Steps/mm configuring

(Al57_SW) #1

I am using a smoothieboard in a CNC application. The x,y & z axes are ball screws driven by 36Tooth GT2 pulleys connected to a 20 Tooth ? pulley on the stepper motor. I am calibrating the axes at present and Its around 1450 steps/mm on the 3 axes. That’s a lot higher than the 80 steps/mm I used on a previous belt driven machine.
The machine appears to work well (homing and basic movement) with these settings (with reduced speed and acceleration settings), but I was wondering if having such high step/mm values will affect smoothiebord/machine operation or motor performance eg overheating or significantly reduce motor life. Is there an acceptable range or max value for steps/mm?
If so one option would be replacing the 36t gear with 20T which should reduce this value.

Imported from wikidot


(gavinmetzler_SW) #2

The smoothieboard max step rate is 100khz (3 axis), so with 1450 steps/mm your maximum feed speed would be 4138mm/min. If this is a mill, thats probably fine. If its a wood router, this may be a bit slow.

The other option of course is to change your microstepping rate. What do you have it set at? How did you come up with the 1450 steps/mm?


(Al57_SW) #3

Thanks for the reply.
I decided to change the gearing down to 1:1 on X+y axis they are now around 805 steps/mm. it is a mill application so far it seems ok.