Jim Wilson
Aluminum
- Joined
- Mar 25, 2007
- Location
- Tucson, AZ, USA
I'm being punished for bringing my lathe back to life. Three of four bugaboos resolved; but now a new one rears its ugly head. I guess all progress has a price. In case you haven't been following this saga, the machine is a 1993 Hardinge Conquest T51. It's had a hard life, but we can rebuild it.
The new problem is: it will no longer zero-return in X. This just started about an hour ago. Specifically, when you get to the step where you "hold down -X until the cross-slide stops on its own," it never stops. It keeps going all the way down until it hits the -X overtravel limit. This happens even if it starts way, way up high (like up to about 0.010" below the +X overtravel) and of course, despite getting a good solid 2.5" of -Z travel before starting X.
Here's my first question. It's supposed to stop when the turret reference point reaches 2.5" diameter, right? How exactly does the machine know it has reached that point? From the zero-return limit switch? That would be switch 7ALS. On the electrical schematic, that switch is labeled X AXIS DECEL, but the maintenance manual calls it the zero-return limit switch.
Anyway, the signal from that switch arrives at 13TB-10 (bit B0). As the -X movement proceeds, I can watch 13TB B0 wink out and then come back on as the dog passes the switch. So the switch is working fine. Does that mean there some other event that stops the -X travel at 2.5"?
The new problem is: it will no longer zero-return in X. This just started about an hour ago. Specifically, when you get to the step where you "hold down -X until the cross-slide stops on its own," it never stops. It keeps going all the way down until it hits the -X overtravel limit. This happens even if it starts way, way up high (like up to about 0.010" below the +X overtravel) and of course, despite getting a good solid 2.5" of -Z travel before starting X.
Here's my first question. It's supposed to stop when the turret reference point reaches 2.5" diameter, right? How exactly does the machine know it has reached that point? From the zero-return limit switch? That would be switch 7ALS. On the electrical schematic, that switch is labeled X AXIS DECEL, but the maintenance manual calls it the zero-return limit switch.
Anyway, the signal from that switch arrives at 13TB-10 (bit B0). As the -X movement proceeds, I can watch 13TB B0 wink out and then come back on as the dog passes the switch. So the switch is working fine. Does that mean there some other event that stops the -X travel at 2.5"?