Issue : All carriages raise without stopping when linear move to some XY points

Having issues with bed leveling (I think) and need advice.

I have a Folgertech Kossel printer with a Ramps 1.4 board.

I have been using the printer for the last year and a half without much issue. I upgraded the firmware to Marlin 1.1.8 to try out the improvements on the bed leveling. When the printer goes to some points it will move to that point and then all three carriages will raise up simultaneously and I have to kill the printer. If I don't the carriages just drive themselves into the endstops over and over. When I turn off the bed leveling with "M420 S0" I can move to the same points without issue. This makes me believe it has something to do with how the bed leveling mesh affects linear motion.

The position where the printer carriages all raise can have any Z value. The error occurs only in the X+, Y+ quadrant and X+, Y- quadrant and only outside of 60mm from the center of the bed (print bed is reachable in a 90mm radius). When I look at the bed leveling mesh below there seems to be a correlation with the problem areas and negative numbers in the mesh.

Here is the outputs from "G29 T"
Bed Topography Report:
(0,6) (6,6)
(-60,60) (60,60)
. . 1.620 1.060 0.595 . .

1.870 1.451 1.087 0.853 0.449 0.088 -0.509

1.292 1.092 0.875 0.623 0.338 0.017 -0.333

1.050 0.836 0.648 [ 0.405] 0.198 -0.039 -0.282

0.665 0.688 0.501 0.310 0.114 0.000 -0.185

0.483 0.354 0.310 0.175 0.060 -0.083 -0.232

0.344 0.211 0.196 0.072 -0.033 -0.122 -0.193
(-60,-60) (60,-60)
(0,0) (6,0)

Other than just trying one of the other bed leveling methods I'm not really sure where to go from here. I want to get the auto bed leveling to work. Anyone have any suggestions or insight on this issue?

It seems, your height variations are way too much. Try to level the bed and equalize the endstop trigger height manually and autolevel from there.
I hope it's not the z-probe itself causing such height errors?

Thanks. That's as good of a place to start as any. I'll post again after.

I did remake the hot bed assembly as I found the spacers that the hotbed mounted to were not all the same thickness. After putting it all back together I did a couple G33 commands and a G29 to do the UBL leveling and all seems to be more level now. Below are the current bed numbers.

SENDING:G29 T
Bed Topography Report:
(0,6) (6,6)
(-60,60) (60,60)
. . 0.534 0.419 0.186 . .

0.677 0.242 0.300 0.090 0.064 0.015 -0.169

0.247 0.058 0.123 0.073 0.038 -0.002 -0.197

0.048 -0.039 -0.015 [ 0.061] 0.000 -0.123 -0.187

-0.014 -0.064 -0.073 0.000 -0.075 -0.060 -0.060

0.013 -0.051 -0.048 -0.050 -0.059 -0.048 -0.039

0.059 0.032 -0.002 -0.023 -0.026 -0.052 -0.012
(-60,-60) (60,-60)
(0,0) (6,0)

With bed leveling on I still have the issue where when I move to some points all three carriages continue upwards to max end stops and never stop...with bed leveling off, the issue goes away.

Edited 1 time(s). Last edit at 06/15/2018 12:12AM by boxybb.