Will this gear box fit my lathe?

nicholasA · Nov 29, 2018

I recently acquired a South Bend 9" lathe (model "907-Y", made in 1937). It does not have a Quick Change Gear Box (QCGB).

A lathe of similar vintage is for sale on Craigslist (it is a model "82-AB", per its tag), and I was wondering how I can tell if its gear box would fit my lathe. It is a 2 hour drive, so not out of the question but a bit far to drive just go take a peak.

Pictures are attached of the two lathes; the one for sale is held together with angle iron.

Thank you,
Nicholas

iwananew10K · Nov 29, 2018

Don't think I would try fitting a gearbox to your existing lathe, not that you couldn't, but be better to just use the new one as is if you buy it.

That angle is only someone's cobbled up countershaft arrangement,and is easily replaced.

be careful or you will end up with a bunch of machines, none of which are ideal for your purpose.

tommy1010 · Nov 29, 2018

It will fit if yours and that one are both wide 9's. The third hole should already be drilled in yours. You will have to use all of the gearing and banjo from the one with the gearbox. You will have to use the lead screw. The apron will have to be changed and your crossfeed screw will have to be swapped. You will get a QCGB with horizontal and crossfeed. Having one for all the parts makes it an easy swap.

nicholasA · Nov 29, 2018

Tommy1010,

Thank you for the reply. I have done some further research, and I understand what you say up to the point of having to switch lead screws. What characteristics would be different between the two lead screws (diameter/left vs right thread/pitch/etc)?

Thank you,
Nicholas

kitno455 · Nov 29, 2018

During the transition from the wide bed 9" to the 10L, the leadscrew moved away from the bed. Your lathe has the later style apron (Series R I guess), which is similar to that of the 10L. The other lathe is the Series O. I think you would find they don't line up.

allan

tommy1010 · Nov 29, 2018

The lead screws are different at the headstock end. See that large area of no thread on yours vs the other. You will have to cut the lead screw tailstock end to fit yours. You may get away with not changing your saddle and crossfeed screw since you already have powered feeds in both directions. Yours is newer and your saddle will not allow you to engage both the horizontal feed with the half nuts engaged. The older one will. There may be a height concern to align the lead screw but I don't think that will be a problem.

kitno455 · Nov 29, 2018

Also, if you are looking to add a gearbox to a lathe, I would add a double tumbler gearbox before a single. It is much easier to make things like metric threads on a double tumbler. Your existing change gears are also compatible with the end gears on a 10L double tumbler, whereas the single tumbler uses finer pitch gears.

allan

johnoder · Nov 30, 2018

Old large Series O with double tumbler fitted

kitno455 said:
Also, if you are looking to add a gearbox to a lathe, I would add a double tumbler gearbox before a single. It is much easier to make things like metric threads on a double tumbler. Your existing change gears are also compatible with the end gears on a 10L double tumbler, whereas the single tumbler uses finer pitch gears.

allan

nicholasA · Nov 30, 2018

Thank you guys for all of your help. I hadn't realized what all was required to add a gear box to my lathe, so I think instead I will just look at buying the simple change gears to use for now. I did also find this video to be helpful.

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