They recently changed it to be from in/min to made-up units. I’m not much of a fan, but then again I would have preferred mm/sec over in/min.

The current implementation is something like (in/min + 4)*2. It’s hidden somewhere in a spreadsheet linked on the forums.

I’m hoping they will add an advanced mode in the future that lets you specify your units for speed.

Other than the speed situation, I like what they’ve done with the power/dithering section. Really looking forward to trying it soonish. (Whenever mine arrives)

The annoying thing for me is the software is metric underneath and the limits are round numbers in metric but was converted to IPM for the GUI and gave ugly limits. If they had just switched to mm/minute in the GUI they would have had nice round numbers that made sense. I.e twice as fast is double the number and both cut and engrave in the same units.

4 ipm was actually 100mm/min, 157 was 4000mm/min. 335 was 8500mm/min.

So all that formula does, is take the first set of A and B as old min/max, and the second row of A and B as the new min/max, and makes a linear conversion between them. So 4 goes to 100 and 157 to 500. The first set is presumably the min/max limits in IPM that are “reasonable” for cut/engrave, and that is mapped to a 100-500 or 1000 scale. The engrave max speed is approximately 2x as fast as the cut speed limit, although not exactly, so that’s probably why they doubled the scale.

Yeah I understand how it works, I just think it’s unnecessary and makes converting between other things that much more painful.

Not really sure if they wanted to make a nice big round number, or were trying to hide the fact max speed on a Glowforge is a lot slower. Could be both…

Either way, neither of those are really doing a service to the user. I’m hoping in future versions they will allow you to choose the units it displays.

Wish we knew the formula. I’m trying to figure out a dwell time for every setting. So that for say I have it at x power and y speed i can say g delivered but I may want to run it faster so that means less dwell time so more powered needed to get the same delivered

We do know the formula. It is the simple linear transform you graphed. It is the fact it has an offset that makes it awkward for energy density calculations. But we don’t know how power is mapped so you can’t do that anyway.

If I ever get mine I will try to work out the power mapping and check the speed mapping is real.