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.
In general this speed limits are set in the controller firmware.
You could check your settings with M503 in the console.
If there are lost steps there seems a defect or a inproper gcode.
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.
Thanks for sharing this - it is surprisingly consistent with what Snapmaker claims on the shop page - 45°/sec = 2700°/min:
For the non-math inclined, how would I back calculate the 2700 degrees per minute into a mm/min?
That’s the real problem.
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.
d x 3.14 x 7.5 = Max Speed in mm/min.
Measure the diameter of your object and swap for