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Looking for good fix for XY skew  

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Ren
 Ren
(@ren)
Eminent Member
Looking for good fix for XY skew

Hi, I experience some XY skew on my mini. Do we have some better solution to this than brute force method of forcing shims between the frame and the electronics box?

Long version: I print happily for months now, but recently I started making more device cases and boxes and stuff like that, which really depends on right angles. Obviously, when there is a skew in XY and you print the box in open position, the skew effectively doubles when you try to close it and that easily makes it unusable. I was looking around, and found @nizmox' github which originaly started here on forums. My exact case is that X arm is not perpendicular to Y when looking from top. Now, I tried the shim method, and that works sufficiently. Seeing my declension is quite large (~3mm along the whole length of the X rods), instead of printing bazillion of them I printed one 2mm piece and just slide it along the interstice until I saw the smooth rods of X align with the dotted lines on the heat bed (yes, directly the heat bed, not a sheet, careful about that if you're going to follow this method!). So I (surprisingly quickly) achieved perfect squareness which is nice but the method feels to be crude, almost brute somehow. The side of the printed box is bent, gap in my case is quite large so I am not sure about good stability along Z, long term stability of the solution, etc. Would be nice to have some more elegant method but it seems the anchoring of the Z rods in the electronic box do not allow much tolerance to tune it here...I believe there are some plugins for Octoprint to compensate such errors but I did not use Octo yet...Ideas?

Posted : 03/12/2021 11:50 pm
BogdanH
(@bogdanh)
Honorable Member
RE: Looking for good fix for XY skew

As you realized, adjusting Mini's geometry is quite problematic. It comes down to tightening bolts more or less at specific locations, which isn't really an engineering approach. Ok, I will say it loud: Mini's frame design is not some masterpiece.

What to do? Well, there isn't much  you can do (except shims you mentioned). I managed to adjust geometry to acceptable degree without shims. But knowing how fragile these adjustments are, I try not to move Mini much and when I do, I do that quite carefully.
Anyway, geometry issues can be reason enough to upgrade to well designed BEAR frame. Because other than that, is Mini a very good printer.

[Mini+] [MK3S+BEAR]

Posted : 04/12/2021 8:30 am
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