For some reason, the thermistor in Morgan's J-head died last night. The print I set going was completed, and upon startup today I could get no hot-end temperature reading. The thermistor measures open circuit.
Luckily, I had ordered a pack of 10 thermistors for the heated bed, so I replaced the thermistor without much trouble.
At the same time, I also fixed the toolhead square to the Psi arm (it was ever so slightly tilted, the embossed shape that fits into the arm interfered, and I fixed it with the small grinding head on the Dremel). The hollow for the J-head was also cleaned up, and for the first time the hot-end sat square in the toolhead.
I had to re-do the z-axis calibration, as the J-head now sits a few millimeters deeper into the toolhead.
When I was at H4H, Schalk (Heunis) asked whether the slight tilt on the J-head on my printer would make a difference. I answered in the negative, but after thinking about it, I have changed my mind. On a Cartesian printer a slight offset will make no difference, the print would just be offset by that amount, but on a SCARA printer misalignment will show up in lines not being straight (slightly, but the problem will be there). Having a hot-end that is properly aligned (with the centre of the B-arm ends) will make prints better.
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