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US3 breaking to not change extruders


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Posted · US3 breaking to not change extruders

So our Ultimaker S3 extended seems to have decided that the switch for changing the extruder head is further back than it actually is while printing, I say while printing because I can run a switch calibration test and it works fine but when it tries to change materials during a print it goes to the right and then back towards the switch and then it just keeps trying to go back until I can hear the motor grinding. Then when it tries to move to print (some times I'll move the lever myself to see where it prints) it doesn't print anywhere near the calibrated location (I've run the X & Y calibration multiple times as well. 

We're running the latest firm ware, so no issues there. I saw one other forum post where someone had these same issues and I did try all their fixes with no luck I'll link that 



Any advice would be appricaited, I'm pulling my hair out at this point 

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    Posted · US3 breaking to not change extruders

    cant see from your pictures but usually that points to a damaged limit switch
    (bent arm, etc)

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    Posted · US3 breaking to not change extruders
    16 minutes ago, Dustin said:

    cant see from your pictures but usually that points to a damaged limit switch
    (bent arm, etc)

    I thought that as well, but it seems to have no issue homing or preforming a switch test.

    Is there a separate limit switch it uses during printing or something different that would make the one that usually works not work in this case?

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    Posted · US3 breaking to not change extruders

    if the arm is bent.. it can still pass those tests.. 
    pictures are needed for the x and y limit switches

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    Posted · US3 breaking to not change extruders
    On 6/27/2024 at 11:25 AM, Dustin said:

    if the arm is bent.. it can still pass those tests.. 
    pictures are needed for the x and y limit switches

    Hey, sorry for the long wait for these. We got busy with other projects and put the Ultimaker 3 on hold. Here are the photos of the limit switches, no visible bends or any defects in them 

    20240627_125059.jpg

    20240627_124450.jpg

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    Posted · US3 breaking to not change extruders
    On 6/27/2024 at 11:25 AM, Dustin said:

    if the arm is bent.. it can still pass those tests.. 
    pictures are needed for the x and y limit switches

    any advice on this? 

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    Posted · US3 breaking to not change extruders

    You are posting in too many different topics.  It's confusing.  Maybe we can stick to this topic?  It's one you started.

     

    losing steps

     

    So I notice now in the photos above that it looks like you are losing steps. Do you see what I mean?  The problem is it looks like both axes might be losing steps?  This is very rare - usually only one or the other will lose steps.  For example the white and black patterns seem to have slid funny?  And the orange and "whitish" stuff underneath seems to have slid?  Or did the glass get moved in between?  Or is that normal?

     

    Also in the photos I don't think you have the S3.  You have the Ultimaker 3 (extended).  The 3 and the S3 are actually quite a bit different.  But that's not relevant to your issues.

     

    So sometimes the X or Y axis won't move as much as it's supposed to.  We call that "losing steps" because the stepper motor was told to step and didn't.  Often due to friction on older printers.  There are other causes but I'd check friction first.

     

    limit switches

     

    I know you said they looked okay.  Do they sound okay?

     

    Actually - first I'd check that the limit switches click.  So push the print head to the left edge and listen for the limit switch to click.   That's the X limit switch.

     

    Then push the head to the back and listen for the Y limit switch to click.  Sometimes the rod doesn't reach that switch the rod slid to the right too much sometime in the past.  The rod itself - the X rod is supposed to extend beyond the left sliding block.

     

    friction

     

    push the print head around.  Notice friction.  X and Y should be the same.  You might need to clean the rods or something.  You should be able to push the head with jsut 2 fingers - one from each hand - left hand's finger touching left block, right hand's finger touching right block.  You should be able to move the head without the printer sliding around on the table.

     

    If friction is too high then the printer can lose steps.

     

     

    The more you reply to posts like this, the more motivated people will be to help.  So please straighten me out and help me figure out the right path to follow for your printer.

     

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    Posted · US3 breaking to not change extruders

    In this picture you took the rod looks bent.  Is it just the camera lens or is it really visibly bent?  A bent rod could add a lot of friction and explain lost steps.  Or maybe you don't have any lost steps and there's another explanation for those double images.

     

     

    Screenshot from 2024-07-17 08-20-59.png

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    Posted · US3 breaking to not change extruders
    1 hour ago, gr5 said:

    In this picture you took the rod looks bent.  Is it just the camera lens or is it really visibly bent?  A bent rod could add a lot of friction and explain lost steps.  Or maybe you don't have any lost steps and there's another explanation for those double images.

     

     

    Screenshot from 2024-07-17 08-20-59.png

    Do you mean the limit switch or the rod, neither are bent ? I can tell you its definitely not the limit switches as it'll home just fine with no issue and every other step it needs to reach them it clicks them with no issue. 

    I keep getting suggested that its missing steps but it confuses me how it can be going too far when missing motor steps, the print head seems to just try and push its self past the boundary of the printer into the far right back corner and then tries to switch misses (I've done the switch calibration a dozen times with no issue it seems to only be when its trying to print does it have this issue or bed leveling) 

    Friction wise I have no issue moving the head around with one finger on each side, the rods have been good and lubricated for some time 

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    Posted · US3 breaking to not change extruders

    If it misses steps when it's moving to the front of the printer, then when it tries to move to the back it will go too far.

     

    So as the electronics send the command to move a step towards the front, then a millisecond later move another step to the front, what happens is the stepper is stuck and no movement happens.

     

    Sometimes it misses only 1 step per minute and the printed part has a slight tilt to it as I think there are about 80 steps/mm if I remember right.

     

    Sometimes it misses hundreds or thousands of steps in just a few seconds when there is a fast acceleration.

     

    If it's missing steps you should see sudden or gradual shifts.  Also it should happen in both axes.

     

    Another cause of missed steps is if the locking screw comes loose.  There is a tiny screw in every pulley and that screw needs to be tight as hell.  So tight that the allen wrench or hex driver is actually twisting a little.  So tight that it seems like you might snap the wrench.  Unfortunately, it's almost always the screw on the pulley that is actually on the stepper as that one has the most torque.

     

    This issue is pretty rare on the UM3 as they tighten the hell out of these at the factory but your printer looks quite old.  I've never had to tighten these on my UM3 and S5 but I *have* had to tighten them on my old "UM Original" and the problem can occur on any printer really.

     

    It's important to know which of the two axes (X and Y) are slipping as if only 1 axis is slipping then you know that it's losing steps somewhere.  If both axes are slipping at the "same" time then something weird is going on - maybe the power supply is weak and the 24V is actually more like 15V under load.  This seems unlikely but there are other possibilities.

     

    I guess I'd love for you to do a single filament print where there are no nozzle changes and let me know if it tilts or has sudden layer position changes in X or Y.

     

    By the way I've experienced those horrible noises where the print head tries to go farther than it can.  It sounds like the printer will destroy itself but it is tough and will be fine.

     

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