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Calibration

Posted: Wed Oct 22, 2014 6:35 am
by FaVo
Hi all,

I have done the assembly of my Shapeoko 2 custom build. Now it comes to calibration and trimming. My first test looks like this:

Image

As you can see the beginning and endig of each line is shifted. What can cause this behavior?

Thanks!

Re: Calibration

Posted: Wed Oct 22, 2014 11:49 am
by cvoinescu
Anything being loose can cause that. Even the fact that you use a ballpoint pen and the lead can move inside the pen case. But it could be the pen not attached firmly to the Z carriage, lose V-wheels, a floppy belt, the set screw for a belt pulley not being tight, and a number of other things.

Re: Calibration

Posted: Thu Dec 04, 2014 4:54 am
by corim123
To me the fact that the error happens in roughly the same portion of the plane each time suggests it is something to do with a loose portion of the x or y-axis. It just seems to be a non-random error from one type of motion in particular.

Re: Calibration

Posted: Thu Dec 04, 2014 11:30 am
by WillAdams

Re: Calibration

Posted: Thu Dec 04, 2014 12:22 pm
by dougal
The misalignment is always at the start and end of a line. On the h i l and other i these happen to line up vertically. So first thing to check is that your pulleys aren't slipping. Might need a flat made on the stepper shaft.

Re: Calibration

Posted: Thu Dec 04, 2014 1:18 pm
by Gadgetman!
How much is it slipping?

This is TinyG, right?

What is the $mt variable set to?

Re: Calibration

Posted: Sat Dec 06, 2014 1:41 am
by oniontalker
Z0 or "depth of cut" might be a little to Z-. The pen might be drifting and when it lifts, it mostly goes back to a stable position.
I'd try with a sharpie or some sort of felt tipped instrument and reduce the, "depth of cut", to rule that out.

Re: Calibration

Posted: Tue Dec 16, 2014 2:11 pm
by FaVo
Sorry for my late answer.... the most alignment problem wasn't a real problem but flexing of the pen... like many many other already had.
Even if the pen and the mounting of the pen looks stiff... IT ISN'T.

Adding an endmill and cutting some test patterns into wood looks way better than drawing with a pen.

That is my experience (and as I can read in the forum, many other did make this experience as well).