I’ve been using a marking spray that works best at 80% 10w laser and 3000mm/min. I decided to do some cups for a project and noticed that I was having some lost steps when the rotary module was rotating. Mounting of the object was solid… When I lowered the steps to a lower value (1500mm/min), the rotary module was able to keep up with the task.

Luban needs to have limits set for values based on the least capable device. Or, at least a flag that tells you that’s a bad idea.

Just for the information on this thread, I’ve done some in depth testing of this and found the max speed the rotary can do is 2700deg/min. Neither Luban or the Snapmaker controller actually do the math to convert deg/min to mm/min surface speed calculation with the diameter.

However, Lightburn does since version 1.14. It’s better to turn the scan direction 90 degrees so the Y axis moves at the actual set speed, the rotary simply can’t match any real surface speed.

Should not be too complicated… Circumference of a round object is 2πr, where r is the radius. The circumference is 360°. So rotary speed ω [°/s] to linear speed v [mm/s] would be (r in mm):

v = ω 2πr / 360° = ωπr/180°

So 45°/s for an object with 50 mm radius translates to 45°/s x π x 50mm / 180° = 39.3 mm/s

mm/s to mm/min is trivial, just *60s → 39.3 mm/s x 60 s/min = 2356 mm/min.

Or you enter ω in °/min directly, same.

EDIT: for practical use the V_max for different radii, assuming 2700 °/min:

@Hauke Has a very good, in depth explanation, however it can be simplified a bit. Surface speed boils down to Circumference x RPM. So going at our max speed of 2700deg/min, we divide by 360 to convert to RPM, since 1 rotation = 360 degrees.

deg/min ÷ 360 = RPM 2700 ÷ 360 = 7.5 RPM.

To find your maximum surface speed for your object, take the diameter you measure with calipers and multiply buy pi, or 3.14 for simplification to get the circumference . For say a 100mm object (mug maybe?)

d x π = Circumference 100 x 3.14 = 314.

Then multiply together get mm/min surface speed.

RPM x Circumference = mm/min 7.5 x 314 = 2355

Which matches what @Hauke got (minus the rounding error using truncated 3.14). This will be the max speed you can engrave across the surface.

TL;DR Version;

d x 3.14 x 7.5 = Max Speed in mm/min.
Measure the diameter of your object and swap for d