Duet WiFi and stepper motor Failrues

idmurp

Can can confirm that the weak stepper is now weak on both the X and Y Axis circuits. If I plug a new motor into either of those circuits it works fine.

The stepper is now at fault, and its the 3rd occuance in 2 different makes of steppers on this printer which has hardly seen any use.

dc42

Do the stepper motors have permanently-wired cables, or detachable cables?

Phaedrux

@idmurp said in Duet WiFi and stepper motor Failrues:

17HS4401S

Are these the motors? https://www.amazon.com/Usongshine-nema-17-Stepper-Motor/dp/B07KW6B3ZX?th=1

Rated current is listed as 1500ma and you have 800ma set. It's generally recommended to use 70-85%. So 800 is a little low which could explain the lack of torque. Try 1200ma.

I've never seen anything like multiple motor failures like this before. I would expect a driver to go before a motor.

idmurp

@dc42 Permenant wires

@Phaedrux yes they are the motors, they have good holding torque at 800 to start with but that declines?

Im really confused as well, I cant find anything like it online either. But 3 failed motors...

dc42

@idmurp said in Duet WiFi and stepper motor Failrues:

@dc42 Permenant wires

One of the most common causes of weak motors is a bad crimp connection between the cable and the crimp pin in the Duet connector. Have you tried crimping a new connector on the leads of one of the failed motors?

idmurp

@dc42 No but I have swapped the motor for a new one, which worked fine. Then put the old one back on and that still had the low torque

idmurp

okay as it does not seem to be anything obvious. I know this has happened twice on Y so.

Printer is not earthed so earth it
I believe I can remap extruder 2 stepper to be the Y drive so do this.
Use a new fresh and tested cable
Use a new motor for Y drive.
Put a cooling fan on Y drive stepper
bump all of them up to 1200 ma

This gives me a essentially fresh start on the Y drive.

is there any chance it could be power supply related? I could swap the power supplies over and use the current heated bed supply for the board.

Then hope....

Any other suggestions?

Phaedrux

The only thing that seems unique to your setup is the dual power supply. can you post how you have it all wired up?

Lack of grounding is concerning. How is it grounded now?

idmurp

@Phaedrux said in Duet WiFi and stepper motor Failrues:

The only thing that seems unique to your setup is the dual power supply. can you post how you have it all wired up?

Lack of grounding is concerning. How is it grounded now?

240V to the 2 power supplies from a common plug.

First power supply, 30 amp on a 20 amp fuse powers the board

The second power supply just provides power to the mosfet that powers the bed, 30 amp fuse, it is not connected in any other way to the printer. I can run the printer with the second power supply disconnected alltogether if I dont want a heated bed.

Its a 400X400 printer, I need close to 30 amps just for the bed and had 2 30 amp power supplies to hand.

They do share a common earth bar, something I might change though I dont see how that would affect anything.

The power supplies are grounded, there is no ground on the board or printer itself. WIll ground the printer next

dc42

@idmurp said in Duet WiFi and stepper motor Failrues:

@dc42 No but I have swapped the motor for a new one, which worked fine. Then put the old one back on and that still had the low torque

If the cables are not detachable from the stepper motor, you must have used the new cable that came attached to it. That's why I suspect the crimp connections.

idmurp

@dc42 Cables came with it but not attatched, they are plugged into the stepper via a removable plug.

In other news this looks similar to my problem and was blamed on static build up...

https://forum.tiertime.com/t/extruder-driver-failing/545/4?fbclid=IwAR3OuNbYLukdrEG0CF6_pnnZ4PIy_lhVgHU2gJlcPu0u0v7wOYpwuTv9UTc

idmurp

In way of an update I have:

Replaced Y drive and succesfully tested other steppers
Repalced Y drive cable
Remapped Y drive to extruder 2
Grounded the printer

I am rerunning the setup and calibration today
Tomorrow Ill work from the same room as the printer and set a long print running, will give me 8-9 hours to monitor temps etc to see what happens

dc42

@idmurp said in Duet WiFi and stepper motor Failrues:

@dc42 Cables came with it but not attatched, they are plugged into the stepper via a removable plug.

In other news this looks similar to my problem and was blamed on static build up...

https://forum.tiertime.com/t/extruder-driver-failing/545/4?fbclid=IwAR3OuNbYLukdrEG0CF6_pnnZ4PIy_lhVgHU2gJlcPu0u0v7wOYpwuTv9UTc

Our wiki page https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors#Section_Connecting_stepper_motors includes this:

Note: it is highly recommended that the stepper motor casings be grounded, especially in belt-driven printers. Otherwise, motion of the belts causes static charge to build up, which eventually arcs over to the windings. If the motors are screwed to a metal frame, grounding the frame is sufficient.

idmurp

So I have done all of the above and have now done a reasonable amount of test prints without killing a further stepper....so far. Im suspecting it was static build up, but cant be sure

Have other problems now but all fixable.

Will update further if I do kill another stepper, but so far so good!