Hi Arch

I've made this comment before, that a car or truck can go down the
road at 70 MPH or more, keeping al that weight up while hitting bumps
and ruts, and doing this day after day, while in most cases no one
ever takes a second look at them.

Then when someone wants to hammer an essentially sharp object into a
soft medium (wood), cries are heard, that one is destroying the
bearings by doing so.

Ever looked at the hammer drill people use, those iddy biddy bearings
get whacked a thousand times and just keep on ticking.

Running a bearing at high speed with constant high side pressure,
developing high heat will ruin a bearing much faster, even that will
take some time to happen, as first the lubricant will run out or
degrade, and than the frictions will get higher and the head
ultimately will destroy the bearing.

With lathes the biggest problem IMO is the cheaper bearings used, with
only shields in them, that do not keep out the dust and grit, those
will die untimely, not by driving a wooden stick onto a sharp spur,
and that is my opinion.

Have I damaged bearings ??, yes I'm afraid so, I do confess to have
hit large ball bearings with a sledge hammer to get at the balls, we
played games with them, when my Dad found out, he was not impressed,
I do remember that.

Don't remember what the bearings came out of, it was wartime material,
and the bearing balls where at least an inch in size as I seem to
recall.

Have fun and take care
Leo Van Der Loo


On May 6, 5:25 pm, (Arch) wrote:
Over the years,I've read and heard repeated warnings by various experts
that driving a blank onto a morse tapered spur center while it's on the
lathe will damage the bearings. It would of course, damage an obsolete
outboard cup (---point thrust bearing, but I wonder about the ball
bearings used on woodturning lathes of the sizes and types that most of
us use.

The warnings must be true, but for me it seems I have a mild case of
Charlie's bumble bee syndrome. Maybe I've been lucky not to be stung
yet, but I've driven many blocks onto MT spur centers while inserted
into the spindle and haven't heard that ominous rumble yet.

I can see that if a spindle is axially free except for being locked onto
the bearings, banging it axially would damage the
bearings. Are the spindles of most of our lathes attached to the
bearings tightly enough to cause damage by axial pressure? Not
according to the instructions for removing the spindle from some popular
machines. I'm _not talking about cartridge, roller, angular, etc. types.

If the spindle is restrained by collars or pulleys and floats fairly
easily thru the bearings why is the bearing damaged?. What part of the
_bearing (forgetting spindle, pulleys, bearing seats and castings) is
damaged by seating a wood blank onto a spur center that's already in the
spindle taper? I'm often wrong. What am I missing this time?

Have any of you damaged bearings by illegally banging an innocent blank
onto a spur center while it's in the spindle taper?

Turn to Safety, Arch
Fortiter

http://community.webtv.net/almcc/MacsMusings