Need to have z offset set to 0.25mm before printing

vistalert

Thanks to the patience and guidance of all here I've been able to get my printer finally assembled, and run off my first prints. I find that I have to set the Z Offset to 0.25mm then I get a good bottom layer adhering to my PEI surface.

So, when I home Z, would I just use:

G91
G1 H2 Z0.25
G92 Z0
G90

...or is there a magic setting somewhere that can be "set and forget", which I've missed?

Also, after my print completes, I run my bed park script (drops the bed to maximum extent. I want to include commands in this that turn off the hotend and bed. At the moment I only found out how to just set the temps to zero. But they remain in "active" state, with temp set at zero. How do I set them so they go inactive, and temps at 0?

Thanks
Chris

fcwilt

Hi,

As to your Z position issue normally Z=0 is where the nozzle is just touching the bed, when bed and hotend are at working temps.

Are you saying that is not true for your machine?

As to saving the current values that you appear to need the correct place is in homez.g - just as you are doing.

To turn off both bed and hotend I have been using this:

G10 P0 S-999 R-999	; turn extruder heater off (also sets temps to zero)
T-1          		; deselect all tools

M140 S0             ; set bed heater active temp to 0
M140 S-999          ; turn bed heater off

Frederick

vistalert

@fcwilt thanks for the quick reply.

At z=1.3 I can just get a 1mm feeler gauge between bed/nozzle. The feeler gauge is just brushing the nozzle.

My BLtouch probe Zoffset is out by 0.2 hey?

; Current setting form config.g for Z probe offset
G31 P500 X-26 Y-5 Z2.255

This Z offset was set by doing the paper grab and G30 S-1 to get probe offset, avering three reading.

Is this what I need to tweak?

Veti

@vistalert

the manual measuring is just to get you close, then fine tune with babystepping until you get a good first layer and adjust the offset by the babystepping amount.

vistalert

@Veti - awesome. Should I subtract 0.2mm from the Z Offset in config.g?

Veti

subtracting from the offset puts the nozzle further away
adding puts the nozzle closer
(hope i got that right, one of the things i always get confused by)

vistalert

@Veti haha yep that's why I asked you coz I'm confused too. I can try it out. Will let you know.

vistalert

Thanks every one - dropping the Zoffset slightly, in config.g has brought the nozzle spot on to 1mm from the bed with Z=1.