# Back Gears disengage on SB 9



## grnmtfan (Feb 2, 2013)

I'm new to this forum and am looking for some advise/help to keep back gears from disengaging. A little history first... I inherited a 1937 SB 9 model C a few years ago. Mechanically the lathe was in very good shape, it just needed a little TLC. I completely disassembled it, stripped the old paint, repainted it and reassembled it. Everything turned out fine except when I engage the back gears and run in a forward direction they want to pop out. Researching this problem, everyone refers to adjusting the square head set screw on the chuck side of the headstock which puts tension on an internal spring holding the back gears meshed. 

The problem is, my lathe does not have this set screw. On mine the jam nut and slotted set screw on the left side of the headstock where the eccentric handle is located adjusts how tightly the back gears mesh and the only other mechanical tension devise is between the eccentric handle and the left side of the headstock. The handle when pinned to the back gears shaft pushed against a spring which puts pressure on either a ball bearing or bronze slug (I can't remember which it was) which pushes against the back gears shaft bushing to keep it from turning. There is no adjustment to this part other than stretching the spring??

I hope I've explained my problem clearly enough. Any help or suggestions would be greatly appreciated. FYI the back gears worked fine before I cleaned the lathe. 

Richard


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## dwdw47 (Feb 2, 2013)

Hi I have a picture of what I think you want its for a 10" you are being informed about a later style Good luck. I penciled in a couple lines to point out your area.
dwdw47


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## grnmtfan (Feb 2, 2013)

dwdw47

I appreciate the quick reply. The problem is, the adjustment you refer to is the one I'm missing on my lathe. There is no adjustment 'C'. I only have the adjustment on the left back side of the headstock which allows me to adjust how tight the back gears mesh....and the spring and ball arrangement between the back gear engagement handle and the cam on the back gear shaft.


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## pineyfolks (Feb 2, 2013)

Do you have 2 screws one on each end of the back gear shaft from the bottom side? Thats where mine are.


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## grnmtfan (Feb 3, 2013)

pineyfolks

Nothing on the back bottom right (chuck end) of the headstock. I just have the slotted set screw and jam nut on the lower back left side of the back gears. I used "A Guide to Renovating the South Bend Lathe" published by Ilion Industrial Services when I restored the lathe. If you happen to have this publication on page 84, it shows the square head set screw that I am missing. On page 73 is a picture of a 10k (top right picture) of the bushing friction adjustment. Again, this is missing on my model C. Thank you again for your help.
Richard


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## dwdw47 (Feb 3, 2013)

Hi If you took the back-gear handle off and drilled through the spring pocket and tapped the new hole and used a set screw to adjust the spring tension and make a poppet for the drag out of brass or bronze. 
Good luck
Where did you find the "A Guide to Renovating the South Bend Lathe" publication? It would be a nice reference.
dwdw47



grnmtfan said:


> dwdw47
> 
> I appreciate the quick reply. The problem is, the adjustment you refer to is the one I'm missing on my lathe. There is no adjustment 'C'. I only have the adjustment on the left back side of the headstock which allows me to adjust how tight the back gears mesh....and the spring and ball arrangement between the back gear engagement handle and the cam on the back gear shaft.


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## grnmtfan (Feb 3, 2013)

dwdw47

Thanks for the work around. I was thinking of doing something like that but kept hoping I could fix it without having to change the original design. I like your suggestion and think it would probably give me more adjustment than I have now.

The book I mentioned in a previous post can be found on E-Bay. Enter a search of 'rebuild manual for south bend lathe'. It's sold by stevewb and costs $29.95 with free shipping. Well worth the price. He also sells new felts, and oil wicks etc. if you're planning to refurbish your lathe.

Good luck and thanks again for the suggestion.
Richard


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## woodtickgreg (Feb 4, 2013)

grnmtfan said:


> dwdw47
> 
> Thanks for the work around. I was thinking of doing something like that but kept hoping I could fix it without having to change the original design. I like your suggestion and think it would probably give me more adjustment than I have now.
> 
> ...


I used this book and felt kit on my restore, it's a great resource of info and the felt kit was very complete.


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## Hawkeye (Feb 4, 2013)

Not to be too obvious, but is there a threaded hole in that location? If not, it might be possible to drill and tap your own. Part of the process would include drilling a _short_ distance into the bachgear shaft to allow for a ball bearing to drop in under spring power.

If the hole is there, clean it out and add a ball bearing, spring and setscrew.


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## grnmtfan (Feb 5, 2013)

Hawkeye

There is no threaded hole on the chuck side (right) back of the head stock. I was thinking of drilling and threading one in that location but right now I think I will try redesigning the arrangement with the back gears engagement handle on the left end. I'll try and keep everyone posted as to what I end up doing and how it works. Thanks for your suggestion.
Richard


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