Spindle speed sensor for a Bridgeport 2J head

Not at all a LinuxCNC question, but does anybody know a good way of mounting a spindle speed sensor to a Bridgeport 2J head? Strictly speaking my machine is a BOSS 5 CNC machine which uses a variant of the 2J head. Any good place to put a gear tooth sensor or something? It would be nice to have a proper encoder, but I'm not sure how.

Thanks

I added a US digital encoder on top where the drawbar usually goes. My mill has a Kwik Switch spindle and does not use the drawbar so it was relatively easy to do. The only problem with that is that when in back gear the ratio is off. I think PIco did a write up on how to add proximity sensors to the back gear as an option.

I originally had an Erickson Quick change spindle, but I had issues with it dropping tools if you got into a chatter situation, basically turning a bad situation into a disaster. I lost confidence in the machine after several of these drops and I changed my machine to a hollow 30 taper spindle with a Maxi Torque-Rite Power Drawbar. So I think I killed the spindle top option, but at least my tools stay in the spindle now

I'll need to search on that back gear option.

Thanks

I found some Pics

The backgear is a messy situation if you end up going in there. It's filled with grease. When I took mine apart, I changed out the bearings which was not necessary but I was already in there so I did it anyway. Then filling it back up with the right amount of grease was a pita as the recommendations I got was for too much. It was running warm and oozing out so I had to scoop some out gain. If you go in there, pay attention to how much grease is in the gearbox and how it displaces when the back gear lever is pulled.

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....