Just got Mach 3 and have been setting it up. On the lathe I got the adjustments to where the spindle rpm seems to be correct with the readout. 
The weird thing is when you turn the spindle off the rpm readout goes back to 60 to 150 never to zero.  Was watching a video and his lathe and mach 3 where doing the same thing as mine  Is this a problem or is there a fix?  Been all over the net but could not find anything.

Thanks Tom

Are you turning it off through M3 or a separate switch?  If the latter, when you turn off M3 doesn't know, you have to click the spindle button on the M3 screen.

I was using a external mechanical switch.  Could set up a solenoid/relay switch and trigger it through Mach 3 and breakout board.  There doesn't seem to be an issue with starting the motor when the screen is already showing a number.  Do you see any potential problems or would you just click off then on , on the spindle screen?

Thanks
Tom

I think it's probably safest to click off then on, but try it and see!

Will do.

Thanks John

Tom