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Author Topic: Problem with Z-axis homing to positive infinity at beginning of print :-\  (Read 300 times)

NeoModulus

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I've been having an occasional problem with printing something after killing a previous print in repetier.   

When starting the new print, the bukobot (v2, with Azteeg x3) homes to x0, y0, but when homing to the Z endstop, it hits the Z-endstop switch then retracts in the positive Z direction, upward (like it usually does for a small moment, only this time it goes on for infinity).  The Z-motors continue to move the extruder upward at a slow rate until it crashes into the top of the bukobot, unless it is reset.  Resetting the bukobot, as well as disconnecting/reconnecting via repetier seems to fix the problem.

I just want to get it figured out so it doesn't crash into the top of the bot again if I'm not paying attention. Last time it misaligned itself pretty bad, but fortunately nothing was broken.

Any input is appreciated!

=brando


Rawpork

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Re: Problem with Z-axis homing to positive infinity at beginning of print :-\
« Reply #1 on: December 19, 2013, 08:46:52 AM »
Ive had it happen quite a few times, just hit reset on azteeg, or kill button on the top right corner and it homes head.

Zigor

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Re: Problem with Z-axis homing to positive infinity at beginning of print :-\
« Reply #2 on: December 21, 2013, 01:33:55 AM »
Yeah, happens to me too I just press the reset.

whosawhatsis

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This is a known bug in Marlin that we haven't been able to track down to fix. It only seems to happen when the machine has to move a long way to home Z (I suspect that it is an uncaught counter overflow), so jogging the axis closer to the platform before homing should help.

whosawhatsis

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Finally found the Z home bug. You can get a copy of the firmware with the just the bugfix here: https://github.com/whosawhatsis/Marlin/tree/Bukobot_config

If you're feeling a bit more adventurous, you can instead install this updated branch (shipping on new Bukobots as of the beginning of the new year). This will require a bit of rewiring, but it now includes the bugfix as well as some updated features, and on a Bukobot v2, the motor connectors should now all be facing the same direction (smooth side on top). Note that as part of this update, we have switched to considering "Extruder 1" to be the RIGHT extruder (the one that comes with single-extruder models, and the one that is at the corner of the platform when homed). To use this you'll either have to flip your extruder motor connectors to keep your current extruder order or switch the heater, thermistor and motor wires for the two extruders (recommended). The updated Marlin can be downloaded here: https://github.com/whosawhatsis/Marlin/tree/Bukobot_update

NeoModulus

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Thanks a ton!    I'll be looking into this as soon as i get to a stopping point on my thesis. 
=b

 

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