On Jul 11, 7:52*pm, "Michael Koblic" wrote:
Jim Wilkins wrote:
...The 6" lathe I bought first was a mistake.

Care to expand on that?
Michael Koblic

The 6" Sears / AA lathe's 1/2"-20 spindle isn't stiff enough to turn
steel. When I got it I only intended to make small aluminum and brass
parts for electronics, but then I bought a wood bandsaw that needed a
new lower shaft and discovered that the lathe couldn't handle the job.
If everything went well it cut the steel, however if the bit dug in
from too large a cut, meaning about 0.010" deep, the whole lathe would
twist and I'd have to pound the bent spindle straight again. The fix
is said to be a 3/4" spindle nose like your Taig's. Maybe someday I'll
finish the new spindle I started and bore out the headstock. It isn't
a priority, the small lathe spins faster for polishing but otherwise
doesn't do anything the South Bend can't do better, including make
very small parts.

At MITRE I had a copy of the small Prazi in my lab. Again it was good
enough for electronics or probably small engine models, and stiffer
than the Sears, but someone before me had stripped the plastic feed
gears trying to turn steel on it. It's main fault was the lack of half
nuts, I had to crank the damn feed screw to move the carriage.

Lathes basically make power transmission components. A small one can
do shafts and bushings but not gears and pulleys large enough to
transmit more than muscle power. I think you are beginning to see how
much of a limitation that is.

The jobs that push the capacity of my machines are mostly large wheels
and pulleys, unplanned repairs, and special tools rather than the
small stuff I originally bought them for. The money spent on machinery
has come back as a front end loader and a sawmill nearly for free,
also the abilities repair for $5 instead of replace for $500, to own
things I can't buy and to strengthen the weak failure points of the
current value-engineered commercial products. Often these are plastic
pivots that I replace with stainless steel TIG rod, turned down to fit
and threaded for retaining nuts.

jsw