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tirendel
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MK2 MMU failing calibration at the start of any print.

Mar 22, 2018 8:58 pm

Hi Folks,

I have a Mk2 MMU which runs the stand-alone 9-point calibration correctly every time but fails it at the beginning of each print. I've tried using the models that came on the SD card but it fails with these too.

At the start of each print the printer does the first 3 points of calibration just fine but on the 4th it will jam the hot end into the bed several millimeters. Again this does not happen when I do the Z calibration (or the ZYX calibration for that matter) from the Calibration menu on the screen.

Any help would be appreciated as the printer is unusable at the moment.

ADVthanksANCE.

neil.w
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Re: MK2 MMU failing calibration at the start of any print.

Mar 31, 2018 1:29 am

I would suggest lowering your P.I.N.D.A. probe slightly, by 0.5-1.0mm. You may also need to rerun a Z calibration but this should fix your issue.

roger.c
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Re: MK2 MMU failing calibration at the start of any print.

Apr 03, 2018 4:20 am

Are you using previously sliced g-code or are you re-slicing for MMU? I also have the problem with the G-code parts provided in the package, I have success when I re-slice the Prusa parts again for MMU.

lionel.p
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Re: MK2 MMU failing calibration at the start of any print.

Apr 03, 2018 8:35 am

I had random issues with the 4th calibration point as well and actually damaged my PEI sheet. The problem was due to zip ties near the spiral wrap ( https://d17kynu4zpq5hy.cloudfront.net/i ... Jo2i.large) that were actually "slightly" messing with the x-endstop on some occasion. One time it was enough to crash the hot hotend on this particular 4th point and melt the PEI sheet (I will replace this one later as it is now an issue when I need to redo a full calibration). Moving the zipties/wrap eliminated the problem since then.

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tirendel
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Re: MK2 MMU failing calibration at the start of any print.

Apr 05, 2018 8:49 pm

roger.c wrote:
Apr 03, 2018 4:20 am
Are you using previously sliced g-code or are you re-slicing for MMU? I also have the problem with the G-code parts provided in the package, I have success when I re-slice the Prusa parts again for MMU.

I've used both and many different files. Ones that came with the printer, ones sliced using Slic3r PE and ones using Simply3D. They all fail at the 4th Calibration point. But again it runs properly when I do "Settings -> Calibration -> Calibrate Z".

The interesting thing is that it has worked in the past but then I didn't use the printer for about 2 months and then this started happening.

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tirendel
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Re: MK2 MMU failing calibration at the start of any print.

Apr 05, 2018 8:51 pm

lionel.p wrote:
Apr 03, 2018 8:35 am
I had random issues with the 4th calibration point as well and actually damaged my PEI sheet. The problem was due to zip ties near the spiral wrap ( https://d17kynu4zpq5hy.cloudfront.net/i ... Jo2i.large) that were actually "slightly" messing with the x-endstop on some occasion. One time it was enough to crash the hot hotend on this particular 4th point and melt the PEI sheet (I will replace this one later as it is now an issue when I need to redo a full calibration). Moving the zipties/wrap eliminated the problem since then.

I will definitely check the zip ties at that point. Thanks for the insight.

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tirendel
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Re: MK2 MMU failing calibration at the start of any print.

Apr 05, 2018 8:56 pm

neil.w wrote:
Mar 31, 2018 1:29 am
I would suggest lowering your P.I.N.D.A. probe slightly, by 0.5-1.0mm. You may also need to rerun a Z calibration but this should fix your issue.

Thanks Neil, I hadn't considered this. I can certainly try it.

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