Different x-y offset; circle

[Vitali353 0]

While printing a circle the ultimaker makes different offsets in x and y. The  circle/zylinder usually messures 42mm (diameter). I got 42.08mm in x and 42.28 mm in y. Z is no problem. 

I tried different settings already but nothing solved the problem so far. I also did a maintanance of all axes and so on but it didn't help. I didn't do the axle alligment with thealigment tools ultimaker suggets, because if iprint a dice the offset in x and y are almost the same. 

So I figured it must be more of a programmatically problem instead of a mechanical one. Is there a way to programm a solution (maybe via g code) into cura like:

"If circle, do one step in x and one in y, instead of one in x and 2 in y..." 

 

My Printer:

Ultimaker S5 (model until 2020)

Version 6.5.1

Cura 4.9

 

 

Toleranz-Pruefkoerper_fein.STL

Edited September 20, 2021 by Vitali353

[gr5 2,172]

Some thoughts:

1) You can certainly go to the scale tool in Cura, then uncheck the "uniform scaling" and then increase X by 0.2 or decrease Y by 0.2.  This will probably work well for this part.  But other cylinders of different diameters or placed on different locations on your bed may need different scaling.

 

2) One common cause of this kind of error is that the pulleys, which have a hole drilled through the center - have that hole slightly away from center.  By maybe 0.2mm.  That means the pulley wobbles a bit and the head, if driven at a constant velocity will actually speed up and slow down a little each time the pulley rotates.  This error is less common on the UM3 and newer printers as Ultimaker no longer relies on 3rd parties to drill that center hole (I believe).  Or perhaps they inspect each pulley now.  Anyway the quality is much better than it was 7 years ago.

 

3) I looked at your part and the STL and I hope you rotate the part so the circle is flat on the bed!??  If not then that is your issue.

 

4) The problem may be caused by the print head wobbling a bit.  Push the print head towards the center of the printer and then gently push the nozzle left/right/forward/back.  Push almost hard enough for the steppers to move but not quite.  Does it move more in one direction versus another?  Sometimes the linear bearing inside the print head is a little loose.  The one with the rod that passes from front to rear of printer.