Which bit?!! (there's nothing confirmed about the driver board - just an inkling only that it might be the problem ....it's certainly caused me no end of problems & googling reveals that A3977s should never be socketed blah blah). The significant part for me was that one remaining A3977 on my board is still fully working & therefoe allows microstepping, so yesterday I dropped that particular chip into my stepper board's Z axis position ....my probed errors became less (about 0.1mm vs 0.350mm over the same 10mm Y0->Y10 probing run ...now if it was mechanical or bed levelling, I reckon the error would be the same no matter what the resolution of the steppers.
I wasn't keeping this a secret - my 'post 11' on this thread yesterday alluded to this!
the thing is I'm likely to be coughing up for a better machine (which will come with very good stepper drivers), so just need to limp on investigating as best I can ...probably until the chap I'm buying off has more machines in stock (22nd feb)
oh...btw - All your jokes are falling ahem 'flat' :heehee: