"Artemia Salina" wrote in message
news
On Fri, 21 Nov 2003 01:33:01 -0600, F. Hayek wrote:
I like the idea of finding something like a South Bend 9" lathe to get
started. And go from there. I'm a Toyota 4x4 enthusiast though, so I
might like to be able to cut some metric threads.
That may be difficult, depending on the particular thread pitch, without
modifying the lathe (i.e. replacing one or two of the gears). The old
South
Bend lathes (and most American made lathes of that vintage) were designed
to work in the inch system, not metric. Some metric threads have inch
equivalents, or are very close, and can be made on old American lathes
unmodified, but not all of the metric threads can be.
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.
The Lindsay publications reprint of the 1934 SB catalog lists this
gear for sale at $30 for a 9" up to $55 for an 18" lathe. At the time, the
basic 9" SB was priced at around $150 -- so the gear's price was fierce even
then.
If you are going to be really heavy into metric, you might consider
a lathe that does both -- it might have to be a new one. As another
alternative, there are always taps and dies -- lot cheaper than a new
lathe.
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