Prusa upgraded to duet, weird extrusion

[droftarts]

@Veti Ah yes, of course. Might still be strange meshing of the two filament drive gears, though.

Ian

[Murloc992]

@Veti said in Prusa upgraded to duet, weird extrusion:

@droftarts said in Prusa upgraded to duet, weird extrusion:

Looking back, are your e steps per mm 276 still? I think they should be around 410 for BMG with 1.8 degree motors,

its a prusa. so no 3:1 reduction. thats just the normal around 100 something increased by the 0.9 stepper.

If to be completely accurate: 133 default, 138 after calibration with 1.8' motor. 276 with 0.9' motor. Steps are spot on.

@droftarts said in Prusa upgraded to duet, weird extrusion:

Is there any chance you’ve assembled the extruder incorrectly? Feel free to post pictures!

Not a chance. I've owned this printer for several(3+) years by now. Went through MK2.5S, MK2.5X(custom), MK3 "hybrid"(adapted for 2.5), bear extruder. Never assembled it wrong.

Here's how my filament is going through the main bondtech gear:

@droftarts said in Prusa upgraded to duet, weird extrusion:

@Veti Ah yes, of course. Might still be strange meshing of the two filament drive gears, though.

Ian

Meshing seems fine, but I will try putting in 623 bearing idler after I customize it.

[NitroFreak]

I know what it might be. In the Prusa bear thread they talked about how the 0.9 might not have enough torque to direct drive the extruder.

I just read that you‘re using the 12v PS.
0.9 degree steppers really want 24v otherwise you will not be able to reach good speeds and torque, because you literally only have half the torque vs 24v and torque is further halved because you have the 0.9 instead of a 1.8 stepper. I could imagine the extruder is lacking until it reaches the next full step where it snaps to, resulting in this sort of extrusion inconsistency.

I would suggest you try a 24v power supply

[Murloc992]

@NitroFreak said in Prusa upgraded to duet, weird extrusion:

I know what it might be. In the Prusa bear thread they talked about how the 0.9 might not have enough torque to direct drive the extruder.

I just read that you‘re using the 12v PS.
0.9 degree steppers really want 24v otherwise you will not be able to reach good speeds and torque, because you literally only have half the torque vs 24v and torque is further halved because you have the 0.9 instead of a 1.8 stepper. I could imagine the extruder is lacking until it reaches the next full step where it snaps to, resulting in this sort of extrusion inconsistency.

I would suggest you try a 24v power supply

I actually once pushed filament out at 60mm/s, 100mm of it. Nothing skipped. The speed of the extruder wheel spooked me quite a lot though.

Yeah, sounds good, but I have 12V bed, 12V heater, 12V fans, etc..

[Veti]

did you try the original 1.8 stepper again? you initially wanted to get rid of the vfa, which only need the swap of the x and y stepper.

[NitroFreak]

@Murloc992 said in Prusa upgraded to duet, weird extrusion:

@NitroFreak said in Prusa upgraded to duet, weird extrusion:

I know what it might be. In the Prusa bear thread they talked about how the 0.9 might not have enough torque to direct drive the extruder.

I just read that you‘re using the 12v PS.
0.9 degree steppers really want 24v otherwise you will not be able to reach good speeds and torque, because you literally only have half the torque vs 24v and torque is further halved because you have the 0.9 instead of a 1.8 stepper. I could imagine the extruder is lacking until it reaches the next full step where it snaps to, resulting in this sort of extrusion inconsistency.

I would suggest you try a 24v power supply

I actually once pushed filament out at 60mm/s, 100mm of it. Nothing skipped. The speed of the extruder wheel spooked me quite a lot though.

Yeah, sounds good, but I have 12V bed, 12V heater, 12V fans, etc..

i doubt it was pushed out at 60mm/s , even my volcano with a BMG grinds filament after 12mm/s filament speed. Maybe you mean print speed? or mm/min?
If you do not want to convert to 24v, i suggest your best bet would be to put the 1.8 degree stepper back in or use a 3:1 gearing

[droftarts]

Fair enough re assembly, just running out of ideas! @NitroFreak isn’t quite right about torque of 0.9 motors (see https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors#Section_Step_angle ) except at high speed, but the extruder doesn’t turn that fast. Powering with 24V would be a better option for 0.9 degree motors, though.

Ian

[Murloc992]

@NitroFreak said in Prusa upgraded to duet, weird extrusion:

@Murloc992 said in Prusa upgraded to duet, weird extrusion:

@NitroFreak said in Prusa upgraded to duet, weird extrusion:

I know what it might be. In the Prusa bear thread they talked about how the 0.9 might not have enough torque to direct drive the extruder.

I just read that you‘re using the 12v PS.
0.9 degree steppers really want 24v otherwise you will not be able to reach good speeds and torque, because you literally only have half the torque vs 24v and torque is further halved because you have the 0.9 instead of a 1.8 stepper. I could imagine the extruder is lacking until it reaches the next full step where it snaps to, resulting in this sort of extrusion inconsistency.

I would suggest you try a 24v power supply

I actually once pushed filament out at 60mm/s, 100mm of it. Nothing skipped. The speed of the extruder wheel spooked me quite a lot though.

Yeah, sounds good, but I have 12V bed, 12V heater, 12V fans, etc..

i doubt it was pushed out at 60mm/s , even my volcano with a BMG grinds filament after 12mm/s filament speed. Maybe you mean print speed? or mm/min?
If you do not want to convert to 24v, i suggest your best bet would be to put the 1.8 degree stepper back in or use a 3:1 gearing

Maybe the motor skipped and I didn't hear it? I can try putting the original motor back in, but it also was pulsing, just less.

Like that:

[droftarts]

How about the other way around; maybe you have the idler overtightened and the BMG gears are meshing badly because they’re too tight?!

Ian

[Murloc992]

@droftarts said in Prusa upgraded to duet, weird extrusion:

How about the other way around; maybe you have the idler overtightened and the BMG gears are meshing badly because they’re too tight?!

Ian

I have tried the "correct tension" method: so that it just grabs with minimal tension and ofc overtightening, no difference. BUT I have an idea. Let me check.

[Murloc992]

Nevermind.. I tried limiting the side-to-side play bondtech idler has, even played with currents throughout the layers and nothing seemed to give any effect. I went from original 1200mA, to 1400, 1600, then tried going lower, 1000, 800, 600, 400. It never skipped, the print looks identical. The print is a very slow single wall cube print. 15 minutes for 25x25x25mm.

[Murloc992]

Fun fact: if I extrude using the web control at 5mm/s, there's no pulsing. If I extrude at 15mm/s (no skipping till 4 in a row, must be heat related) it's extremely smooth. If I extrude at 1mm/s, it pulses INSANELY.

[NitroFreak]

thats because of the firmware minimum speed of 1.5mm/s iirc?

[droftarts]

@NitroFreak said in Prusa upgraded to duet, weird extrusion:

thats because of the firmware minimum speed of 1.5mm/s iirc?

It’s 0.5mm/s. from Gcode dictionary in G1 definition:

For CNC users especially: RRF has a default minimum movement speed of 0.5mm/sec. In firmware 2.03 and later this can be changed using the I ('i') parameter of the M203 command.

Ian

[droftarts]

@Murloc992 not sure when Back EMF kicks in? See https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors#Section_Back_emf_due_to_rotation

Ian

[Murloc992]

@droftarts said in Prusa upgraded to duet, weird extrusion:

@Murloc992 not sure when Back EMF kicks in? See https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors#Section_Back_emf_due_to_rotation

Ian

Not sure...

Would toying around with CHOPCONF values help here?

[Veti]

@Murloc992 said in Prusa upgraded to duet, weird extrusion:

Would toying around with CHOPCONF values help here?

no but increasing voltage helps

[Murloc992]

@Veti said in Prusa upgraded to duet, weird extrusion:

@Murloc992 said in Prusa upgraded to duet, weird extrusion:

Would toying around with CHOPCONF values help here?

no but increasing voltage helps

I literally spent a ton of money on the upgrade.. Just thinking about spending even more on a 24V setup hurts me inside.

[Veti]

@Murloc992
i dont think you are gonna reach any speed where the emf becomes a problem with the extruder.

[Murloc992]

@Veti

Then what do you mean

@Veti said in Prusa upgraded to duet, weird extrusion:

no but increasing voltage helps

Aren't you talking about the main PSU? Or Stepper voltage?