Max speed settings in the base Marlin firmware?

I’m working on tuning my MPCNC for my 10w laser and of course, power and speed are the two main controlling factors. Is there a max speed set in the MPCNC base Marlin firmware? What is it, and can it be increased? What is the physical limit for the machine for movement? I’m not trying to go crazy fast, just wondering how fast I can push it before I need to lower power instead.

The way I understand it, you need to consider 1) max feedrate, 2) starting acceleration, 3) max acceleration. Ryan was testing the impact of running the Rambo board at 12V vs. 24V recently, and gave us some numbers for limits. You can see his post here.

My takeaway from his numbers is that I will likely suffer some sort of laser output quality issue, or Rambo board might not handle g-code throughput, before I reach the speed limits of the machine.

Personally, I’ve just started playing with laser engraving and working with these settings. I set them through g-code that is included as a start script, and I don’t save them with an M500. That means when the control board is rebooted, it will revert to the slower settings, so when I put the router back on, I don’t have to think about making a change (or having an accident). My current settings are:

M203 X900 Y900
M204 P1200 T1200
M201 X1200 Y1200

And the max feedrate I’ve used for an engraving so far is 125mm/s.

Are those settings mm/s or mm/min? You mention 125mm/min for engraving, but that seems awfully slow (.4 mm/s). What power is your laser?

You are right, it is 125mm/s.

Cool. I just used your settings and now my machine fliiiiiies! Woot!

I’ve been trying to dial in settings, and nothing seemed to make much difference, because the machine was locked at 50 mm/s. Time to make some new tests. Thanks for the tips!

M203 uses units per second:

I believe the accelerations are too.