Multi-purpose lathe spindle mount

thingiverse

When the motor died on my 12" x 37" gap bed metal lathe I took the opportunity to make a few planned upgrades including converting the lathe to a variable frequency drive and 3 phase motor. Of course that meant that I would need to either manually calculate speeds using the motor frequency and selected gearing or I'd need to install a tachometer. I went with a tachometer so in future I can also have an Arduino calculate the workpiece surface feet per minute and the lathe feed rates. The tachometer display and speed control potentiometer are housed in a control box on the head stock. See link for those components https://www.thingiverse.com/thing:5178575 A tachometer requires mounting a magnet on the spindle and designing a bracket for a hall effect sensor. The best place for the bracket and sensor where it wont interfere with things on my lathe is on the outboard end of the spindle. This also happens to be where I wanted to install an indexing system. This meant designing a multi-purpose mounting hub that could be used to mount various types of discs such as a balanced magnet disc, slotted optical sensor discs or various indexing plates. A corresponding bracket is used to mount either a 12 mm diameter hall effect sensor or a 1/2" threaded indexing pin. I've elected to go with a retractable spring plunger part number 8507A12 from McMaster Carr. The tachometer is mounted on the lathe headstock in a detachable control box along with a 10K potentiometer to control the speed via the VFD. Ultimately this box will have an arduino, and LCD keypad shield and the potentiometer. I only need to modify the control box with a new front panel once I am ready to swap out the original tachometer. NOTE: If your spindle is a little under size or the outer disc is slightly over 75mm try using the ALT BLOC Taper as it has a slightly smaller bore.