Spindle speed sensor for a Bridgeport 2J head

Here is the link to the backgear mod from Pico:

pico-systems.com/bridge_spindle.html

I sure like the Pico solution, but it's for a 1J, anyone know if this same trick can be done to a 2J?

Backgear idea is the same.

I wonder if there is enough room in your machine to add the encoder to the splined spindle shaft? That would be ideal as you'll have the actual spindle rpm weather in normal gear or backgear....

I wounder if I could read these supports on the bottom of the Vari-speed belt? Or better press a reluctor wheel (if that's the correct term) on it?

Those spots should be no problem. And since it is steel that your sensor will be reading you won't have to get as close to them with the sensor.

But is twelve pluses per revolution going to suffice? Do you need to know direction as well?