I was wondering about power adjustments to the laser for cutting at certain depths on different types of materials. If it took 80% power at 3 inch a minute speed to cut thru a 1/8" piece of birch, would it be correct to adjust power to 40% power at same speed to cut 1/16" into same material? And with the same token would you also be able to keep at 80% power and double the speed for 1/16" results. I am a self proclaimed laser noob so I was wondering what changes you can make with predictable outcomes.
Unfortunately no - there’s nothing predictable about it. It’s all nonlinear. So (as an example) you won’t penetrate the material at all until you hit some threshold. Then going deeper requires a bit more. Going deeper than that requires a nonlinear amount more. Etc. Worse, speed and power can’t be traded off in a linear fashion (although it’s closer).
It’s one of the big frustrations of laser cutting, and why we will sell materials precoded with the right settings.
Thanks very much for your help!
Dan - If I remember correctly, you also talked about a function that will be available on the Glowforge to help us characterize materials that are not already predefined within the system. Is that correct or was I just dreaming about how that could be done?
While I can’t speak for Glowforge, it’s pretty common for even 2 different lasers of the same laser model and power (say, a 80 watt Trotec) to have slightly different output. Even out of the factory they aren’t always precisely tuned to the exact power they advertise. Many people measure their output regularly and find that their 80 watt machine is putting out 87w when they first receive it.
Additionally, you’ll find that different batches of materials have slightly different properties. So for example if you’re cutting 1/8in plywood the glue on one batch might be denser and require more power/slower speed to get through effectively.
Finally, laser tubes age and eventually fail. So as you put more hours on your laser you’ll see a drop off in effectiveness, and eventually need to replace your tube.
A response to a materials auto calibration question on Oct 4th: