The purpose of this instructable is to describe the settings I have had success with in cutting out 1/8" and 3/16" plywood for model airplane parts. This is for using 5 ply aircraft 1/8" ply and 4 ply aircraft 3/16" ply. These are the settings used for a 60 watt Epilog laser cutter that is available to use at Tecshop Detroit.
I made it at TechShop
Step 1: What Doesn't Work Well
At Techshop, there is a sheet with generic settings for cutting parts on the laser cutters. The speeds shown for wood and plywood are 90% power at 20% speed. I started off with these settings. To cut 1/8 5ply wood required 7 passes and the parts still weren't dropping out of the sheet. To cut 3/16" 4 ply wood required 10 passes with the parts not coming out of the sheet.
If you look at the edges of parts cut this way there is a lot of burning on the wood and noticeable angle to the edges. They do not cut cleanly at all. I think that with the slow speed, the adhesive layers in the plywood are melting and reacting preventing you from getting a good cut.
Step 2: What Does Work Well
To try something else, I set the speed much faster on the laser cutter. This time I tried cutting at 60 speed/90 power/500 hz.
This time the results were as follows:
1/8" 5 ply wood cut cleanly through at 4 passes and the parts were dropping out of the sheet.
3/16" 4 ply wood cut cleanly through at 8 passes with parts falling out of the sheet.
If you look at the parts, the are much cleaner this time and the edges are much more square. Running the laser faster seemed to avoid a lot of the charing of the edges of the parts. It required less passes with the laser to completely cut out the parts.