Sorry for delay getting back…been bit busy catching up with work since my return from hols.
Having had a good play now, and a good few more failed prints, I seem to be finally making some progress…hurray!!
Since I’ve straightened up the Y-axis rails I managed to get the bed just about level anyway, so hard to tell how much the ‘auto-levelling’ is actually helping, but there is a small amount of adjustment in the Z-axis as it prints, and the first layer lines all seem fairly even now.
My prints were failing roughly 70% through the first layer even though it looked pretty flat, and the filament was grinding, but this turned out to be under-extrusion. I’d already calibrated it once since receiving the printer, but having installed various different firmwares something must have changed as it was almost 20% under (18mm under the 100mm extrude) even though it was using my updated figure.
Had a bit of trouble trying to get the first layer to gel together properly, but I think that’s more down to the new Zebra Board being a slightly more textured surface than the glass I was using beforehand. I’m very impressed with it though. PLA grips great without any heating but the board has a small amount of flex so makes removing large parts easy.
Was printing a bracket for my Xbox Kinect which has quite large, flat surfaces and I was getting some horrible wave effects. This turned out to be due to the filament cooling fan (it was coming on at 100% after layer 1), which has now been disabled and won’t be used unless I’m printing small parts.
There are so many variables at play it’s easy to get lost as to what could be affecting what.
Anyway, thanks for your help and persistence! Hopefully this information will be useful to others in future too.