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XZ Gantry not square to Y  

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awoodbridge
(@awoodbridge)
Active Member
XZ Gantry not square to Y

I assembled my printer. It prints well, except that the the X and Y are not perfectly square, they are slightly off, about 1 mm shifted.

I verified this by taking off the build plate and use the grid on the heated bed, it doesn't follow the lines left to right.

Posted : 05/05/2020 6:31 pm
steve
(@steve-13)
Trusted Member
RE: XZ Gantry not square to Y

Well....it's not very clear how you're measuring this or even if you're measuring it properly. But 1) even if the plate is a bit out of square why do you care if it's printing properly? 2) The X/Y will always - ALWAYS be out of square to some tolerance (every measurement has a tolerance), which is why the MINI takes the 12 measurement points and corrects for it. PRUSA printers correct for skew (up to some threshold)  automatically.

So it sounds like you've measured something that is to be expected, and it's not causing a printing problem....what issue are you having?

Posted : 13/05/2020 1:37 am
awoodbridge
(@awoodbridge)
Active Member
Topic starter answered:
RE: XZ Gantry not square to Y

If I print this file on my Prusa i3 mk3 this rectangle has square corners. If I print it on my mini it doesn't.

Posted : 13/05/2020 2:13 am
awoodbridge
(@awoodbridge)
Active Member
Topic starter answered:
RE: XZ Gantry not square to Y

If I print this file on my Prusa i3 mk3 this rectangle has square corners. If I print it on my mini it doesn't.

Posted : 13/05/2020 2:13 am
steve
(@steve-13)
Trusted Member
RE: XZ Gantry not square to Y

Ah - thanks for the clarification and picture, it was not clear from your initial description.

So...just to clarify the issue with some questions:

  1. Are all 4 corners out of square?
  2. Is it printing a Parallelogram? (Where two adjacent corners are shifted together in X or Y from the opposite adjacent corners).
  3. Is it printing a Trapezoid? (Only two sides are parallel).
  4. Are the lengths of the X sides the same as the Y sides?

Also:

Are you running the latest firmware and using the latest slicer?

Have you done a first-layer calibration again?

Did you see the "Loose X or Y Axis Belts" section (Pg 43) in the Mini handbook?

Posted : 13/05/2020 1:38 pm
bobc
 bobc
(@bobc)
Reputable Member
RE: XZ Gantry not square to Y

It seems a few people have this issue, related thread is https://forum.prusa3d.com/forum/assembly-and-first-prints-troubleshooting/bed-skew/

Two options seem to be apply some shims to correct the skew, or wait for a possible future firmware enhancement.

 

Posted : 14/05/2020 12:11 pm
awoodbridge
(@awoodbridge)
Active Member
Topic starter answered:
RE: XZ Gantry not square to Y

@steve-e3

1. Yes

2. Parallelogram

3. No

4. The lengths of the sides are correct just shifted.

 

Yes I'm running the latest slicer & firmware, I have recalibrated first layer, and I have proper belt tension.

 

Posted : 19/05/2020 5:41 pm
awoodbridge
(@awoodbridge)
Active Member
Topic starter answered:
RE: XZ Gantry not square to Y

@steve-e3

1. Yes

2. Parallelogram

3. No

4. The lengths of the sides are correct just shifted.

 

Yes I'm running the latest slicer & firmware, I have re calibrated first layer, and I have proper belt tension.

 

Posted : 19/05/2020 5:42 pm
steve
(@steve-13)
Trusted Member
RE: XZ Gantry not square to Y

I would agree with @bobcousins above. If you Google "Bed Skew" there is a video regarding how to build Marlin with bed skew correction, seems like that may be the best solution util if/when Prusa provides a solution. Note that any custom firmware on the Mini requires you to mechanically break a connection and therefore void the warranty.

Posted : 19/05/2020 11:30 pm
3Dprintedgr
(@3dprintedgr)
Estimable Member
RE: XZ Gantry not square to Y

Same problem here. I printed a box and a lid and there was an error in the XY axis. Hopefully this will be corrected with future software updates.

Original Prusa Mini + Smooth PEI
Prusa Slicer 2.6.0

Posted : 03/06/2020 6:22 am
JeffL
(@jeffl)
Eminent Member
RE: XZ Gantry not square to Y

 

My Mini was printing circles as crazy slanted ovals.

I spent a few hours tweaking things... No luck

The solution that worked for me was tighten the crap out of the x-axis belt and boom, perfect circles

Posted : 25/06/2020 12:27 am
Crawlerin
(@crawlerin)
Prominent Member
RE: XZ Gantry not square to Y

MINI's heated bed seems to have those 4 spots which MK2 and 3 use to verify geometry of axes. Maybe in the future, one day, code gets put into firmware and MINI will be able to check at least perpendicularity as part of initial setup?

Posted : 25/06/2020 10:14 am
bobc
 bobc
(@bobc)
Reputable Member
RE: XZ Gantry not square to Y

I noticed the bed has those 4 spots, but the MINDA probe does not have a temp sensor, so it would need a hardware update as well as firmware.

Posted : 25/06/2020 11:39 am
Crawlerin
(@crawlerin)
Prominent Member
RE: XZ Gantry not square to Y

I am under the impression that sensing of those spots is based on changes in electrical induction and not temperature.

Posted : 25/06/2020 4:04 pm
bobc
 bobc
(@bobc)
Reputable Member
RE: XZ Gantry not square to Y

Ah yes, I think you are right. Not sure where I got that idea from!

Good to know it can be done with a firmware update.

Posted : 25/06/2020 4:31 pm
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