Print Circle

Tanuki44

Hello,
First, thanks for your great job.

I have a home made printer and works fine at 99%, (driver A4988)

My problem is only when I print a circular form (see photo)

I think that the problem is with axe Y when direction change.
I haven't lost step.
I have tested the backlash compensation but no resolve the problem and the circle is more distorted.
Have you a idea ?

Thanks

Repetier

Is the image with backlash enabled? Looks like it with the extended parallel segment at turn point. Enabling backlash extends object size as it adds a extra move on direction change. So assuming this is with BS enabled, your problem is a different but we have no image of that problem.

Also make sure not to test first layer. Here different bed height can make the first layer wider or narrower, only the following layer are relevant to distortion.

What other reason for distortion is steps per mm being wrong. Especially if belt is under high tension, it could be different from theoretical value computed from belt pitch and pulley tooth. Not much but measurable on larger objects. In that case the error is proportional, so make 3 rectangular qubes, e.g. 2cm, 4cm and 6cm and see if they grow the same percentage.

Tanuki44

I activated the backlash in the Arduino editor and assigned a value to Y,
but last night, I found that the value in the EEPROM remained at 0.
I modified this value and now it's OK.
Thank you for taking the time to answer me.