steppers with lots of Amp... + M906 command

wilriker

@lb By 50g I meant the total weight of all 4 belts... I have no clue if that is anywhere close to being realistic - I never had the idea of weighing my belts and pulleys.

Danal

@wilriker said in steppers with lots of Amp... + M906 command:

@danal From what the OP added as resources via links this was actually the inertia added by the mass of the pulley and belts themselves. Those 10 to 50 grams.

Agreed, highly variable.

My comment was really in response to (paraphrased): "This can be calculated with just pully diameter". 6mm vs 9mm vs ??? comes into it as well.

So the input might need to be pulley weight & radius, belt width and length... maybe more...

A Former User

@dc42
"stupid" (maybe) question, while digging up new motor-alternatives: Those 2,4A, are they "per phase"? Or in total? I assume per phase.

Because: Let´s say I pick a motor that has 2,12A (1phase), what would be fine... then this motor will have 2 * 2,12A * 1/sqrt(2) -> = ca. 3A then on every two-phase step in total (with only 1,5A on each single phase of course).

genghisnico13

Just because I have everything within arms reach (don't ask), here are the weights:
2m of 6mm Width GT2 belt: 16.11g
16T 6mm W, 5mm ID Aluminum Pulley: 2.92g
20T 6mm W, CR10 stock pulley: 6.10g
All of the above measured with an uncalibrated cheap Chinese scale, so just useful to get an idea.

dc42

@lb said in steppers with lots of Amp... + M906 command:

@dc42
"stupid" (maybe) question, while digging up new motor-alternatives: Those 2,4A, are they "per phase"? Or in total? I assume per phase.

Because: Let´s say I pick a motor that has 2,12A (1phase), what would be fine... then this motor will have 2 * 2,12A * 1/sqrt(2) -> = ca. 3A then on every two-phase step in total (with only 1,5A on each single phase of course).

The 2.4A is the peak per-phase current. When using microstepping, only one phase gets the peak current at a time. When full stepping is selected, both phases get the peak current all the time.

A Former User

@dc42
Thanks so much! That helps me so much to better understand the whole stepper-stuff!

So for learning/understanding:
Even the trinamic-driver in full-step-mode do not scale down to sin(45) = 0,707... * A + cos(45) = 0,707... * A in a two-phase position and have at this time 1.414... times A but with 2 * 1A = 2A in total in a single-phase position
-> That does no user any help because we all have to design our systems for the weakest point then and that is single-phase-on... which means in 2-phase-fullstep with 1*A in each winding I actually have more torque and heat and power consumed then I need because I designed everything in a way it can deal with this less torque in single-phase-on-position that cannot be avoided by any means when using microsteps... (though of course we can think of an always 2-phase full-step-mode)?

Another question design-related:
If I have 3,8rps (=225rpm) in my system with 16times micro-stepping I need 3,75 * 16 * 200=12000pulses per second -> Judging on the 300KHz stated here "https://forum.duet3d.com/topic/3493/maximum-stepper-speed/2" I do not run into any problems, even if in total 3 axis-stepper are mounted + 2 printhead-stepper, because that 300KHz is not limited by the amount of steppers connected?

dc42

The 300kHz was measured with just one stepper motor moving; the figure with 3 motors moving simultaneously was 120kHz. When using external drivers, the maximum rate will be less because of the need to lengthen the step pulses.

Phaedrux

@dc42 Not to hijack the thread, but this makes me curious what the step rate of the Duet 3 will be with a CPU that appears to be about 3x faster. And as a knock on from that, would it be possible to run in native 256x microstepping mode for all axis?

dc42

@phaedrux said in steppers with lots of Amp... + M906 command:

@dc42 Not to hijack the thread, but this makes me curious what the step rate of the Duet 3 will be with a CPU that appears to be about 3x faster. And as a knock on from that, would it be possible to run in native 256x microstepping mode for all axis?

Although the SAME70 that we use on the prototype Duet 3 can do 300MHz, we currently run it at 240MHz because it makes it easier to sync the expansion boards with the main board. This is twice the clock rate of the SAM4E on the Duet 2. Performance doesn't scale with CPU speed because higher speeds need a larger number of flash wait states to be used, although the SAME70 has a cache that helps with this.

I doubt that it will be possible to run with native x256 microstepping on deltas even with Duet 3. However, the stepper drivers support interpolation to x256 from any microstepping, so you would be able to use e.g. x64 interpolated to x256.

A Former User

pulleyRadius? -> Of which pulley, the "main" pulley?

The pulley fixed to the motor shaft.

Thought about it after working for weeks on the hardware, sorry for coming back so late: In a direct-drive-system: yes the pulley attached to the motor, but in a system where the "gear" is realized also with a pulley this could be confusing, so for me I understand you here: In a load/mass-finally-driven-by-pulley-system the "diameter" (pitch) "neutrale Fase" of that "final" pulley moving/attached to the main-mass/toolhead? Am I going way off road here or is that a good assumption?

A Former User

To summarize things up:
In the end, the all-integrated-closed-loop JMC-stepper where the bottle neck because instead of T2.5 what was printed in their datasheet they had to be minimum T3.2, slowing things down...

See thread here:
https://forum.duet3d.com/topic/8847/external-driver-ihss60-connection-question/24

I can see now the benefit of an all integrated solution Cannot wait to see what the duet3 will be capable off!

A Former User

@dc42 said in steppers with lots of Amp... + M906 command:

@phaedrux said in steppers with lots of Amp... + M906 command:

@dc42 Not to hijack the thread, but this makes me curious what the step rate of the Duet 3 will be with a CPU that appears to be about 3x faster. And as a knock on from that, would it be possible to run in native 256x microstepping mode for all axis?

Although the SAME70 that we use on the prototype Duet 3 can do 300MHz, we currently run it at 240MHz because it makes it easier to sync the expansion boards with the main board. This is twice the clock rate of the SAM4E on the Duet 2. Performance doesn't scale with CPU speed because higher speeds need a larger number of flash wait states to be used, although the SAME70 has a cache that helps with this.

I doubt that it will be possible to run with native x256 microstepping on deltas even with Duet 3. However, the stepper drivers support interpolation to x256 from any microstepping, so you would be able to use e.g. x64 interpolated to x256.

I hope you find time (most people do not have any time any more nowadays ) to iterate on the underneath-trinamic-drivers-pcb to have some very good heat-handling either through thick copper-spreads, Vias, possible fan-mount-holes, etc, pp. ... only writing this, because I hope in a year or two the duet3 could be a really great upgrade for the just finished build! Not only because of its new features but also because of top-end-speed and ac-/deceleration... Cheers!