Offsets when printing circular objects

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YouraT
Posts: 7
Joined: Fri Aug 11, 2017 3:37 am

Offsets when printing circular objects

Post by YouraT » Thu Sep 21, 2017 4:24 pm

I'm having trouble, with my i3/M201when printing objects with circular features - I don't get this with objects that are made of only straight line sections.

Calibration cubes and things like that, for example:
https://www.thingiverse.com/thing:45225
print very well - within expected limits in any case.

As an experiment in dual colour printing, I gave this item a go:

https://www.thingiverse.com/thing:1753813

and shortly after starting the second layer, one of the perimeter passes went wrong thus:
BatMan.JPG
BatMan.JPG (330.18 KiB) Viewed 7489 times
The diameter of the coaster is 100mm, and once the offset has happened, it's around 25mm out.

It's almost as if the Y (it's always a Y problem) skips steps after a while - it certainly makes a strange noise whilst this is happening - I've tried turning the current up to the Y stepper a little (800mV now) but that hasn't helped. The Y carriage (table) motion is smooth throughout its range.

Also this fan cowl:
https://www.thingiverse.com/thing:1844327
fails in a very similar manner after a layer or so, as does pretty well anything with circular features. It *seems*, although it's hard to track down to be sure, that the larger the diameter of the circular feature, the more likely it is to go wrong, or the more wrong it goes, when it does....

Any pointers/thoughts/ideas ? Straight lines are getting boring !

Thanks, Youra.

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William
Site Admin
Posts: 6340
Joined: Tue Jun 07, 2016 9:38 am

Re: Offsets when printing circular objects

Post by William » Tue Sep 26, 2017 5:17 pm

Firstly, I think you have to adjust the A4988 voltage of Y axis to 1v.
Secondly, maybe the A4988 is not OK. And you can swap the A4988 of X-axis with the A4988 of y-axis and check.
Thirdly, you'd better provide a video about it.
-Keep your mind and try to test it. :)
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-You can ask me the questions and I will kindly reply.
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