18mm Baltic birch in the scrap bin, @Tony-Wright came by with HIS 18mm Baltic birch sample which did NOT cut. In any way. It not only won’t make it through at the known settings, it starts catching fire inside the cut early on.

This is odd, Baltic birch is known for its standardization. AFAIK the Russian govt is the only producer under that name and the only one using the 1.5mm hardwood laminations.

These are the two samples, and they’ve both got the signature 1.5mm plies of exact thickness, so I think it’s still Baltic birch. But the one on the LEFT, that’s the one DOES NOT laser cut. Note it has a very thin, dark line between each ply. I don’t know what the difference would be- BB does come in 3 grades but that’s about allowable defects like knots. I haven’t heard of like an outdoor grade with a different glue. This didn’t fail to cut because it hit a knot, structurally it’s different. And I’m not saying it’s inferior quality, it might be stronger or more weather resistant, it just doesn’t laser, a criteria that probably no one else on Earth would think could apply to it anyways.

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Pretty wild. if the dark lines are part of the reason it won’t cut, could it be some sort of fire-resistant safety measure. Just a WAG on my part.

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^^^^ Strong guess.

Are the dark lines actively fire-resistant, or are they just messing with laser absorbtion because they’re dark?

That is super interesting! (Also did not know that about BB==Russian govt produced)

I really appreciate this side by side picture! We should be sure to add it to the wiki with this info. Very important to know and look for when purchasing this stuff!

@Tony-Wright where did you buy this “different” unlaserable BB from again?

I was looking at Google’s images of BB and none have the thin dark lines of this material. We know Russia’s BB industry is troubled by supply chain issues in the last few months, I wonder if they’ve made a very recent structual change to adapt to the situation. If this is actually RBB, this does not bode well for the laser cutting crowd, because if so this would likely be a change that will soon filter into all the 3mm and 6mm RBB we more commonly laser as well, and while I expect it will cut, it won’t be as quick, clean, and consistent to cut as we’re used to.
Laser cuttability might not be on RBB’s production criteria as it’s a less common application overall than regular woodworking.

The evil 3/4" Birch Ply was at Fine Lumber, right down the road from Assmbly!

I specifically asked for Baltic Birch (they also have some Chinese birch ply there, I think, but I specifically asked for the Baltic). I’ll ask 'em about it the next time I’m there (and I’ll eyeball the sides of the plywood)!

OK was it a 5x5 or a 4x8 sheet?

If it was a 4x8, did you pay approx $161 or $75 for it?

If it was a 5x5, or a 4x8 costing $161, it’s RBB. If it’s a 4x8 costing $75, that was for sure Indonesian/Vietnamese BB. Or there could have been an error where you paid for RBB but they actually handed you Indonesian.

That’s assuming it’s 4x8. If you were handed 5x5, it had to have been RBB, because Indonesian is not made in 5x5.

This underscores one of the most important rules I’ve learned about laser cutting:

Test before you cut, dial in the settings and buy all you need of that same stock.

You never know how the next batch of that same inventory item will differ.

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@dannym whats the actual thickness of the 18mm Baltic birch you use?

18mm Baltic? That would be 18mm

Thats the actual measured dimension? not nominal. I want the measured dimension to use on boxes.py

BB is actual dimensions, in mm. 18mm is sometimes called “3/4 inch”, which is inaccurate, it calipers at 18mm.

Awesome Thanks!!

Closing the loop on this!

The 5’ x 5’ 3/4" plywood at Fine Lumber and Plywood down the road lasers great at speed 5 / power 100 with the focal point near the surface.

The 8’ x 4’ 3/4" plywood there does NOT laser well at all. Obviously their wood/suppliers may change over time. Very easy to tell the difference when you look closely at the plys. The good stuff is on the right of Danny’s photo (pasted here for convenience).

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Sounds like going for the 5x5 sheets, which is known to only come from one source, is the way to go in the short term

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Some glues used in plywoods are definitely not laser-compatible, I’ve had the same issues with other plywoods before, particularly the oak and underlayment materials from home depot.

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Are there settings in the library for 1/2" acrylic?