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Laser cutting 1/8" plywood on a Full Spectrum laser cutter

So it turns out that there is actually a very big difference between cutting the various types of 1/8" hobby plywood! I had no idea.

I bought my plywood from National Balsa. They offer three types of 1/8" hobby plywood:

1. Lite ply, which is very light but not too strong. Apparently it is made from poplar. Very flexible. I haven't tried to cut it, but would imagine that it cuts easily.

2. Regular, 3-ply plywood which is called birch, but seems to clearly be not as refined as 6-ply. Much stronger than Lite ply, but a bit heavier too. Cuts really well! Less reflective, fewer layers which means less resin to melt.

3. 6-ply birch plywood. This is actual birch. Very reflective, strong and solid. Tough to cut! 6 ply's mean lots of resin to melt.

They also offer both 1/16" and 1/32" birch ply.


So, the other day when I was laser cutting my frames, I was able to easily cut through the first two sheets. Then on the third sheet, the laser was incredibly bright and flames were shooting off of the plywood! Yikes!

Turns out that that third sheet was actually the 6-ply birch plywood. I had ordered both regular 3-ply non-birch and 6-ply birch. My initial idea was that I would use the regular to do the test-hull, and then the good stuff (6-ply birch) to do the real boat. Now I'm convinced that the best way to go is with just the regular stuff.

I laser cut the regular 1/8" 3-ply on our Full Spectrum 90 watt laser at 60% speed and 45% power with one pass. It cuts very well and just barely releases the parts. There is little scorching and the cuts are vertical.

When I cut the birch however, I had to do many test runs. Turned out that the best setting to cut it was at 50% and 100% power with one pass. Multiple passes only scorched the wood even more. Even at the 50/100/1 setting, the cut was still very burned and had a noticeable angle to it. Yet it was the cleanest of all the test cuts I did. At this point, I'm not sure how to cleanly cut the 6-ply stuff.

My guess is that the birch is a much more reflective and harder surface than the regular stuff. I got similar reactions when I cut the 1/16" and the 1/32" sheets too which are only 3-ply, although due to cutting faster, and the thinner material, the scorching wasn't too bad. I'll continue to use birch when I need thin sheets, but at 1/8" I'll only use "regular" plywood.


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