Rostock max Z problems

[grayd]

Hello all. During calibration of the hot end I had to upload the new hot end cycle settings to the firmware on the Rambo card. After doing this, my Z location became invalid. After moving the hot end (via manual entry of Gcode in the Repetier Software) down to double check the deck calibration I discovered the Z zero was below the heated bed (in fact, the nozzle crashed into the deck). After testing I found that moving the hot end down 10mm actually moved it 20 mm. I then found a reference on the forum here to 8 bit vs 16 bit rambo boards where the hot end would only go down half way. My problem was the opposite of this, so I halved the step value from 106.66 to 53.33. This gets me close, but now my hot end z value shows zero in the repetier sofware when its still 30 mm above the heated bed (and build plate). Running the hot end up to the limit switches and running it back down to zero accomplishes the same thing, a 30mm gap, and I can't manually jog it down past this point. How can I reset the Z value so the hot end nozzle goes back to true zero (where paper drags under the nozzle when the Z value is zero)? Any help appreciated.

[Polygonhell]

Hello all. During calibration of the hot end I had to upload the new hot end cycle settings to the firmware on the Rambo card. After doing this, my Z location became invalid. After moving the hot end (via manual entry of Gcode in the Repetier Software) down to double check the deck calibration I discovered the Z zero was below the heated bed (in fact, the nozzle crashed into the deck). After testing I found that moving the hot end down 10mm actually moved it 20 mm. I then found a reference on the forum here to 8 bit vs 16 bit rambo boards where the hot end would only go down half way. My problem was the opposite of this, so I halved the step value from 106.66 to 53.33. This gets me close, but now my hot end z value shows zero in the repetier sofware when its still 30 mm above the heated bed (and build plate). Running the hot end up to the limit switches and running it back down to zero accomplishes the same thing, a 30mm gap, and I can't manually jog it down past this point. How can I reset the Z value so the hot end nozzle goes back to true zero (where paper drags under the nozzle when the Z value is zero)? Any help appreciated.

Firstly, the microstep change you mades was the right thing to do.
The host software will not let you jog down lower than what it thinks is 0, so first you have to set the ZOffset large enough to be able to reach the bed, If you're currently stopping 30mm above it increase the value in the Firmware by say 40 that will put 0 below the bed, but you can then jog down until the head just touches the table and use M114 to get the current Z coordinate subtract that from the ZOffset, and after uploading when you home Z= 0 should be on the table.
What the ZOffset is called in the firmware depends on which firmware you are using.
The manual covers this in some detail for Marlin.

[noddynomolos]

Well that is always fun! I too crashed my extruder head unto the table.. Sure woke me up
Can't seem to locate the ZOffset in 'Marlin for Rostock Max'.
Like you 'GrayD, I measured the jog values and found them to be 20mm as well. As yet I have not adjusted the step values.
I did, however jog down and did a M114 and got X:0.00Y:0.00Z:167.50E:0.00 Count X:399.86 Y399.86 Z399.86
Any suggestions on how to proceed would be appreciated... Please keep it simple as I am a human mechanic and this is a 'brave new world' for me
Yours,
Don S.