First post out of what I assume will be many. Hope you guys can help me out. I can't seem to figure out auto-bed leveling on my machine/firmware. I guess I don't understand the relationship between Z probe settings and Auto-Bed settings. First my info
RepRap Guru Prusa I3 Acrylic
Marlin Firmware
Repetier Host- Slic3r built in for slicing.

The firmware that came with the machine was marlin pre-bed leveling. Desiring bed leveling I downloaded the most recent marlin, and ported over all the relevant config.h settings from the version supplied to me. It works fine, prints fine etc. I'm using a z prove mounted on an servo setup, and I have that functioning perfectly. I set my offsets perfectly. When I home all using the probe then move the Z down to 0 manually in repetier host I get just the right friction on a piece of paper (at x/y middle). My problem is I don't understand the interplay between autobed leveling and my Z probe levels. I'm currently editing my G code to home all (safe homing enabled) with g28, then run auto bed with g29, then print. The Z is set perfectly after g28, but after the autobed g29 it is set too low, jamming the extruder. Does the g29 command disregard the results of the g28 operation? Do I need to set an additional offset somewhere to get my g29 height set as well as my g28 height? I don't get it. The bed leveling function probes four locations, then extrapolates the supposed plane of the bed,you would think lowering to 0 at any given x/y would bring you to the perfect height. I know its working because although it sets Z too low, I can watch the Z motors spin as it moves across the first layer. Obviously the auto bed level isn't truly integrated deeply with the system I'm using, because theoretically moving around X and Y manually should change the displayed Z height (as far as that number is representing the distance to the bed) but it doesn't.

TLDR; After G28 lowering Z to 0 gives me perfect clearance, after G29 its too low, what gives?


Thanks!