- Joined
- Jan 10, 2019
- Messages
- 1,042
I bought a Tachulator and needed a way to pick up speed on my PM-935. The Tachulator can also figure out cutter speed in inches per second once you input cutter diameter, which is a perk. There were several promising pick-off points, but all but one would pick up a speed signal that didn't match the spindle. That is, the sensor could be mounted to pick off the pulleys, or the reverse gear, but they'd all give wrong readings. The only place that looked promising was at the top of the spindle, adjacent to the hex end. A wrench (or power drawbar) needs access of course, so it can't crowd that area.
Turning the spindle by hand showed that in addition to the drawbar, an inner race also turns, so that was promising. Better yet, around the outer edge is a large bearing/bushing with two small threaded holes. They're the locking screws for the back gear lever collar. Moving that lever lifts the upper spindle assembly up and down, so whatever goes there has to ride on that to maintain a constant gap.
The pictures show what I came up with. Not shown are the mounting holes, and still to do is mill a slot to run the wires to the rear, and adding a cover for the top, all to keep the wiring and sensor clear of wayward wrenches. Of course, someone's going to say, "why didn't you mount the sensor here instead and save all that bother?"
Turning the spindle by hand showed that in addition to the drawbar, an inner race also turns, so that was promising. Better yet, around the outer edge is a large bearing/bushing with two small threaded holes. They're the locking screws for the back gear lever collar. Moving that lever lifts the upper spindle assembly up and down, so whatever goes there has to ride on that to maintain a constant gap.
The pictures show what I came up with. Not shown are the mounting holes, and still to do is mill a slot to run the wires to the rear, and adding a cover for the top, all to keep the wiring and sensor clear of wayward wrenches. Of course, someone's going to say, "why didn't you mount the sensor here instead and save all that bother?"
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