well, that sucked!
I finished wiring the lathe back up and gave it a bit of a go.
Unbeknownst to me, the potentiometer on the speed control had somehow failed and gone to a dead short.
So when I flicked the power on, the lathe immediately went to full speed and started smoking! The potentiometer was set to "0" speed, so it took me completely off guard when everything went nuts.
Slammed the power off lickity split and there must have been enough power in a capacitor somewhere to engage the dynamic braking.
This caused the chuck to spin on the spindle thread and it threaded itself right off!
Dropped down and whacked the ways (fortunately, on the inside where it doesn't effect anything) and then it literally LAUNCHED itself into the air, directly at my head!
Luckily, even though I'm older and bodily broken, my reflexes are still quick enough that I was able to deke my head sideways as I simultaneously brought my hands up and caught the spinning chuck in mid air!
Was probably 1 sec or less from power on to standing there with the chuck in my hands. It happened that quick, so quick I actually don’t even remember any of the details of what happened. I just recall the broad strokes of the event. I know it happened, I know the chuck came at me and I know I was standing there with a chuck in my hands. The rest was/is pretty blurry…
Well, I needed a change of shorts and a good long sit on the couch with a coffee after that. Not to mention, I had to wait for the stinging in my hand to die down after getting smacked with a lathe chuck doing somewhere around 1500 rpm and hell bent on busting a hole through the opposite wall of the garage.....
Once I was back to a "not shaking" state, I took the speed control apart again. Nothing wrong, no wires chaffed, everything was numbered and connected correctly. But the pot smelled just like burn electronics.
So I pulled it out and took it apart. yep, somehow it had developed a short and killed itself. the control board must have seen that as a full speed command and off it went.
So yeah, the lathe is now laid up until I can get some 5k single turn carbon film 1w potentiometers.
Ugh. One step forward, two steps back....