How is babystepping supposed to work with UBL?

I've, after significant effort and many tries, gotten UBL up and running. I'm confused, however, about two things.

First, what am I supposed to put in the start g-code in my slicer? Previously it was G28 and G29, now I'm thinking it should be G28 and ...? G29 T seems like the ideal option, but using that seems to disable UBL (G29 W says it's inactive) and it's clearly not working. G29 A T seems to do what I'd like, but I end up with the print head 0.5+mm over the print bed as it's laying down the skirt. Which leads me to question 2...

How is babystepping supposed to work? If, while the skirt is printing, I enter babystepping mode (click encoder twice), I can bring the head down .5 to .6mm and get actual adhesion. Once the skirt is done, though, the head hops right back up to where it was to begin printing the part.

Clearly, there's something I must be missing...

Well... There are a couple of answers... You have a choice whether UBL is active at reset or power up. I always run my print with UBL automatically enabled. You do that by activating UBL (G29 A) and doing an M500. If you don't like that idea... You can do a G29 D followed by a M500.

For me... With UBL automatically active and alive... My startup gcode is just a G28 with nothing else. If you power up in a disabled state... You want to do a G28 followed by a G29 A.


It sounds like you have your Z_PROBE_OFFSET_FROM EXTRUDER off. You should set this number correctly. And I think you will see the nozzle start at a position that is more reasonable.

If the skirt is printing right... That is no different than what the first layer of the part prints at.... UNLESS you have raft options and such turned on. For that part of what you are seeing, it is very possible you are fighting a slicer problem.

Edited 1 time(s). Last edit at 05/10/2017 12:58AM by Roxy.