Batteries look really good, John. i'd never have thought of making my own ... respect!
Mike, for the X axis I'm not using a scale typically as in John's second photo.? I'm intending to dismantle a caliper, this one ...?
I'm hoping to remount the magnetic tape on the underside of the cross slide and the pcb in/on the saddle.? One of the connections isn't used, but I'm hoping to do a work-around, not exactly to disable the "auto off" function, but to switch it back on via the Arduino before the TouchDRO realises it's lost the BT signal and drops the link.? Although, thinking on my feet here ... it would still be seeing a signal from the Z axis scale ... hmm, needs some consideration, still work in progress!
This is the spec for a Mitutoyo caliper, the one I've bought seems to follow this exactly.
