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Printer head has a mind of it's own!

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Hi all,

After assembling my ultimaker, when I start a print, it will print fine for maybe 4 or 5 layers. But then the printer head will go off course and print at random. I have no idea what is wrong with it. Anyone have any ideas? I'm running the newest version of Cura on mac. Thanks!

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maybe one of the following:

- EMI interference -> one or more endstop cables are passing too near to a steppermotor cable.

Just avoid this and have all wires properly twisted

- belts not tight enough. should hear skipping sound sometimes if this is the case.

Get a upgradepart from thingiverse..

Check the modifications Board here. there are some awesome essential addons for ultimakers

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Can you move the head easy by hand when the machine is off? You should be able to move it quite easy, if this is not the case then your axes might not be square.

Else, check belt tension as yzorg suggests.

(EMI on the endstops is very rare, and I've only seen it happen with a teslacoil)

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i got another tipp on this..

if i print with Printspeed 50mm/s (Cura)

my machine tends to behave very strange.. printing first layer fine and next layer 5mm away then prograssing to print there sometimes but also making layers piles all over the place.

after setting that Printspeed up to 70mm/s

No issues anymore.

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Arch1tect - I'd definitely check that your belts are tight, and also that all the pulleys are done up tightly, and aren't slipping. As Daid noted - when the printer is powered off, can you move the head in x and y directions fairly easily, by pressing gently on the sliding blocks?

The video was a bit hard to see the detailed print quality, but I noticed that even the base layers where it was printing 'right' looked rather scrappy, and the left and right extremities of your object were getting turned into flats (I presume they are supposed to be curved). That also sounds like it could be a belt tightness issue to me.

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I dont think this has anything to do with belt tightness, and tightening them more will probably make your problem worse (as the tighter they are, the more friction there is, so the motors are working harder).

Because the circles are clearly not circular even at very low printing speeds, its definite that one or more

of the grub screws in either the shafts or on the ends of the motors are not very tight.

Just methodically re-tighten every single pulley and it will be fixed. Typical culprits are the ones on the

end of the motors, because they are hard to get to, people ignore them.

If it was a belt slipping you can only be innacurate by one tooth pitch. So you will find in that case that the basic shape is correct, but just then jumps a few mm in one direction. You have what appears to me to be a much more gradual and fluid change in orientation.

After tightening all grub screws, make sure you apply thin machine oil (bicycle chain oil, sewing machine oil) to the rods. If they are left to go dry, or you put grease on them, the friction can be enough to overcome the grub screws.

Its usually a motor pulley screw, because that pulley is doing 2x the work of all other pulley.

If it was a belt you would also hear a very audible BOINK ! sound when it skips over the teeth.


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