In article .net, Boris Beizer
says...

South Bend sells/had a conversion gear for the 9" SB and other lathes --
called a "metric transpose gear". It replaces one of the big gears in the
drive train. It is a two part gear with 114 on one wheel and 110 on the
other, giving a 110/114 ratio -- or something like that. Anyhow, you put
this gear in the gear train and voila, the lathe is now metric. Many other
older lathe manufacturers had/have similar change gears. However, be
prepared for sticker shock. Typically, old lathe gears go for about
$1/tooth-- putting this into the $225 + cost category. Even so, the gear is
so rare that that I've heard it go for more than the price of the lathe.

I think the transpose gear was a 127 tooth item. IIRC
Scott Logan sells a pair of gears that gets to within a
few percent of that ideal gear, and he sells them for a
lot less than what the 127 sells for.

I would point out to the original poster that for smaller
threads, one can still use taps and dies.

Jim

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