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WTB: South Bend 11" quick-change drive gear / banjo gear

Koreth

Plastic
Joined
Mar 13, 2022
Location
Colorado
My hackerspace's 11" South Bend lathe has taken damage to the gearing that transmits force from the spindle to quick-change gearbox. Specifically, the large 64-tooth gear which meshes with the feed-reverse lever and the sliding gear on the banjo, has had 4 teeth snapped off. I've attached marked-up diagrams from the 1935 parts catalog.[1] I have also seen this gear called the "banjo gear". This gear is marked "652" on the diagram, and has "11-652" cast into its side. I count 64 teeth, measure 4.127" overall diameter for a diametral pitch of 16, and the gear has a face width of 5/8". I have not yet measured the bore, as I have not yet disassembled the banjo, but suspect it it to be about 3/4", based on measurements of the sliding gear shaft.

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I wrote Ted Pflugner at his email address of [email protected], listed in the stickied post, South Bend Links: Sources for Info, Parts, and Supplies. He did not have this gear in stock. I have also had no luck searching eBay.

Does anyone perchance have this gear, or a compatible gear? Might anyone be able to recommend someone who might have it or a compatible gear in stock?

1. http://vintagemachinery.org/pubs/1617/3754.pdf
 
I got the banjo apart and got a chance to inspect things closer. Once I got the primary gear ans spur off, I noticed something odd:
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There appears to be some kind of pin or insert where the primary spur and primary gear press together. It looks like it was ground or maybe turned flush, so I didn't notice it at first. However, once I got the primary gear and spur pressed apart, it was more clear. There is some kind of pin acting as a sort of key and there's a corresponding slot on the pinion.

I am not sure if this is someones repair to stop slippage, or a bodge done at the factory to salvage what might have been thrown away for an insufficient interference fit. But I don't see any reference to such a pin in any of the drawings or pictures of the part in the 1930, 1934, or 1934 parts catalogs for the "O" series on Steve Wells' website. And it does not look well-centered either; most of the pin is in the primary gear, instead of being equally spaced between the pinion and gear. If this were intentional from the factory, in addition to seeing it mentioned in the parts lists and drawings, I'd expect it to be square and better centered. Rather, it looks like someone put the pressed-together pinion and gear up on a drill press, drilled a hole, then drove a pin into place, and then ground or turned off the excess.
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Has anyone else had the gear train between the headstock and quick-change gearbox apart? Is this pin normal? Or do I have someone's makeshift repair on my hands?

I mainly want to know so I know whether or not to include it in any drawings or specifications in ordering a replacement gear. I'm thinking that if this is someone's makeshift repair, than I can ignore it in any spec I submit to a gear cutter, and instead make sure to specify the tightness of the interference fit correctly.
 
My hackerspace's 11" South Bend lathe has taken damage to the gearing that transmits force from the spindle to quick-change gearbox. Specifically, the large 64-tooth gear which meshes with the feed-reverse lever and the sliding gear on the banjo, has had 4 teeth snapped off. I've attached marked-up diagrams from the 1935 parts catalog.[1] I have also seen this gear called the "banjo gear". This gear is marked "652" on the diagram, and has "11-652" cast into its side. I count 64 teeth, measure 4.127" overall diameter for a diametral pitch of 16, and the gear has a face width of 5/8". I have not yet measured the bore, as I have not yet disassembled the banjo, but suspect it it to be about 3/4", based on measurements of the sliding gear shaft.

View attachment 429301View attachment 429302

I wrote Ted Pflugner at his email address of [email protected], listed in the stickied post, South Bend Links: Sources for Info, Parts, and Supplies. He did not have this gear in stock. I have also had no luck searching eBay.

Does anyone perchance have this gear, or a compatible gear? Might anyone be able to recommend someone who might have it or a compatible gear in stock?

1. http://vintagemachinery.org/pubs/1617/3754.pdf
I also had an issue with my back gear on my SB11. I ended up making new teeth and cutting a dovetail joint,then pressing them into place. Did 3 teeth on one gear and one tooth on ther smaller back gear. Worked out well. Just need to have a mill Attachment and modify or make a cutter for the dovetail joint. If you are interested I can send pictures and information on the process. Everything was completed on a lathe since I don't own a milling machine.
 
I also had an issue with my back gear on my SB11. I ended up making new teeth and cutting a dovetail joint,then pressing them into place. Did 3 teeth on one gear and one tooth on ther smaller back gear. Worked out well. Just need to have a mill Attachment and modify or make a cutter for the dovetail joint. If you are interested I can send pictures and information on the process. Everything was completed on a lathe since I don't own a milling machine.
I think I have found a shop I can cut a new gear for me, but I am curious of your method as well. Please post pictures and a description of the process?
 








 
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