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Ooozair

UM3 Stepper Motor Issue?

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Hey community,

 

My UM3's stepper motors are shaking and making an awful grinding sound. Sometimes the Y axis even travels the wrong direction.

 

The printer completed a print just fine, and when I began the next print, this problem began occurring. When the problem first occurred, it was only when the Y axis moved. After troubleshooting and watching it a few times, it started happening on both axis. Now, it consistently occurs on any axis movement (except Z, of course). Never had any similar problems thus far.

 

Here's a video of the issue. I took the print head off to eliminate the possibility that it's something to do with the linear bearings. 

(Sorry about the vertical camera)

 

 

In the video I'm running the "home head" command via the regular menus. I run it three times, and in the final try you can see the motor move the wrong direction too. 

 

What I know:

  • The limit switches are good (tested those by triggering them manually)
  • No mechanical contact on rods or blocks
  • Stock printer (no mods or changes, except some new print cores)
  • Belts are tight, no slipping.
  • Moving rods manually is smooth and easy. Shown in video. 
  • Firmware 4.3.2.20180308
  • Hardware type ID: 9066
  • The printer is kept relatively cool (it's in the company's server room which is kept nice and cold. Window and blinds stay closed always), but I can't verify the temperature of the stepper drivers on the board of course. 

 

I suspect the stepper drivers are bad. This sounds like what happens when I hook up a stepper motor incorrectly on a breadboard. But what would cause them to go bad? I'm not printing excessively fast or anything (typically ~80mm/s). Why did it start with one motor, but then occur on both after a few trial runs? 

 

Any ideas here? The printer is under warranty, and I don't want to do anything that will void the warranty (dunno if opening it up and inspecting the board is allowed or not). Anything I can do before I just send it back under warranty? Hoping to save some time by seeking suggestions. 

 

Thanks everyone. 

 

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This is a new issue for me.  I would check the power voltage with a volt meter (or even better with an oscilloscope) while the motors are moving.  I mean the only thing I can think of that is likely to affect both axes:

1) You messed with XY stepper current.

2) power supply.

3) You messed with jerk or acceleration settings.

4) You messed with max speed

5) Arduino clock speed is completely broken and running at 1/4 or slower rate.

 

I doubt you did 1,3 or 4 as those are very hard to change on the UM3 (need to ssh into the printer and edit json files).

 

I've heard this sound before when I was calibrating acceleration and max speed and I set either of them too fast.  Or if you set current too low or too high.  So if the 24V was actually at say 10V (while axes are moving) that would explain it.  Basically: white/larger PCB, or power supply, or firmware.

 

I'd say 70% chance it's the power brick.

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Have you checked all possible connection plugs for correct fit?
At best, remove every single accessible plug step by step and insert it correctly again.
Are all cables apparently intact?
Reset to factory settings already carried out at least once?

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Thank you all for the speedy replies! 

 

1 hour ago, gr5 said:

This is a new issue for me.  I would check the power voltage with a volt meter (or even better with an oscilloscope) while the motors are moving.  I mean the only thing I can think of that is likely to affect both axes:

1) You messed with XY stepper current.

2) power supply.

3) You messed with jerk or acceleration settings.

4) You messed with max speed

5) Arduino clock speed is completely broken and running at 1/4 or slower rate.

 

I doubt you did 1,3 or 4 as those are very hard to change on the UM3 (need to ssh into the printer and edit json files).

 

I've heard this sound before when I was calibrating acceleration and max speed and I set either of them too fast.  Or if you set current too low or too high.  So if the 24V was actually at say 10V (while axes are moving) that would explain it.  Basically: white/larger PCB, or power supply, or firmware.

 

I'd say 70% chance it's the power brick.

Where should I be probing to measure the appropriate voltage? Take the bottom board cover off and probe off the PCB/Arduino itself?

1,3,4) Nope, didn't mess with any of that. I have in the past specified jerk and acceleration settings for specific prints via Cura, but nothing within the hardware itself. 

2 and 5) Well, the Z axis motor and both bowden extrusion motors can spin at speed with no problem. Bed raise and lower works fine, as well as material load and unload. If it was the power supply or the MC clock, I imagine those other motors would also be affected?

 

 

1 hour ago, mnis said:

Have you checked all possible connection plugs for correct fit?
At best, remove every single accessible plug step by step and insert it correctly again.
Are all cables apparently intact?
Reset to factory settings already carried out at least once?

I felt around and re-firmed every connection I could see. The stepper motors seem to be connected with a small junction at the bottom, but light wiggling couldn't remove the cables and so I'm not sure if they're meant to be unplugged.

Without removing the board cover those are the only plugs I have access to. 

 

Cables all seem intact, no weird routing inconsistencies or pinch points. 

 

Just did a reset to factory settings, problem persists. 

EDIT: Wording

Edited by Ooozair
EDIT: Wording

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In order to reach all connection plugs and / or to make measurements, full access to the mainboard is required. I think it's not enough to measure only the no-load voltage on the power supply.

 

Unfortunately, I do not know the internal structure of the newer Ultimaker machines. But why go on fiddling? I would request a repair from Ultimaker if there is a valid warranty.

 

But if you can visit a local dealer with your machine, then I would ask to try a new power supply before the return is done.

 

Maybe there is also the possibility to get only a new motherboard, as long as you trust yourself to do the repair yourself. It is not so complicated to replace a motherboard. This saves valuable time and the somewhat complex process of shipping such large packages.

 

Edit:

If access to the MainBoard is not provided with a warranty seal in any specific way, then you should also be allowed to take a closer look at it without loss of warranty.

Edited by mnis

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I would contact either your reseller, or fbrc8 which covers USA.  If it's a large reseller like matterHackers they are pretty good but fbrc8 is even more knowledgable.  fbrc8 made your printer and they are experts.

 

If you are at all worried about voiding warranties, you simply need to get permission to remove covers before doing so.  But they won't know if you removed the cover of the larger board without you telling them.

 

Good point about Z and E axes - but the X and Y axes may be set up to run closer to their limits of acceleration and velocity and may be more likely to miss steps (that's what this is - missing steps - the steps don't have enough power to move the X and Y axes).

 

Oh! that gives me an idea.  Maybe you have high friction (due several possible things including no oil).  With power off you should be able to push the head with just one finger on each end of one of the rods that goes through the head.  Try adding some light oil - sewing machine oil or 3-in-one oil or any light mineral oil (not vegetable oil which will go rancid, not wd-40, baby oil will work).  Put very little oil on - one drop on each of the 6 rods in the gantry.  Push the head around to spread the oil.

 

High friction can be caused by too much belt tension (unlikely but I've seen it) also.  

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Hey everyone! Sorry about the seemingly late replies on my part, since I'm a new forum user the mods have to accept all my posts manually. 

 

Good news- got it fixed! But, still not sure exactly what was causing it. Here's what I did.

 

Under the guidance of Ultimaker US Support (thanks Spencer!) I got some help. Turns out I wasn't under warranty anyways, haha. I took a look at the white main board. Nothing looked amiss. All the cables were seated properly, all the locking clips were engaged. No physical damage on the board or anything.

 

Before the next test, Support did have me unplug the power brick from the machine and the wall, and see how long the LED stayed on. It remained on for well over a full minute. 

 

I had the idea of plugging the X/Y motors into the Z port, and running "Lower Bed" to see if the motors themselves worked properly when plugged into the Z port. The plugs were tough to un-plug, they were definitely seated properly to begin with.  When in the Z port, both X and Y stepper motors were driven like normal. So I thought it could be the X and Y drivers.


Then, I plugged the Z motor into the X then Y port, and used "Home Head" to see if the Z motor would be driven smoothly. It was! So, it wasn't the motors themselves, nor was it the drivers.

 

I went ahead and plugged all the motors back into the correct ports, and... it worked? No jitters, no stutters, everything moving smooth. A bit confused here, nothing fundamentally changed, but the problem disappeared as quick as it appeared in the first place. I'll keep an eye on the machine during the next few test prints.

 

So technically, all the steps I did from problem to solution were: Factory Reset >> Power Supply LED Test >> Unplug all motors >> Drive X motor with Z port>> Drive Y motor with Z port  >> Drive Z motor with X port >> Drive Z motor with Y port >> Return all motors to correct ports >> Motors now move smoothly. Tested using Home Head and Manual Bed Leveling

 

Thanks for all the help guys, this community has excellent support. 

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My first suspicion, the power brick, is now my latest suspicion.  It will probably get gradually worse and power cycling it may help.  Or it may be a fluke where the cpu in that power brick got confused about what voltage it was supposed to be putting out and power cycling the brick helped.

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14 minutes ago, gr5 said:

My first suspicion, the power brick, is now my latest suspicion.  It will probably get gradually worse and power cycling it may help.  Or it may be a fluke where the cpu in that power brick got confused about what voltage it was supposed to be putting out and power cycling the brick helped.

 

I'm sharing the same suspicion, it's the only thing I did that really changed any states within the system. If it happens again, I'll cycle the brick first and see if that helps. 

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