Stepper Settings Tuning Questions

gnydick

I've got these motors for X & Y. LDO 42STH60-2004MAC

Here is the diagram and specs, and here is the torque curve.

At that setting, the max usable performance is something like this before I skip steps

# experience is that the print head is very delicate and can easily be moved by hand under holding force

M350 X16 Y16 I1

M566 X400 Y400
M203 X12000 Y12000
M204 X6000 Y6000

However, this is what I get with tweaked microstepping

# with these settings, the carriage is incredibly powerful. I'm literally afraid of it. It has the ability to smash other parts of the printer to bits if something is not homed properly.

M350 X32 Y32 I0

M566 X1400 Y1400
M203 X25000 Y25000
M204 X11000 Y11000

Based on all of the collective wisdom here, I've always been told to run 16 steps with interpolation.

After looking at the crazy increase in performance, I'd like to know what's going on.

Why is 16 I1 always recommended?
What are some actual calculations/techniques to figure out the best settings?
It is a bit louder with the new settings, but it doesn't seem to be any less smooth. Though at low speed it is VERY loud.

I feel like there is information I'm missing.

Phaedrux

16x with interpolation is recommended because it has a lower CPU load due to step generation and the stepper drivers have an internal interpolation to result in 256x at the stepper for smoother, quieter operation.

As fo the differences in performance that you're seeing, I'm not sure. How did you determine those values? What's your testing methodology?

gnydick

@Phaedrux purely empirical. If I try the higher perf settings with 16+I then the carriage constantly starts to move then locks and squeals.

Phaedrux

@gnydick said in Stepper Settings Tuning Questions:

purely empirical

I'll get right on trying to duplicate that then.

T3P3Tony

@gnydick said in Stepper Settings Tuning Questions:

M566 X1400 Y1400
M203 X25000 Y25000
M204 X11000 Y11000

you have different settings for the different microstepping settings so movements are not really comparable.

are you also running different currents?

gnydick

@T3P3Tony the settings represent the max'ed out performance achievable for each microsteppings setting. It was just a convenient way to communicate the numbers.

deckingman

@gnydick It looks like you've changed both the microstepping and the interpolation. What happens if you leave it at 16X but turn interpolation off? It wouldn't surprise me if you can get higher acceleration without interpolation but movement will be harsh, imprecise and noisy which will lead to all sorts of resonance issues and print aterfacts.

gnydick

@deckingman, so you're saying my experience is expected?

deckingman

@gnydick said in Stepper Settings Tuning Questions:

@deckingman, so you're saying my experience is expected?

I'm not sure. All I'm saying is that if someone more knowledgeable than me, told me that microstepping might lead to a reduction in maximum torque that a motor can produce then I'd believe them. Essentially (as I understand it) micro stepping chops each full step into 16 (or whatever microstepping is set to) smaller steps. To do that, it must of necessity supply 1/16th of the full step current per microstep. So between each full step, there would be an incremental increase in current. Although the maximum current at the end of the last microstep would be the full current, the average current for all 16 microsteps would be about half that maximum. At least that's how I see it but someone more knowledgeable than me might correct me.

Either way, you could prove it yourself if you changed only the interpolation but left the microstepping value unchanged. If you find that your motors produce more torque with interpolation turned off, and you need that torque and can live with the resultant harshness, noise and lack of resolution, then go for it.

gnydick

@deckingman, yeah, that would be my intuition as well. My question is really around why "we" suggest what we do almost as gospel.