Taz Pro needis positive z-offset


Iḿ still having issues with my Taz Pro.

I’ve rebuilt the T0 tool of the dual extruder toolhead because
it turned out that the bearings on the hobb shaft had been destroyed.

now i’m having issues calibrating the printer.

Menu > Autohome
All axes home correctly.

Menu > Advanced settings > Tool offsets > Measure automatically

Then I do
Menu > Autohome
Menu > Advanced settings > Probe Z offset

I place a sheet of 80grams A4 paper on the bed.
T0 crashes into bed, I can see toolhead bending up.

After some adjustment. I get a -0.27mm Z offset.
Anything lower and the paper is stuck to the bed.
-0.27mm is the lowest that I can move the sheet of paper with some friction around,
and I can retract and re-insert the sheet between tool and bed.

Is this correct procedure?
Do I need thicker paper?
Isn’t -0.27mm a very low value if values of -1.10 to -1.25 are quoted ?

How do I create a test print to see is my settings are correct?

When I try to print the vernier on the provided usb stick,
Tool rubs against build surface.

I have to adjust z-offset to positive values?!

What am I doing wrong here??

-0.27mm is higher than typical. I say higher because it is less negative than -1.20 and therefore a higher number that sets the tool head to a higher position.

But I’ve set Z offset on many printers and see numbers all the way from -1.40 to -0.30 or so. It can vary quite a bit.

I would say whatever works is OK even if it is not typical. Just set it higher a few times until you get a good first layer.

Then do a dual extruder print and see that the second extruder matches the amount of squish you see on the filament put down by the first extruder.

Thank you for this explanation.

Well, I was up to 0.65mm on my last attempt. that is +0.65

Also I saw significant height difference between T0 and T1 nozzles.

I think I’ll rebuild the toolhead (I found the required motor alignment tool online)
and see if that brings some improvement.
Then I can retry the vernier print