On 8 Dec 2005 05:33:04 -0800, jim rozen
wrote:

In article , Ned Simmons
says...

Gunner will no doubt correct me if I'm wrong, but my understanding
(based on his overhaul instructions) is that the outer races
are separated only by the headstock casting. These machines do not
have a 'cartridge' per se. The rear bearing comes out the back,
the front one comes out the front.

Yeah, I just looked in the HLVH manual. I don't know how I
got it in my head that it's a cartridge spindle, unless on
account of a Rathbone chucker I once had which was a
functional copy of an HC. The Rathbone did have a
cartridge. A functional copy in that all the HC tooling and
attachments fit - it was constructed more like the Monarch
chucker with round ways.

But there is a separate spacer that appears to be pinned in
the headstock casting that separates the bearings' outer
races.

Interesting, I've never seen an exploded diagram for one
of those, nor have I had one that far apart. A steel cylinder
pinned into the casting would indeed eliminate the thermal
expansion issue to a large degree, and likewise put all the
"sin" in getting the OD race separation away from the rough
headstock casting, into something that could be more tightly
controlled during manufacture. All things that hardinge could
be expected to figure out, and implement.

There is indeed a cylinder inside the head, but its a hard pressfit
into the headstock casting and pinned via a steel taper pin from top
dead center of the headstock. I actually broke one free from a
headstock that had a heavily rusted in bearing. Using my 20lb bearing
knocker with a 10lb sledge sorta got it moveing...G

But IRRC..the cylinder doesnt contact the outer race. Ive still to do
that DV-59 yet...Ive had pnuemonia ..sigh and Ill check carefuly when
I yank the spindle.

Gunner


My real concern is that for the rear radial bearing to float, it must
have some non-zero clearance in the headstock bore. Even if small it
is present and will serve to reduce the rigidity of the *rear* of the
spindle. The BB headstock machine I overhauled had the rear bearing
fitted snugly but I was able to extract it without resorting to heroic
measures.

I don't disagree, but think the bearing's radial looseness
is a more likely culprit. Barden recommends a transition
fit, around .0002 either side of line to line, for the
housing in this situation. I'd describe the housing fit on
the 3rd bearing in the few spindles I've had apart as a
wringing fit - tighter than a slip fit, but moves with firm
hand pressure.

Yep, that's just about what I felt when I removed the spindle
from that BB headstock lathe.

In either case, movement due to radial
clearance in the bearing itself or radial movement of the
bearing in the bore, you'd expect to see a knee in a force
vs. deflection curve. I mentioned in an earlier post in
this thread that I was able to see the effect of the radial
bearing in a BP spindle by measuring the difference in
deflection at the nose with the top radial bearing both
removed and installed, but I don't recall checking for a
change in stiffness as the top bearing loads up. So I just
did a quick test with a spring scale and indicator on the
BP.

I mounted a 50 millionths indicator on an Indicol holder
clamped to the spindle collar and placed the probe on the
OD of the quill. A spring scale was clamped in the vise and
arranged to push on a rod held in a drill chuck. Cranking
the table allowed me to apply a controlled force while
monitoring deflection. I *may* have been able to see the
expected effect, but the deflections were much too small to
measure reliably - even with the force applied about 5"
below the spindle nose, a 60# load only moved the spindle
about .00015 relative to the quill. It *looked* like the
first .00005 occurred at about 10# load, but it'd take much
better resolution to be sure.

Interesting test. If I could figure out a way to take home
my federal electronic indicator, I could try that in the
hardinge. Of course, that may well have a preload spring
for the rear radial bearing, if Jim Schwitter's diagram matches
that machine.

Jim

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner