I have a similar problem as mentioned in an earlier post. The nib the that
sticks up into the bore of my tailstock and keeps the barral from rotating is
all but worn away. Been considering how to tackle a repair. Been thinking of
cutting a notch in the front edge of the tailstock and brazing in a new nib to
fit the groove in the barrel. Any of you ever do this repair? I've always
wondered how the origional was made because the barrel could not be bore with
this nib in place and there is no sign that it is replaceable.

On 12 Dec 2004 14:57:31 GMT, (GMasterman) wrote:

I have a similar problem as mentioned in an earlier post. The nib the that
sticks up into the bore of my tailstock and keeps the barral from rotating is
all but worn away. Been considering how to tackle a repair. Been thinking of
cutting a notch in the front edge of the tailstock and brazing in a new nib to
fit the groove in the barrel. Any of you ever do this repair? I've always
wondered how the origional was made because the barrel could not be bore with
this nib in place and there is no sign that it is replaceable.

If you clean the paint away, you may find that the nib was pressed in
from the outside. An easy repair is to drill a hole in the proper
place, tap for a setscrew (diameter depends on the groove width) and
machine the proper nib on the end of a setscrew, then screw it in with
a bit of loctite to keep it from ever moving. Drill out the original
plug in nib (which I believe is called a "feather" in the old books.

Many machines use this method both on the tailstock and on the
headstock for 5c collet key. This makes it simple to install, and will
allow you to adjust the depth as wear occurs. Hardinge uses this on
their spindle noses as a single example.

Gunner

"To be civilized is to restrain the ability to commit mayhem.
To be incapable of committing mayhem is not the mark of the civilized,
merely the domesticated." - Trefor Thomas

In article , Gunner says...

Many machines use this method both on the tailstock and on the
headstock for 5c collet key. This makes it simple to install, and will
allow you to adjust the depth as wear occurs. Hardinge uses this on
their spindle noses as a single example.

They do this on their *newer* machines. I know for a fact that
they transitioned to the better approach during their manufacture
of the "BB" series lathes. I owned one that had the darn key
pressed in from the outside of the spindle, and the position was
covered over by the front bearing pair!

Of course when I bought the lathe it had the key pretty well
schmooshed over so I had to dismantle the entire spindle, including
*carefully* removing the front bearings, to replace the it.

Then imagine my suprise when I met a local fellow who owned an
nearly identical BB47 machine (seven inch, 4C spindle) which
had the much more modern implementation of an angled drilled
hole, tapped for the setscrew that has the end profiled to
be a collet key once it protrudes into the bore.

The only possible trouble with the setscrew approach to life
in a tailstock is that the casting might not have enough wall
to allow good threads in cast iron. The original poster
will probably find the key was pressed into place.

I *would* have said that red locktite would possibly be
not strong enough. Except for the fact that I've had to
remove setscrews secured with it in the past. The only
way is to heat with a torch...

Jim


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