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Circle not round

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Posted (edited) · Circle not round


I am not sure if this is a hardware or a software problem.

When I print a test circle with a wall thickness of 0.8mm then, it is not everywhere that the two walls touch each other.

I have tightened all belts and calibrated parallelism on small rods

Printer: Ulitmaker orginal +

Design tool: 123D Design

Slicing software: Cura

Cura settinge see pic.


thank you in advance



Edited by Guest
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    Posted (edited) · Circle not round

    The Cura picture is missing somehow... ;)

    Do the two walls not touch each other all around the circle or just in two diagonal quadrants?

    Edited by Guest
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    Posted · Circle not round

    On S3D you can 'overload' the thick walls to push more filament if the 3d design isn't 0.8 wall thickness. Cura will try it's best to fill the gap if the design isn't of that thickness. But we can't see that without the cura layer img.

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    Posted · Circle not round

    It could be mild underextrusion or it could be backlash.

    Mild underextrusion would be expected if you exceed the settings in this table:

    Here are top recommended speeds for UMO, UM2 with .2mm layers (twice as fast for .1mm layers):

    20mm/sec at 200C

    30mm/sec at 210C

    40mm/sec at 225C

    50mm/sec at 240C

    Backlash on UMO is most often either loose *short* belts (not the long ones) so slide those motors down tight, or endcaps too tight - push the head around - if resistance is too high then that will cause backlash. Overly high resistance is usually because the long belts are too tight or even more likely one or more endcaps are causing excessive friction. You only have to loosen one endcap per rod (only loosen 4 encaps and only a small amount). Also add a drop of oil to the 6 horizontal rods (yes I said six, not four).

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