@Atthis It depends on the wood but in general i use 100 'speed' for cutting. I have tried a few different types of ply at 2.4mm of which some cut in 2 and some in 5 passes. Really depends on the quality of the wood.
@Spiderik It is possible your Nano has lost the boot loader, the best way to check is use XLoader (a great little utility which also uses avrdude). If you have another Arduino or an Atmel programmer you can reload the boot loader and hex, if not you would need to get a replacement Nano or find someone to help you.
This isn't very common but can happen if you have a poor USB cable or connection and it becomes corrupt during the flashing process.
@nottingham82 Agree with all your points. Just add some personal experiences in order to help who starts in cutting plywood. Parameters involved:
laser power (of course, use max value) (I have 2.5W)
n. of passes (as stated by nottinghm82, 6 is a good starting point. I run tests using a 2 cm circle, most of the tools allow easily to do it)
plywood thickness (of course. Recently I have used 3 mm poplar)
plywood type (poplar is fine, even if different lots behave quite different. Birch required a lot of additional passes)
air assist is a key point
focusing point (it seemed to me that it is better to focus on the lower part of the plywood. Other experiences?)
Another interesting point: swapping speed and n. of passes?
I mean: doubling the speed and the n. of passes ensure the same cutting power?
In my experience, this improves a bit the burning of the wood. But this works within certain limits, speeds between 100 and 400 are sometimes ok. Other experiences, opinions?
Thanks for sharing