Hi TJB1,
Yes, I´m using the Repetier firmware version 0.91.6. Yesterday I was working to put the bed auto levelling in action, but the z_probe_height was my challenge to understand. I read many posts about, but nothing was clear enough for me. So, I decided to read the Z-probing material from the site of Repetier Host. Suddenly the lights up and all becomes clear to understand. My printer have a fully functional bed auto leveling with Repetier firmware now. So, I made many tests with z_probe_height and could see the results. When my z-probe touches the bed, the z offset is 20.00 mm. The distance between the nozzle and the bed is 0.1 mm adjusted when I put the command G92 X0 Y0 Z0. In reality, when the Z=0 the nozzle is in 0.1 mm of the bed. If I subtract 0.1 from 20.00 mm, the nozzle will be at 0.2 mm from the bed and the Z_Probe_Height will be 19.90 mm. The result at end of bed auto levelling is the nozzle walking above at bed at 0.2 mm.
I edit the Start G-code of the Slicer to automate the beginning of the process . The result is this start G-code;
G28 Z80 ; Home of Z axe at Z_Max
G1 Z75 ; Z axe goes to 75mm and keep away from the Z_Max
G28 X0 Y0 ; Home X and Y axes
G32 S1 ; Bed Auto Levelling
G28 X0 Y0 ; Home X and Y axes
The board of my printer is an Gen7v1.2-BR2b. The secret to bed auto levelling work without crashing the nozzle against the bed is " move the X axe away from the Z_Max endstop and after, type the command G32 S1 ". When the Z-probe touches the 3 times on the bed, the X axis goes up, touches the Z_Max and goes down. A message with the value of the Z height appear. The Bed Auto Levelling is working good now in my 3D printer.