Warm idler motor and hiss (extruder motor) while idle
Historically I print enough that I almost never turn the printer off, but sometimes it will end up idle for a few hours or days. Since adding the MMU I've noticed 2 things when it sits idle.
The first is that no matter how long it is idle, the idler motor is always warm. I've confirmed that it is not moving at all, but it's warm. I just checked it actually (single filament print has been running for a bit over 3 hours) and it's pretty much the same temp as when it's idle (which makes sense as it shouldn't be doing anything). The extruder and selector motors are cool to the touch and the X, Y, and Z motors on the printer itself are also cooler than the idler motor.
The other thing is that when the printer is idle there is a "hiss" coming from it now. I THINK it is coming from the extruder motor, but the selector motor (doubtful) and power supply (maybe related to the idler motor?) are also possibilities.
Anyone else experience these issues? Normal or should I see what support has to say?
RE: Warm idler motor and hiss (extruder motor) while idle
When a motor is in 'hold' mode, holding a particular position, rather than in 'idle' mode, it will hiss and will be warm. The wamth comes from a current flowing through the motor, holding it firmly in the position. The hiss comes from magnetostriction. Magnetostriction is a phenomenon that casues materials to constrict when exposed to a magnetic field. When the TMC2130 controller manages the holding current, it relies on the inductance of the motor and there is a certain fluctuation of the current in the motor. That causes a fluctuating magnetic field, a fluctuating size of the magnetic elements and thus production of sound. And because most of it is above audible frequency, the ear only hears some stray harmonics - a hiss. The same hiss then also comes from the PSU, because the PSU load is similarly (even more so) uneven and thus the coils in the PSU are exposed to a similar magnetostriction effect and also produce a sound.
RE: Warm idler motor and hiss (extruder motor) while idle
Yeah. Tim's right. I guess "that's normal/expected" is too easy 😀
I can understand holding the position while the printer is running (or paused mid print), but it'd be nice if they let it go when the printer isn't processing a job. They can always do a calibration reset prior to starting a new job if needed.
RE: Warm idler motor and hiss (extruder motor) while idle
You can go into the settings menu and there is an option to turn off all stepper drivers. This stops the hiss for me.
RE: Warm idler motor and hiss (extruder motor) while idle
I'll give that a shot after the current print and see if it helps. Thanks for the idea.
RE: Warm idler motor and hiss (extruder motor) while idle
You can go into the settings menu and there is an option to turn off all stepper drivers. This stops the hiss for me.
I don't know if the motor would have cooled as I didn't give it time, but disabling the steppers didn't stop the hissing so I suspect that the motor wouldn't have cooled.
RE: Warm idler motor and hiss (extruder motor) while idle
Yeah. Tim's right. I guess "that's normal/expected" is too easy 😀
I can understand holding the position while the printer is running (or paused mid print), but it'd be nice if they let it go when the printer isn't processing a job. They can always do a calibration reset prior to starting a new job if needed.
For whatever reason I don't see Tim's post, but yes, I agree that the printer should turn the steppers off when not printing, if it can re-home them at the beginning of a new print. I currently don't have any experience with the MMU2S, so I can't say whether that's feasible.
RE: Warm idler motor and hiss (extruder motor) while idle
Yeah. Tim's right. I guess "that's normal/expected" is too easy 😀
I can understand holding the position while the printer is running (or paused mid print), but it'd be nice if they let it go when the printer isn't processing a job. They can always do a calibration reset prior to starting a new job if needed.
For whatever reason I don't see Tim's post, but yes, I agree that the printer should turn the steppers off when not printing, if it can re-home them at the beginning of a new print. I currently don't have any experience with the MMU2S, so I can't say whether that's feasible.
I meant his past commentary on your loquacious technical answers 😉 😀
RE: Warm idler motor and hiss (extruder motor) while idle
For whatever reason I don't see Tim's post,
I meant his past commentary on your loquacious technical answers 😉 😀
Ah yes. He is definitely right on that. 😀
RE: Warm idler motor and hiss (extruder motor) while idle
Finally got a chance to disable the steppers and leave it idle over night. As expected it was still hissing and warm this morning.
I'll reach out to support about it at some point.
RE: Warm idler motor and hiss (extruder motor) while idle
@gnat
I recently installed a mmu2s and apart from the obvious normal starting problems the motors do not switch off and become warm. Any answer from support?
RE: Warm idler motor and hiss (extruder motor) while idle
Reading this post has helped me so much, thanks.
I'm not sure how the Prusa printers work, but for my Voron, I went into my printer.cfg and added `M84` to my `print_end` macro. All motors turn off, including the extruder. No more hissing, no more heat.
THANK YOU!