Z Cal Help

Hi
Can someone explain to me why the Z height cal appears to be lost after i do a bed compensation run ( G32 command )

I am trying to print the first axis test print and as it is a large print thought i better calibrate the bed level. I successfully set the IR probe level with G31 Zx.x Pxxx and Z height with G92 Z0.
After homing Z the Z height is perfect and also after a power cycle it retains the correct Z height. HOWEVER after i perform a G32 bed level compensation the Z then homes to a point a few mm above the bed and prints at this height. ( Or should i say tries to print at this height )

i know i could do a manual compensation and create a set bed.g file and run that but i liked the idea of the machine using the iR probe and calibrating itself whenever i feel the bed may have moved.

( I have on order one of the ALU bed upgrades so probably may be a moot point when it arrives )

Thanks
Dean

I know the software compensation sounds neat and I was in that camp when I first fired it up. How clever I thought that the software can level the bed by adjusting the Z as it moves around. This applies to either manually doing a setbed series of measurements or the automated method.

However, for me manual levelling and no compensation, was the way to go, and once I'd made the switch the benefits became obvious to me. The only z motion is between layers, so no continuous motion of the lead screw which potential causes wear problems, plus I find it much quicker to get into printing after turning on. Stability of the bed is key to this as well and there is much activity on mods to improve that.

Hi Dean, you need to edit your homez.g and homeall.g files so that the Z homing point is at the same place as your first bed calibration point - and of course all the bed calibration point must place the sensor head over the centre of the white tape. The default Z homing point in your homez.g file is probably placing the head off the centre of the white tape, where the Z probe reading is a little different.

Edited 1 time(s). Last edit at 03/12/2014 01:30PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].