print head bashing repeatedly when traveling to home position - SOLVED

[bjammmin 0]

Lately my Ultimaker 2 print head has started behaving oddly when starting or finishing a print. When it tries to slide over to the home position, it starts bashing against some sort of physical or software stop and makes a really loud and annoying noise very similar to machine gun fire (*bam bam bam bam bam bam bam*). It probably does this repeated hitting for 2-4 seconds before it stops and then just carries on with the job. I can't imagine this is good for the printer - has anyone else experienced this?

 

[nallath 1,124]

Sounds like one of your end stops is broken.

 

[gr5 2,240]

It won't damage your printer but it turns your repeatability to hell. Definitely fix this.

The problem, as Nallath says, is you aren't triggering one of the endstops. With power off push the head around and into that corner (one axis at a time) and listen for the faint click when the endstop is triggered. See if one of the axes isn't triggering. It could be one of your thin metal rods that pass through the head isn't sticking out far enough on the side to hit the endstop. It could be your endstop moved. It could be the fan shroud is no longer symmetrical and that is hitting. It could be lots of minor mechanical things.

If you can't figure out what changed you could just bend the metal arm of the endstop so that it gets triggered sooner.

 

[bjammmin 0]

Thanks for the quick answers. One of the metal endstop triggers was bent out of the way. This seems quite odd, since this area has never been handled/adjusted/disassembled, etc. Seems like somehow it happened by itself. Bent the piece of metal back to (almost) straight, and now the microswitch is triggering properly.

I noticed my motors now sound a bit different when moving the print head. I don't see any functional issues in the print, but they just sound different when being actuated. Could the endstop issue have caused any permanent damage?

 

[nallath 1,124]

Not likely, but it is possible. It could also be that the axis are not quite straight anymore, which can cause a different sound. You could try to lubricate the axis by applying a bit of (sewing) machine oil.

 

[gr5 2,240]

This happened to my UM2 almost exactly a year ago and it's been working fine since. The steppers are strong but weak enough so that the machine shouldn't be damaged. The same goes for UM Original. We are talking about X,Y axes here. I can't speak for the Z axis.