Thanks Jon. That's a winner of a response. I have no need for another lathe but
I so admire the Sheldon that I do an ebay search on them daily. (Must be nuts!)

Thanks again
Bill

Jon Elson wrote:

Bill wrote:

I am looking at a picture of what appears to be a very nice model
Sheldon lathe:

http://cgi.ebay.com/ws/eBayISAPI.dll...ategory=12 72

The picture makes it appear as if the compound can be positioned
anywhere along the cross slide.

Yup, the Sheldon R-series lathes are quite sophisticated. This is not
a feature exclusinve to the Sheldon, however. The machine in question
is a pre-1968 R-series, with the open QC gearbox and keyed leadscrew.
The post-1968 machines had an 80-speed, closed oil-bath QC box and
a separate carriage feed shaft, so the leadscrew would only be used for
threading. I see the oil pump handle, so this model also has the apron
running in an oil bath. The post-68 machines had multiplate clutches
instead of gears to connect the carriage and crossfeed drives. These
clutches
could be adjusted to deliver just the feed force required, so they would
slip in the case of a crash. This machine looks like it probably has
that, too. Note the screw heads in the middle of the feed advance
handles' shafts. I don't see the auto cutoff that the later machines had,
though. The handles had detents that were connected by linkages inside the
apron, so when the carriage hit the micrometer stop, or the cross slide
brought trip lugs into contact with the cutoff button, the feed handle
dropped out of the detent.

The design of the R-series lathes were the just about the most advanced
available at the time. The headstock is belt driven, and the drive pulley
runs on it's own, coaxial, bearing set, NOT running over the spindle as
so many other machines did. This was to prevent vibration of the
spindle. The reduction gears are on the motor, to keep the gear vibration
out of the spindle. The headstock is lubricated by an ingenious system
that uses the bull gear to throw oil up into a trough hanging below the
top cover of the headstock. Oil holes drip oil to all the places that need
to be lubed. (Funny thing, they specify way oil in the headstock, but
gear oil on the ways!) The late R15 also had a pop-out threading dial,
so that the leadscrew sould not be worn by ANYTHING touching it,
except when threading. You swapped the dial for a blank plug that was
stored
in the side of the apron. I could go on for several thousand more words
describing all the neat engineering features I discovered while overhauling
mine!

In the 9th photo down you can see a
dovetail and what appears to be a gib. Is this actually a gib to
adjust the cross slide or is it a clamp to position the compound along
on top of the cross slide.

What you see there is the clamp that locks the compound swivel base in
position. 2 socket head bolts pull it up to clamp the swivel to the
cross-slide.
The cross slide uses a tapered gib that is positioned by opposing
bolts from the back of the carriage.

I have a 1972 Sheldon R15-6 (15 swing x 42" between centers), D1-6
spindle). It is an incredible machine. Mine had severe bed wear, but I
have fixed up the bed and now am finishing up the crossslide.
I bought it because of the 2.25" spindle through hole, and the high speed
(either 1250 or 2500 RPM depending on whether the dual-speed motor
option is installed). That makes it possible to use it as a completely
general
purpose lathe, many other 15" machines will not do high speed, so you
need a small machine, too. I want to only have one good one.
Note this is a roughly 3500 Lb machine. I cannot lift the tailstock
myself. Even the upper HALF of the tailstock is at the limit of what I
can move without lifting gear! The headstock is the size of a V-8 engine
block!

Jon