Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)
 
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Carter
(@carter)
Trusted Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Great, I can chop off a few squares... even better, 4-6 copper pennies bent at 90 and thermal taped... done for nada.

Posted : 04/06/2019 3:13 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

The 5th set of thermal vias (last on the right of pict) is the print bed FET. May as well heat sink that while one is at it.

Posted : 04/06/2019 3:18 pm
Carter
(@carter)
Trusted Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Is there a thing such as thermally conductive filament? https://tcpoly.com

 

Here is a common space for just 2 identical heatsinks... It would be great to print them instead of shipping them across the planet.

Here is a start... more later...

 

Attachment removed
Posted : 04/06/2019 4:43 pm
Vojtěch
(@vojtech)
Honorable Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)
Posted by: carter.m2

Is there a thing such as thermally conductive filament? https://tcpoly.com

20x more than PLA is still a very very poor thermal conductivity.

Here is a common space for just 2 identical heatsinks... It would be great to print them instead of shipping them across the planet.

Here is a start... more later...

Cool. Given that heatsinks are available in many many sizes, it should be possible to find some that match what you have in the picture.

 

Posted : 04/06/2019 4:53 pm
bobstro
(@bobstro)
Illustrious Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)
Posted by: carter.m2

Is there a thing such as thermally conductive filament? https://tcpoly.com

That is some interesting stuff. They claim "matches the thermal conductivity of stainless steel". The data sheet says heat deflection temp is only 65C, which raises some concerns, but I don't claim expertise in all things. Would love to see some testing of this filament. They've got some interesting videos of benchmarks using their filament to print phone cases and such.

Great find!

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 04/06/2019 5:08 pm
Carter
(@carter)
Trusted Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

I had purchased these blue AL heatsinks for the 2130's thinking they went on top of the chip, so they were 12.25mm tall...

Four of them fit in the negative space of the vented snap on Pi Zero door... 

Moving on.. back to motors ... but notice the plasma torch negotiation I did in the upper corner...  embarrassing but sometimes it just has to happen.

Attachment removed
This post was modified 3 years ago 2 times by Carter
Posted : 04/06/2019 8:46 pm
evan38109
(@evan38109)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)
Posted by: guy.k2

evan38109 good to see continued work refining the Trinamics. Once you have it better characterized, we can also push it into my 0.9 firmware.

Thanks! That would be awesome!

Posted by: Vojtěch

Same experience here. The Trinamics are a bit more sensitive to stall detection than stock, so raising those thresholds might be considered, but is not required on a smooth moving printer. Also they run cooler than stock, so increasing the current is possible to gain more linearity under acceleration load. I haven't needed heatsinks so far. I'm currently running at

#define TMC2130_CURRENTS_H {20, 24, 35, 30}  // default holding currents for all axes
#define TMC2130_CURRENTS_R {20, 24, 35, 30} // default running currents for all axes

I was just one up from there and have completed a couple hours of printing.  Looking good, but too soon to draw any absolute conclusions. With both them and the 0.9˚ OMCs, I don't think the steppers are the bottleneck any more. We've reached the tipping point in Kuo's Maxim: fix one problem, and you can suddenly see the next problem. ;- )

Posted by: Vojtěch

Congrats! 🙂 How's the quality (and noise) with those [Moons HA6] now?

The noise is manageable, but not absolutely silent. There's a little hash in spreadCycle, and a little squeaking when decelerating quickly unless I keep bumping pwm_grad. Likewise, quality is good, but both the Trinamic -049's and OMC 0.9˚ steppers seem to edge it out at this point. I've had a blast digging in and figuring out how all this works, but I doubt that they're a great fit for this application. Again: this is all very, very preliminary, and I reserve the right to change my mind as I keep tweaking and complete more test prints.

Posted by: Vojtěch

That's going to be a bit tough.

First, you probably don't need to look at both the coils as the waveforms will be the same, as everything is symmetrical. But even a single coil is driven with a H-bridge, so you can't simply connect a single scope probe across it, that'd short-circuit it to ground. You could have some luck if you leave the printer or the scope floating, but you'd see a lot of noise in the signal as both have big capacitive coupling to mains. So either a differential probe, or use two channels on a scope and enable math on the scope to see the difference.

That'd let you see the voltages. But voltages aren't quite interesting, they correlate with the speed of the motor and are influenced by inductance. The important quantity is current, as that's what translates to torque and controls microstepping. It's also what the driver's feedback loop tries to set. For currents, you'll need a current probe or a resistor in series with the motor to measure voltage on. Perhaps the built-in sense resistor could be used, but I worry that thanks to chopping, you'd see both the channels on it mixed together. I'd need to examine the datasheet to confirm.

And,

Posted by: guy-k2

In the old Trinamic tuning thread, I used a current probe to look at the drive waveforms. 

https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-user-mods-octoprint-enclosures-nozzles-.../fine-vertical-artifacts-trinamic-chop-tuning-any-effect/paged/2/

Forum has lots of information, but not much recall. 

Perfect! That's exactly what I needed to get to the next step. I feel a little silly for missing the previous forum post, though. Thanks for you patience with me.

Posted : 05/06/2019 4:34 am
Franji
(@franji)
New Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Hi, I am following this thread closely, I love the work you are doing.

evan38109 I have seen that you have both Trinamic -049 and OMC 0.9, you could upload some photos of your tests with both, a great help when deciding between one and the other. The main reason for what I think of the Trinamic isn't having to modify the firmware.

Posted : 05/06/2019 9:09 am
Albe
 Albe
(@albe)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

OK I'm completely out of ideas with the OMC motors.  Using the guykuo firmware I got the X axis to home fine now - homing stallguard on 2 and speed at 2000 seems to be the happy place.  Now on to the Y axis using defaults just enabling the 0.9 on Y setting it starts a home movement, bumps lighty twice at the home position and then slowly starts moving away (as in about 500 speed slow) for about 4 cm then the printer reboots. 

Now what is interesting I once forgot to set the setting for the Y axis and updated the firmware, then it homes the Y axis fine.

I have swopped the ifdef and ifndef values for Y in Configuration_prusa one by one to get a working setting so that it homes at least but still no joy.

Any other suggestions or files I should look at?

Posted : 05/06/2019 2:21 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Uh.... Don't mess with the def's and ndefs unless you understand what they are doing. I would revert back to a fresh copy to ensure you don't have one deleted or inverted.

The OMC runs back and forth OK when you manually move the axis in menu? If not verify your wiring harness is set up for OMC/Moon's convention rather than LDO.

If it moves OK, but simply having homing difficulty, my first inclination is to check why the Y motor isn't registering a SOLID hit during homing. I think you are on linear rails. What did you arrange as the replacement impact stop for Y-homing? It has to be a solid stop to register correctly, especially with the reduced feedback of a 0.9 motor.

Posted : 05/06/2019 5:01 pm
Albe
 Albe
(@albe)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)
Posted by: guy.k2

Uh.... Don't mess with the def's and ndefs unless you understand what they are doing. I would revert back to a fresh copy to ensure you don't have one deleted or inverted.

The OMC runs back and forth OK when you manually move the axis in menu? If not verify your wiring harness is set up for OMC/Moon's convention rather than LDO.

If it moves OK, but simply having homing difficulty, my first inclination is to check why the Y motor isn't registering a SOLID hit during homing. I think you are on linear rails. What did you arrange as the replacement impact stop for Y-homing? It has to be a solid stop to register correctly, especially with the reduced feedback of a 0.9 motor.

Swopped the settings to switch the settings one by one between your code and original prusa code.

I have a printed stop at on the rails on the rear where the blocks hit during homing.

Just want to highlight this again - everything works as expected running on default Prusa firmware, the h0ming issues is only using the tuned firmware.  On there the only changes I need to make is dropping steps to 1/8 and obviously the moving distances which is different.

Posted : 05/06/2019 5:07 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

How long is your Y-carriage length vs the stock carriage? There is a distance range the printer expects. However, it is extremely puzzling that using the same motor works with vs without the 0.9 degree motor software.

Is your motor actually a 0.9 degree unit? I started my 0.9 journey because I was shipped the wrong motors.

Be certain the three def's in configuration_prusa.h of my firmware matches the motor. Only those defs should be changed. They trigger everything else.

For example, with all motors being 0.9 degree units...

#define X_AXIS_MOTOR_09 //kuo exper
#define Y_AXIS_MOTOR_09 //kuo exper
#define E_AXIS_MOTOR_09 //kuo exper

If only X and Y are 0.9 units...

#define X_AXIS_MOTOR_09 //kuo exper
#define Y_AXIS_MOTOR_09 //kuo exper
//#define E_AXIS_MOTOR_09 //kuo exper

The firmware settings MUST match the actual motor type or it simply won't work. All the other micro step stuff is automatically taken care of for you (if you don't alter what I wrote).

 

This post was modified 3 years ago by Bunny Science
Posted : 05/06/2019 5:26 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

I am very suspicious that your Y-axis OMC is a 1.8 degree unit because it works with stock firmware, but not my 0.9 degree firmware. The default config in my firmware is for 0.9 motors on XYE.

If your Y is a 1.8 degree, but X and E are 0.9's

#define X_AXIS_MOTOR_09 //kuo exper
//#define Y_AXIS_MOTOR_09 //kuo exper
#define E_AXIS_MOTOR_09 //kuo exper

This post was modified 3 years ago 2 times by Bunny Science
Posted : 05/06/2019 5:34 pm
Albe
 Albe
(@albe)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Motors are 17HM15-0904S. 

 Y distance with the blocker at the end is the same otherwise XYZ  calibration fails. 

I've done a quick swop between X and Y motors to rule out a fried motor. Did a fresh reload now, this is what I did:

Cloned github source again, copied Mk3S file from variants and renamed.  Checked config.h for language setting.

Then in configuration_prusa.h changes this:

Uncommented

#define X_AXIS_MOTOR_09
#define Y_AXIS_MOTOR_09

#define BMG_Extruder

Changed

#define TMC2130_SG_THRS_X_HOME 2

X homes fine, Y does the bump, slow move then the printer reboots.

What happens that causes the printer to reboot? Current draw?

Posted : 05/06/2019 5:50 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

I'm assuming your already verified  zero binding of y-axis with belt disconnected.

That is same motor I am running on Y. There is something going on that is beyond normal behavior. Reboot happens when firmware finds itself in unexpected state. Overcurrent typically will show a TMC_overheat and then reboots.

I suggest ruling out mangled EEPROM data with a full factory reset including data.

Posted : 05/06/2019 6:05 pm
Albe
 Albe
(@albe)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

OK will do that. 

Will let you know what happens

 

Posted : 05/06/2019 6:07 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Fingers crossed. This is really peculiar behavior. 

Prusa did significantly alter how values are store and recovered from EEPROM in 7.1

So, this is worth ruling out.

Posted : 05/06/2019 6:26 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

BTW, I just executed mergedfrom Prusa's MK3 branch a few minutes ago. Should be caught up with their most current firmware.

Posted : 05/06/2019 6:30 pm
Albe
 Albe
(@albe)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Had to put kids to bed first.

Looks you you hit the nail on the head... Printer passed all the self tests now, doing XYZ calibration at the moment.

I did do a few homing moves before the XYZ now - all looks good so far.

One thing I had to change though for the BMG is the Z height - dropped it to 205.

 

Posted : 05/06/2019 7:25 pm
Albe
 Albe
(@albe)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Update - It worked!!

I'll remember this now - anything weird - FACTORY RESET, ALL SETTINGS.

Thank you very much @guy-k2

Posted : 05/06/2019 7:31 pm
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