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Calibration suddenly failing after working for years  

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tom.b11
(@tom-b11)
New Member
Calibration suddenly failing after working for years

Hi, I've had my Mk3 (now Mk3s) for ages and never had an issue with calibrating other than my stupid mistakes (not cleaning nozzle etc).

I have been printing some of the COVID-19 facemasks and noticed a few layer shifts that could prossible cause them to be useless so I decided to run the XYZ calibration again, so ensure that something wasn't skewed. At that point the calibration failed, and its lead me down a rabbit hole, where I have retightened the X axis belt as it was a tiny bit loose, checked all the connections, done a factory reset and even upgraded then downgraded the firmware and I still can't get the XYZ (or just Z on it's own) calibration to work.

It really feels like a firmware issue to me (though obviously thats unlikely cause no-one else seems to have this issue)because it finds the first point fine (and I can see that the PINDA is triggering correctly) but it always fails on the second point.

I had this before when the X-axis wasn't level, but I can't see that's the issue here. The firmware appears to home correctly, then move onto the second point and then rather than winding down the zaxis so the PINDA comes closer to the bed, it moves it up.... and then obviously it doesn't trigger, so it says it failed.

Link to video of cal failure

I have linked a video that hopefully will explain a bit better. The same thing happens on the XYZ calibration when it tries to find the 4 points in the corners. I finds the first one fine, lifts up to travel to the second, then rather than dropping down again, it lifts even further up and fails to trigger....

I really have no idea how to fix this, cause it seems like a firmware issue, but I don't see how it can be? Any suggestions gratefully appreciated.

Posted : 06/04/2020 11:04 am
JoanTabb
(@joantabb)
Moderator
RE: Calibration suddenly failing after working for years

Hi Tom. 

with your printer idle but turned on, and your extruder a little above the heatbed, 

watch the LED on the Pinda, and move a piece of metal close to the end of the Pinda, does the LED Switch on and off? 
now check the LCD Support>Sensors menu, and see if the Pinda reports a changing status for the pinda, when metal comes close, if this works, move the pinda a little to the right and try again, repeat for the full travel of the X axis. 
if the pinda stops reporting changes and remains either on 1 or 0 all of the time, it is likely your pinda wires are fatigued and breaking down. 

In this condition you can get intermittent connections, so the pinda may work close to the left side, but not further to the right. 

this condition can vary with height and horizontal position. 

As a 'get out of jail free' option, you can turn the printer off, disconnect the mains cable, then cut the pinda cable immediately behind the  X axis cable management post (where the flexible part of the wiring starts, and also cut the cable just inside the Einsy box, then strip the cover off both ends, and strip the insulation off the  individual wires. then 'Piece the length out' using flexible wire and insulate the joints with heat shrink tubing and re fasten the  new wire to the wiring loom. 
this should keep you going whilst you wait for spar parts to arrive...   (MAKE SURE that you connect the same colour wires at both ends of the repair, so that the connections go to the same place as normal. 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 06/04/2020 1:53 pm
tom.b11
(@tom-b11)
New Member
Topic starter answered:
RE: Calibration suddenly failing after working for years

@joantabb

Thank you Joan for that great suggestion. You were right! The probe works fine on the left hand side of the bed and appears to work on the right side (i.e. the LED flashes correctly) however looking at the reported status, the value is fixed at 1 when it is on the right hand side of the bed, so there must be a cable disconnect that only appears on the right side.

I will patch this up now as you suggested and give it another go.

Thanks again,

Tom

Posted : 06/04/2020 2:39 pm
lippman.mark
(@lippman-mark)
Eminent Member
RE: Calibration suddenly failing after working for years

I forgot that oiling the bearing bars helped a lot.

Posted : 21/04/2020 10:44 am
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