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XYZ Calibration Issue  

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Aaron Coté
(@aaron-cote)
New Member
XYZ Calibration Issue

Hello!

Just finished putting together my MK3 Kit, and everything goes fine during the selftest steps. The issue shows up once the printer tries to do the XYZ calibration, when the first calibration point fails to be located.

My main question is about the extruder position along the X axis during this step. Is the PINDA sensor supposed to pass over the sensor location (dotted circle on the heatbed) or is the extruder nozzle supposed to pass over it? Based on videos I've seen, it appears that my extruder is in the incorrect X location, causing the sensor to not be located.

The PINDA sensor is also flickering rapidly as it goes through this process, rather than turning off when passing near the sensor (which it doesn't really do, since the indicated sensor location is BETWEEN the hotend and the PINDA.

Any help would be greatly appreciated! 🙂

Posted : 01/06/2018 6:00 am
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: XYZ Calibration Issue

Hi Aaron,

the pinda is supposed to pass over the sense circle, ( at the moment it may be sensing the heater tracks and flickering as a result!)

could something be stopping the X or Y carriage moving full distance .

perhaps incorrectly routed wiring, poorly managed zip ties,

maybe something in the wrong place

perhaps a bearing not running freely...

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 : 01/06/2018 10:24 am
Aaron Coté
(@aaron-cote)
New Member
Topic starter answered:
Re: XYZ Calibration Issue

Hmm, the detection of the heating coils makes a lot of sense!

The head will move all the way to the ends of the x axis, so I don't think there's anything in the way. It just moves too far over either when it self homes, or when it starts the xyz cal.

I'll attach a few pics when I get back to it today!

Thanks so far though!

Posted : 01/06/2018 3:14 pm
henry.b2
(@henry-b2)
Active Member
Re: XYZ Calibration Issue

This sounds exactly like the issue I'm having with the MK3 I just finished putting together. I have a call in to Prusa about it and will follow up if they find the solution.

My X axis moves freely back and forth, no binding. Self-test passes the endstop tests, though it does fail on the filament sensor as there is a solder bridge on the chip. I don't know if this matters. Mesh bed leveling and Z calibration work fine so there's no question that the printer can move the X axis well. It finds all 9 points during that test. However it essentially doesn't even try to position the X axis correctly when doing auto-home or when starting the XYZ calibration. If I turn the printer off, manually move the extruder to the center, then turn on and do auto-home it sets the Y and Z axes correctly but leaves the X axis in the center. Same thing when doing XYZ calibration.

Anybody have any ideas on what the problem might be? This behavior I'm seeing is with the latest firmware.

An earlier firmware version (I'm not sure which) got a bit further but would sill use whatever the X location happens to be at power up when seeking the initial points.

Is it possible to hook up to a debugger to see a realtime output of missed steps? that would help in ruling this out of the equation.

Henry

Posted : 12/06/2018 3:43 am
henry.b2
(@henry-b2)
Active Member
Re: XYZ Calibration Issue

BTW - I think the flickering PINDA is due to a change in the newer firmware. I'm not sure which version my board shipped with but it didn't do that. After updating to the latest firmware the behavior changed. The extruder seems to circle the general location of where the test point should be then when the PINDA triggers it starts scrubbing back and forth just at the edge of detection range. I see that the Z steppers are moving the PINDA up and down rapidly during this pass so I guess the new logic is to pass in and out of detection range (hence the flickering).

Henry

Posted : 12/06/2018 3:47 am
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