X-axis and heat-bed horizontal lines not quite parallel
 
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X-axis and heat-bed horizontal lines not quite parallel  

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Daryl
(@daryl-2)
Trusted Member
X-axis and heat-bed horizontal lines not quite parallel

Just finished building Prusa Mini #2 last night and it works well.  I did note visually that the x-axis isn't quite parallel with the horizontal lines on the heat-bed (see pic about 1mm end to end skew).  Chat line said not to worry about it.  Others seeing this issue?  Will print some test patterns and see if it is affecting prints.  Haven't found an "official" alignment procedure for this.  (I'm also surprised the instructions don't have builder check X to Z calibration - guess they hope auto bed leveling will care for any skew in that axis).

PS - Kit was delivered May 23rd, they switched from sampling "Galaxy Black" to "Gentleman's Grey", an interesting dark blue/green/grey color.

Posted : 28/05/2021 6:29 pm
matthewlloyd
(@matthewlloyd)
Active Member
RE: X-axis and heat-bed horizontal lines not quite parallel

This is XY skew. I have a similar amount and in the same direction on my 2-day old Mini+ (about 1% error). Can't correct it in firmware because M852 is disabled in the official firmware (see https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/385).

Some more notes on this and ways to fix it using shims and other mechanical methods:

https://forum.prusaprinters.org/forum/hardware-firmware-and-software-help/oh-no-were-skewed-prusa-mini-edition/

Posted : 29/05/2021 1:49 am
Daryl
(@daryl-2)
Trusted Member
Topic starter answered:
RE: X-axis and heat-bed horizontal lines not quite parallel

I printed a calibration square and the diagonal measurements are definitely different.  Will try shims, thanks.

Posted : 29/05/2021 11:51 pm
Daryl
(@daryl-2)
Trusted Member
Topic starter answered:
RE: X-axis and heat-bed horizontal lines not quite parallel

Update:  Mini #1 (factory built) is off by 1.6mm when comparing diagonal lengths of test square.  Mini #2 (kit) is off by 0.7mm.  Dialing them in now with XY shims suggested above.  Why bother?  Building some precision parts and minimizing skew is important.

Posted : 01/06/2021 3:32 pm
matthewlloyd
(@matthewlloyd)
Active Member
RE: X-axis and heat-bed horizontal lines not quite parallel

I just did mine. You don't really need shims. Just loosen the three screws that hold the Z axis to the Y axis, reposition the axis carefully by eye, then tighten just the one on the top of the extrusion to set the position. The other two can be tightened but very loosely so as not to change the position. It's not a perfect solution but good enough if you don't move your Mini+ much.

This calibration cube is really great, prints fast and uses very little plastic, and gives you all the measurements you need: https://www.thingiverse.com/thing:4611756

Posted : 01/06/2021 3:44 pm
Daryl
(@daryl-2)
Trusted Member
Topic starter answered:
RE: X-axis and heat-bed horizontal lines not quite parallel

Just finished getting X and Y properly perpendicular (minimal skew).  Both my fully assembled Prusa Mini+ (Nov 2020) and a new kit Prusa Mini+ (May 2021) ended up requiring a 1.6mm shim.  I like using the shims as it allows the arm to be tightened as designed (almost).  Printing all day, every day I'm not sure I would want just one screw holding the entire XZ assembly.  Thanks @matthewlloyd for the cube suggestion.

Posted : 02/06/2021 11:29 pm
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