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Circles are not fully round

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Hello all,

I know this seems to be a common fault with Ultimaker Original machines, but I seem to have tried all remedies suggested and it still refuses to work!

I have:

Put Belt tensioners on Long belts

Tightened the short belts by pushing down the motor

Tightened the cross axis rod block (Thinner rods which mount to the print head)

Made sure hot end doesn't wobble/move freely

Checked extrusion rates

Tightened all the pulleys to the rods

Made sure the cross rods are square

The errors seem to be happening at 45* from the X and Y, so it leads me to think it's a belt (slack) issue, but with tightening every single belt, I'm at a loss!

I hope someone might have some suggestions?




Bottom right circle seems to show the defect clearly as it has gaps in the walls at half one and half seven. It should be solid like the other quarters.


Edited by Guest

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While knowing you said you tensioned the short belts, I am still inclined to think the problem lies with your short belts. Do you have a photo of some reference on how tight they are? Perhaps pushing against it with your finger?

And can you move your printhead around with just 1 finger pushing against your print head? How freely can it move / how much resistance do you feel?


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Hi SandervG,

I have tightened the short belts very tightly indeed.

There is hardly any flex in them at all.

There seems to be moderate resistance, but this feels like it's coming from the belt tension.

Could they be too tight?

I have also double checked my alignment, still all good!



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