Intermittent Auto Bed Leveling Endstop Crashing Issues

I have to babysit the auto bed leveling routine because the endstop will be too low on occasion when the process starts and won't be able to fully extend. I always raise the Z-axis through Pronterface or OctoPrint beforehand, but sometimes the print routine will begin by lowering the Z-axis.

My start g-code for Slic3r is as follows:

Code:

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; 10" i3v 3mm PLA for .40mm Hexagon 8-9-14
G1 Z5 F50 ; lift nozzle
G28; home all axes
G29; level the bed
G1 Z5 F5000; lift nozzle

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I'm running the latest Marlin with Makerfarm-specific and ABL-related settings merged into Configuration.h: https://github.com/csmatt/Marlin/blo...onfiguration.h

Any help would be MUCH appreciated!!

Thanks guys,
Matt

Edit: I also think I have this issue too. I'll try those changes when I get home today. Maybe they're related?

Quote:

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Originally Posted by mattanonymous

I have to babysit the auto bed leveling routine because the endstop will be too low on occasion when the process starts and won't be able to fully extend. I always raise the Z-axis through Pronterface or OctoPrint beforehand, but sometimes the print routine will begin by lowering the Z-axis.

My start g-code for Slic3r is as follows:

Code:

---

; 10" i3v 3mm PLA for .40mm Hexagon 8-9-14
G1 Z5 F50 ; lift nozzle
G28; home all axes
G29; level the bed
G1 Z5 F5000; lift nozzle

---

I'm running the latest Marlin with Makerfarm-specific and ABL-related settings merged into Configuration.h: https://github.com/csmatt/Marlin/blo...onfiguration.h

Any help would be MUCH appreciated!!

Thanks guys,
Matt

Edit: I also think I have this issue too. I'll try those changes when I get home today. Maybe they're related?

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Your #define Z_RAISE_BEFORE_HOMING 4 should exceed your Z offset which you have as 9.7, There is a bug with the current code that will give you an extra 4mm in your offset so your real offset is 5.7 so if you start closer than 1.7 to the bed you will not have enough room to extend the probe. Try setting the RAISE_BEFORE_HOMING to 10 and see if it fixes your problem.

I have also seen the RAISE BEFORE HOME be ignored if I add code to some of the routines, I have not tracked down what causes the move to be ignored yet.

Thanks so much for your reply! I changed the Z_RAISE_BEFORE_HOMING to 10 as you suggested and also added the code suggested in the link to the Y axis moving during Z raise and my problems appear to be resolved!

Quote:

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Originally Posted by mattanonymous

Thanks so much for your reply! I changed the Z_RAISE_BEFORE_HOMING to 10 as you suggested and also added the code suggested in the link to the Y axis moving during Z raise and my problems appear to be resolved!

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Glad it works for you. These types of problems can be a pain to track down. If you added the fix for the Y moving your Z offset might not be 9.7 anymore. If your nozzle is too high to print, check the offset again. The code change will remove the 4mm error so -5.7mm would be the offset I expect for you. It fixes both the Y Moving and the incorrect height after G28. If you always do a G28 then G29 you would not see the problem. I do a G28 only a lot of times, I use the G29 more to measure the bed than to correct it.

I tried using values other than 10 for Z_RAISE_BEFORE_HOMING and got crashes. I'm gonna stick with both changes. Thanks again for your help!