XY Stepper Motor Specifications  

Re: XY Stepper Motor Specifications

you got me curious, I found this (from the older model though):
https://shop.prusa3d.com/forum/prusa-i3-kit-archive--f84/are-all-5-stepper-motors-the-same--t1501-s10.html

the 1684 is close but my x/y are 42x39
http://ldomotors.com/products/show/42mm-hybrid-stepper-series

Re: XY Stepper Motor Specifications

Don't forget, if you double the steps, you halve the maximum speed...

The 8-bit MPU can only output a limited number of steps.

And the X/Y motor resolution is already better than the printer can handle and most people can measure (10 microns).

Peter

Re: XY Stepper Motor Specifications

It's not recommended for the 3 axises, but for the E stepper motor it can be an (little) improvement.

As Peter report, most of it can't be measued.

Thomas

Re: XY Stepper Motor Specifications

Then again on the Mk3, the E motor now runs at 280 steps/mm, so very little to be gained by changing that motor.

If you did, then you would be limiting E to around 25mm/s (or just above) and may lose steps if you try to retract any faster than that.

Peter

Re: XY Stepper Motor Specifications

Yes correct, for the MK3 it's not really usefull.

Thomas

Re: XY Stepper Motor Specifications

Then again on the Mk3, the E motor now runs at 280 steps/mm, so very little to be gained by changing that motor.

If you did, then you would be limiting E to around 25mm/s (or just above) and may lose steps if you try to retract any faster than that.

Peter

I'm currently at 1626 E steps with my Titan and the 0.9 degree stepper that comes with it, and i'm printing infill at 170mm no problems.

Since i've built my printer with full aluminum extrusions, i want to go even faster for the infill, i think i can get up to 320mm no prob with a few value changes in the firmware.

I kinda only wanted half the E steps, i think i'll change the 32 microsteps to 16 in the firmware for the E axis.

Edit: here are the specs for the Prusa motors (look at randys reply for the correct specs)
https://shop.prusa3d.com/forum/hardware-firmware-and-software-help-f64/sensorless-homing-with-third-party-motors-doesn-t--t17528.html

And don't change the X/Y motors, sensorless homing isn't programmed for those, and you'll lose speed.

Re: XY Stepper Motor Specifications

i'm printing infill at 170mm no problems.

Doh! That's the X/Y speed 😀

And with acceleration and Jerk, I doubt you are even getting 170mm/s on most models.

170mm/s @ 0.2mm layer height and 0.4mm extrusion = 13.6 mm^3/s = 5.67 linear mm/s extruded. And that, by the way, is 2mm^3/s more than E3D believe the maximum melt volume of the V6 actually is, before print quality deteriorate rapidly due to lack of fluidity.

Peter

Oh, Back EMF sensing works on all motors (if you know what you are doing).

Re: XY Stepper Motor Specifications

i'm printing infill at 170mm no problems.

Doh! That's the X/Y speed 😀

And with acceleration and Jerk, I doubt you are even getting 170mm/s on most models.

170mm/s @ 0.2mm layer height and 0.4mm extrusion = 13.6 mm^3/s = 5.67 linear mm/s extruded. And that, by the way, is 2mm^3/s more than E3D believe the maximum melt volume of the V6 actually is, before print quality deteriorate rapidly due to lack of fluidity.

Peter

Oh, Back EMF sensing works on all motors (if you know what you are doing).

Am i missing apples with oranges again? Seems like it.
Thanks for the bonk to the head then about the volumetric speed instead of linear speed. I need that sometimes.

Anyway, about the speed thing; if this old fossil can do it, i should be able to do it, too.

The cube in the video no doubt got thrown into the trash immediately after, but half as fast should be doable.

> Oh, Back EMF sensing works on all motors (if you know what you are doing).

This is where i currently have problems with. Naturally this works, but because of Prusa's 6.5V motors the settings are so off for my 1.2V motors i can only guess which settings i have to change to get sensorless homing to work.

Re: XY Stepper Motor Specifications

This is where i currently have problems with. Naturally this works, but because of Prusa's 6.5V motors the settings are so off for my 1.2V motors i can only guess which settings i have to change to get sensorless homing to work.

OK, so voltage is mainly irrelevant with stepper motors; they are current-limited by the drivers.

The current Trinamic drivers handle a maximum current of (from memory) 1.4 Amps, but are limited by firmware (motor power) settings.

Basically, your stepper motors need to be able to take a balanced voltage and current; the resistance/impedance of the motors determines this. If you have 1.2V motors, then they will have very low resistance/impedance (therefore high current) and the Back EMF will not register in the controller as expected. However, the motors will be working on reduced power - the firmware current will be met with a much lower voltage, which may cause you problems (but if you are using a geared extruder = torque/power multiplier, that should be OK).

Peter

EDIT: but please be aware that PR Marlin is much more complex than vanilla Marlin and the load on the MCU is way higher...

Re: XY Stepper Motor Specifications

the Back EMF will not register in the controller as expected

Yeah, which is why replacement motors on X, Y and Z don't work right. I figure the detection on E also doesn't work right, but whatever, it prints)

What do you think, with 2.2V/2A/1.1R should i up or down the currents? (compared to Prusa's 6.5V/1A/6.5R motors)

Holding and running currents work so far with stock settings (16/20/30/32), but homing doesn't work reliably with these values (8,10,20,18)
Didn't get the time to make a new FW and test it, will have time on the weekend. Asking bc a second opinion is always nice.
(i think i should go to 12/14/24/22 for the homing currents, basically a +4 in scalar value, perhaps this works.)

EDIT: but please be aware that PR Marlin is much more complex than vanilla Marlin and the load on the MCU is way higher...

Yeah, i think i should go down to 16 microsteps for the E axis, 1626 is too overkill.
I'm not printing with OctoPrint yet on the MK3 clone, but i figure this crazy step value won't be good in to long run

Re: XY Stepper Motor Specifications

Problem will be if you increase the firmware current limits, you increase the stepper driver voltage as well as the current.

You could end up burning out your motors, so I really would suggest you get higher voltage motors or leave well alone.

There was a time when I could work all this stuff out, but being old and decrepit, it's now way beyond my capabilities 🙁 Sorry.

Peter

Re: XY Stepper Motor Specifications

Problem will be if you increase the firmware current limits, you increase the stepper driver voltage as well as the current.

You could end up burning out your motors, so I really would suggest you get higher voltage motors or leave well alone.

There was a time when I could work all this stuff out, but being old and decrepit, it's now way beyond my capabilities 🙁 Sorry.

Peter

Aw man, i'm pretty naked on this, thought you would know.

Asked around reprap forums, reddit and here, nobody's really done this before?
The TMC2130 aren't common, and the ones that do use them are the daughterboard drivers with a trim poti and without SPI,
And the TMCs what the Voron/CoreXY builders use are TMC22xx, which don't have stallguard.

Burning out motors may not be the case, but i have had some issues with the TMCs overheating during autohoming. A fan directed at the driver chips helped, but it's the wrong solution.
We'll see. Either i'll get it to work somehow, or i'll nuke the Einsy.

Re: XY Stepper Motor Specifications

Aw man, i'm pretty naked on this, thought you would know.

OK, yeah, sorry. But I am not going to tell you to do something that I haven't tried myself and with the potential to do damage and cost you money!

You could measure the resistance of the motor coils and do some basic calculation from that.

TMC drivers have reduced current output, I believe this is an attempt to reduce the possibility of overheating. They should also have thermal protection built in. But when you are using high current motors (low voltage and resistance), without doing the math, who knows?

Peter

Re: XY Stepper Motor Specifications

Thanks for the links @curtis.c2!

I dug into the datasheet for the Trinamic TMC2130 drivers on the Einsy Rambo 1.1. It looks like up to 2.0 [A] per coil should be fine, provided that heat is dissipated properly on the PCBA layout. (I should probably get heatsinks if I'm worried.)

Cool! I just wanted to drop in a 0.9-degree stepper without blowing my Einsy.

I'm hypothesizing that the current layer-inconsistency issue ( https://github.com/prusa3d/Prusa-Firmware/issues/602 ) is from pushing the microstepping limit to beyond what's practical resulting in hitting inconsistent locations. My plan is to swap for 0.9-degree steppers and cut the microstepping factor in half.

Re: XY Stepper Motor Specifications

I'm hypothesizing that the current layer-inconsistency issue ( https://github.com/prusa3d/Prusa-Firmware/issues/602 ) is from pushing the microstepping limit to beyond what's practical resulting in hitting inconsistent locations.

No that is not the cause. The MMU helped to identify the micro step limit and the Mk3 doesn't really approach that.

My plan is to swap for 0.9-degree steppers and cut the microstepping factor in half.

That is a better way to go, but the drivers will still interpolate to 1/256 stepping. And there are issues with this interpolation. Much better with the stepper drivers from the Mk2 and running 1/8 stepping (except for E).

Peter

Re: XY Stepper Motor Specifications

This is where i currently have problems with. Naturally this works, but because of Prusa's 6.5V motors the settings are so off for my 1.2V motors i can only guess which settings i have to change to get sensorless homing to work.

OK, so voltage is mainly irrelevant with stepper motors; they are current-limited by the drivers.

The current Trinamic drivers handle a maximum current of (from memory) 1.4 Amps, but are limited by firmware (motor power) settings.

Basically, your stepper motors need to be able to take a balanced voltage and current; the resistance/impedance of the motors determines this. If you have 1.2V motors, then they will have very low resistance/impedance (therefore high current) and the Back EMF will not register in the controller as expected. However, the motors will be working on reduced power - the firmware current will be met with a much lower voltage, which may cause you problems (but if you are using a geared extruder = torque/power multiplier, that should be OK).

Peter

EDIT: but please be aware that PR Marlin is much more complex than vanilla Marlin and the load on the MCU is way higher...

got the sensorless homing with third party motors working.
https://shop.prusa3d.com/forum/hardware-firmware-and-software-help-f64/sensorless-homing-with-third-party-motors-doesn-t--t17528.html#p86719