Reducing current on extruder motor
Hi there, I have some questions about reducing the current on the extruder motor on my MK3s.
I've read that the command M907 controls the current. I'd like to try that for fighting against heat creep. (I know, there are also other solutions against heat creep, but let's talk about M907 now.)
So my questions are:
- What is the factory default current setting for the extruder motor?
- How can I read out the current settings?
- If I reduce the current, what are the disadvantages?
- If I would like to reduce the current for fighting heat creep, what current do you suggest?
If you have any experiences with that topic, I would appreciate if you could share that here. I couldn't find a lot of information about that, especially not in relation to MK3s.
Thanks!
Best Answer by vintagepc:
-You cannot read out the current value. There is an M- (914, I think, or 910) service code but it is disabled in the PR firmware. You would need to recompile it to enable the code.
- Reducing the current reduces the available motor torque. If torque is insufficient, this will lead to skipped steps (extruder clicking) on fast extrusion moves or high volume extrusions where it cannot push/pull with enough grunt.
-I can't tell you offhand what the current value is. I think it's 500-something mA. (I reduced mine to 400 because I have a pancake stepper on my Skelestruder). Either see item 1 or reverse the math to compute it from the #define in the header file for your variant. The value there is "30", the calculation is in the TMC2130 datasheet.
-Setting a value: It's relatively safe to decrease it (vs increasing), undercurrent is unlikely to damage anything. I'd say take the most taxing print you have in terms of retractions and high extrusion volumes (large rectilinear infill areas). Start at (say) 500 and just decrease it until the extruder skips steps. Then bump it back up until it stops skipping, add a bit of extra margin, and you have your new value.
RE: Reducing current on extruder motor
-You cannot read out the current value. There is an M- (914, I think, or 910) service code but it is disabled in the PR firmware. You would need to recompile it to enable the code.
- Reducing the current reduces the available motor torque. If torque is insufficient, this will lead to skipped steps (extruder clicking) on fast extrusion moves or high volume extrusions where it cannot push/pull with enough grunt.
-I can't tell you offhand what the current value is. I think it's 500-something mA. (I reduced mine to 400 because I have a pancake stepper on my Skelestruder). Either see item 1 or reverse the math to compute it from the #define in the header file for your variant. The value there is "30", the calculation is in the TMC2130 datasheet.
-Setting a value: It's relatively safe to decrease it (vs increasing), undercurrent is unlikely to damage anything. I'd say take the most taxing print you have in terms of retractions and high extrusion volumes (large rectilinear infill areas). Start at (say) 500 and just decrease it until the extruder skips steps. Then bump it back up until it stops skipping, add a bit of extra margin, and you have your new value.
RE: Reducing current on extruder motor
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RE: Reducing current on extruder motor
thanks for that until now. very valuable information!
There is still an other question: If i use M907 for changing the current, how long will that setting last? If I turn off the printer, will the printer keep that current for further prints?