Help with southbend 9 model B

wce4 · Aug 9, 2024

Looking for some advise/help to keep back gear from disengaging.
When I run the lathe with the back gears engage and take a cut the back gear in mid cut disengages. This just started happening today. I have a second southbend 9 a to compare with but everything seams to be the same. (As my late father-in-law would say same- same) Is there some kind of adjustment for this ? Any help or suggestions would be greatly appreciated.

krypto · Aug 10, 2024

First, are you sure the cone pulley is lubed? Does it turn easily? With my lathe, in the cold winter sometimes the lever will want to move until the cone pulley loosens-up a bit. I would usually hold the lever when turning on the lathe and then it would be fine when running.

On my lathe, there is a tension adjustment for the back gear lever below the back gear shaft on the right side behind the chuck. Some models/years are different.

HMEL · Aug 10, 2024

wce4 said:
Looking for some advise/help to keep back gear from disengaging.
When I run the lathe with the back gears engage and take a cut the back gear in mid cut disengages. This just started happening today. I have a second southbend 9 a to compare with but everything seams to be the same. (As my late father-in-law would say same- same) Is there some kind of adjustment for this ? Any help or suggestions would be greatly appreciated.

adjusting back gears from south bend manual for 9, 10k, 10 and 141/2 only
1. Engage back gears using eccentric shaft lever and allow mating gears to bottom. Then back off back gears until you feel a slight rock between mating gears and tighten screw set screw( on housing by handle) Tighten screw on the other sides so tension on eccentric bushing is enough to hold the gears in on a heavy cut but not so tight that the eccentric shaft lever is hard to operate. Make final adjustments by allowing lathe to run for a few minutes. If there is an abnormal amount of noise such that as a gear rattling noise the gear clearance is to great, adjust b slightly unscrewing set screw on the handle side. If it seems to be a howling noise the gear clearance is to insufficient. Adjust by screwing in the set screw near the handle. When proper clearance is obtained, lock the set screw with the nut.

Note this is what I cal a hunt a peck operation. The design works on an eccentric shaft which rolls the gears into and out of position. Simple but effective. There are two set screws one does the adjustment and the other sets the resistance to the movement of the shaft once in position. Based on your complaint you may get away with adjusting the screw on the end without the handle ( the one for handle resistance)
Good Luck

wce4 · Aug 10, 2024

krypto said:
First, are you sure the cone pulley is lubed? Does it turn easily? With my lathe, in the cold winter sometimes the lever will want to move until the cone pulley loosens-up a bit. I would usually hold the lever when turning on the lathe and then it would be fine when running.

On my lathe, there is a tension adjustment for the back gear lever below the back gear shaft on the right side behind the chuck. Some models/years are different.

Thanks for the for the suggestion Krypto, I check the cone pulley it is lubed and it turns freely
with the belt disengaged. The lathe runs ok in back gear when there is no load, but when taking a 10 thou or more cut that is when the back gear disengages.

wce4 · Aug 10, 2024

HMEL said:
adjusting back gears from south bend manual for 9, 10k, 10 and 141/2 only
1. Engage back gears using eccentric shaft lever and allow mating gears to bottom. Then back off back gears until you feel a slight rock between mating gears and tighten screw set screw( on housing by handle) Tighten screw on the other sides so tension on eccentric bushing is enough to hold the gears in on a heavy cut but not so tight that the eccentric shaft lever is hard to operate. Make final adjustments by allowing lathe to run for a few minutes. If there is an abnormal amount of noise such that as a gear rattling noise the gear clearance is to great, adjust b slightly unscrewing set screw on the handle side. If it seems to be a howling noise the gear clearance is to insufficient. Adjust by screwing in the set screw near the handle. When proper clearance is obtained, lock the set screw with the nut.

Note this is what I cal a hunt a peck operation. The design works on an eccentric shaft which rolls the gears into and out of position. Simple but effective. There are two set screws one does the adjustment and the other sets the resistance to the movement of the shaft once in position. Based on your complaint you may get away with adjusting the screw on the end without the handle ( the one for handle resistance)
Good Luck

HMEL Thank you for the information much appreciated, I will give it a go tomorrow. I hope not to make things any worse then it is. This should be interesting. Thanks again.