# Bi-directional Threading - South bend 9A



## martik777 (Oct 18, 2011)

Attempting to minimize the number of steps, I tried threading without the dial, leaving the 1/2 nut engaged. I did a pass toward the chuck, powered off, then powered in reverse to clear the work, set the compound in a few thou and repeated. The threads are slightly off on the reverse cycle which I think is due to 1/2 nut wear, or am I doing something wrong? I have .060 longitudinal play in the carriage with the nut engaged. It threads accurately with the conventional method using the thread dial and working toward the chuck.


----------



## martik777 (Oct 19, 2011)

Geez, it's so obvious now, guess I wasn't thinking, works like a charm. As far as reversing the motor - I have heard others just switch directions on the fly and it reverses in < 1 sec with no ill effects. I usually wait until it stops too. I think I have the original 1/4 HP motor - it weighs a ton!!


----------



## Tony Wells (Oct 19, 2011)

Rick, I have a 3 phase on a mill that does that. Makes for some interesting power tapping in blind holes.


----------



## Tony Wells (Oct 19, 2011)

Rickabilly said:


> Hi tony,
> Are you sure it's three phase?
> 
> It might be _two phase!!_ in the US a two phase motor would probably be labelled "208V",I think, I'm not a US electrician, but I do know a bit about power distribution systems in the rest of the world, and physics be physics wherever we are.
> ...



It's definitely 3 phase. The three phase we use here (wye) has a wild leg, with each leg to neutral measuring 120 , except the wild leg, which when open, can measure over 200 volts. That makes us careful where we connect any control transformers in a machine. Leg to leg, they're all 240. We use a 4 wire system. 3 hots and a neutral, which is earthed.

I'm with you.....theory is great, but sometimes weird stuff happens in the field. I can't vouch for this particular motor, the tag is beat up, because it is located  facing the front, where people with bad aim smack the drawbar and sometimes hit the tag, making it illegible. It might say 208 on it somewhere, but I can't tell it, and the manual doesn't say.


----------

