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Circles are not fully round

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Posted (edited) · Circles are not fully round

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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    Posted · Circles are not fully round


    I don`t have a Ultimaker, but had the same exact problem on my own printer.


    You have a perpendicular, or parallel, axle (x,y,z) problem, they are not at exact 90 degree, or parallel, from each other.


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    Posted · Circles are not fully round

    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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    Posted · Circles are not fully round

    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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    Posted · Circles are not fully round

    Could be a loose pulley on a motor/shaft!

    I put marks on mine with a permanent marker, a stripe that goes from shaft to the pulley. A quick look will show if anything moved.

    // Per.

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    Posted · Circles are not fully round


    I have simmelair problems

    Wonderd if and how you solved the problem

    Wr Henl

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