Extremely hot stepper motors on Ultimaker 3

[Kylellrc 0]

OK so I received my Ultimaker 3 in late may 2017 and i never updated the firmware around early September. After the update I noticd that the printer was significantly louder and thought it was normal. Just recently I checked how hot the steppers were because when I first got my ultimaker I remembered the steppers got warm on long 10+ hr prints. To my surprise the motors were too hot for comfort. I measured the temp with a multi-meter it it measured at 55 degrees Celsius. I have also been getting skipped steps which i'm starting to think is somewhat related to how hot the motors are getting.

[DidierKlein 729]

Hi and welcome,

 

First of all be aware that new versions of the firmware have been deployed since september, maybe it's worth updating?

 

From what i know stepper motors can reach 80°c and indeed when they heat up steps can be skipped, i'm not really aware of problems of overheating motors on the Ultimaker 3, are doing anything special?

 

Enclosure?

High Bed temperature?

Ambiant temp of the room?

[Kylellrc 0]

I always kept the printer in a cabinet and the only skipped steps that I experienced were that on only every time I did dual color prints on PLA (200c Nozzle, 50c Bed, Also single extruder prints came out fine) the first layer was always off by around 2-3 millimeters. The one time I printed something outside the cabinet it skipped really badly on the y axis. I'm currently doing a 10+hr print single color print so when its done I will update it and attempt another dual color print and see how it comes out.

 

 

[gr5 2,172]

Yes your Y axis clearly lost steps on one layer.

 

It's very unlikely the stepper itself is the problem - they can be at 80C and function fine.  The spec says something about 80C - I forget if that's max case temp, or max air temp.  Anyway the failure mode is to basically melt.  not skip steps.  Stepper drivers definitely can skip steps if they get too hot.  They are underneath your printer.

 

However this issue is VERY COMMON and 95% of the time the problem is that one of the pulleys needs to have it's set screw tightened.  Almost always one of the more difficult pulleys to get to.

 

There are 6 pulleys on the Y axis - 4 on the long belts and 2 on the short belt (I forget but in some cases two of the pulleys are merged into one so maybe 5 pulleys).  The ones on the short belt are usually the problem - the one on the motor most likely.  You can push the head around until you can see the set screw and get a long hex screwdriver into there.  Or worst case you have to remove the cover (only two screws need removing to remove the rear corner cover).

 

Tighten the hell out of these!  So tight that the tool is twisting.  So tight that if you use and hold an L shaped allen wrench by the short end your fingers hurt.  A lot.

 

If you don't believe me mark the motor shaft and pulley with a sharpie.  Same with the other pulley on the short belt.  See if it moves the next time you get lost Y steps.

[Kylellrc 0]

On 3/21/2018 at 8:36 AM, gr5 said:

Yes your Y axis clearly lost steps on one layer.

 

It's very unlikely the stepper itself is the problem - they can be at 80C and function fine.  The spec says something about 80C - I forget if that's max case temp, or max air temp.  Anyway the failure mode is to basically melt.  not skip steps.  Stepper drivers definitely can skip steps if they get too hot.  They are underneath your printer.

 

However this issue is VERY COMMON and 95% of the time the problem is that one of the pulleys needs to have it's set screw tightened.  Almost always one of the more difficult pulleys to get to.

 

There are 6 pulleys on the Y axis - 4 on the long belts and 2 on the short belt (I forget but in some cases two of the pulleys are merged into one so maybe 5 pulleys).  The ones on the short belt are usually the problem - the one on the motor most likely.  You can push the head around until you can see the set screw and get a long hex screwdriver into there.  Or worst case you have to remove the cover (only two screws need removing to remove the rear corner cover).

 

Tighten the hell out of these!  So tight that the tool is twisting.  So tight that if you use and hold an L shaped allen wrench by the short end your fingers hurt.  A lot.

 

If you don't believe me mark the motor shaft and pulley with a sharpie.  Same with the other pulley on the short belt.  See if it moves the next time you get lost Y steps.

After tightening the pulleys most of the skipping issues were gone except the one problem to where the 2nd layer and so on are offset by 2mm on the Y axis.

 

 

Edited March 28, 2018 by Kylellrc

[geert_2 557]

I don't know the UM3, so I am just guessing here...

 

Since those items are printed very close to the edge of the bed, could it be that the print head hits the back somewhere, or it hits something else? And this blocks it from going further, and thus causes it to skip steps?

 

If you print a little test model in the center of the bed, let's say a cube of 10mm x 10mm x 10mm, without anything else, does it also have this offset?

 

[Kylellrc 0]

On 3/28/2018 at 5:15 AM, geert_2 said:

I don't know the UM3, so I am just guessing here...

 

Since those items are printed very close to the edge of the bed, could it be that the print head hits the back somewhere, or it hits something else? And this blocks it from going further, and thus causes it to skip steps?

 

If you print a little test model in the center of the bed, let's say a cube of 10mm x 10mm x 10mm, without anything else, does it also have this offset?

 

I finally found out the problems were happening because the lift switch was not calibrated properly causing the print head to press on the switching bay way too hard. This thus caused the Y axis to skip.