I'm replacing the spindle bearings on a mill I'm converting
from CNC back to manual, a Millport. I have two sets of
bearings collected from ebay, a set of Timkin and a set of
Barden bearings. Is there any real difference between the
two? I know they are both excellent names, but if there's
one better than the other, I'd like to keep it for my manual
Now, I got a small container of grease for the bearings.
Would like to know the proper procedure for greasing and
running in of the new bearings. Mill is a step pulley with a
2 speed motor and goes up to 5400rpm. I am pretty darn sure
I don't want to be running it full tilt right off the bat!
(and if anyone remembers, yes this is the mill I intended to
replace a couple years ago when I bought that Frankenmill
from Putterman on ebay. It's 'alive' again! Got a noisy head
I have to dig into, but otherwise it's living up to
I may be wrong but my understanding of Bridgeport spindle bearings is that
some later ones were sealed and the rest were open. The open bearings are
lubricated by oil which works down through the felt washer from the oil cup
on the top of the head. I do not think any manual Bridgeport spindle
bearings are supposed to be greased.
There is no "run-in" with antifriction bearings. What do you expect to
change in run-in? There is no wear allowance and if something does cause a
dimension change in the bearing(s), they are shot. If the bearings are
properly installed and lubricated, they should be capable of full load/full
speed right away.
I didn't quite state something right. I got a small
container of grease -with- the bearings, thus my assumption
that they were to be greased for initial lubrication. I know
they are not to be packed like wheel bearings, but I thought
a small amount was needed initially.
Ok, I need to really spell this out. I seem to recall
reading once about applying a small amount of grease to new
lower spindle bearings of a BP mill. This grease I assumed
was for initial lubrication, and that there was a run-in
procedure to allow the grease to be worked out of the way.
One was not supposed to run the spindle at full rpm until
the grease had been displaced. Running hot was a sign of too
much grease still in the bearing grooves. Perhaps I have
this info confused with lathe spindle bearings. That's why
I DO understand that spindle oil is the proper -ongoing-
lubricant for these bearings. Having small tubs of grease
shipped with both sets of bearings just reinforced that the
bearings needed this initial lubrication.
Run-in, again, refers to running the spindle at lower RPMs
until the excess grease has found it's way out of the way.
At 5400 rpm, this mill will run significantly faster than a
regulr BP step pulley. I also seem to recall that running
ball bearings too fast right after greasing can cause the
balls to stop rolling as the grease piles up in front of
them, causing them to skid, I would assume against the inner
race. This would not be good. This mill is being restored to
manual to sell, and I am touting the new spindle bearings.
It would not go over well with a buyer if he decided to go
run it flat out for a few hours on his first job, and ruined
the bearings. And no, I have not altered anything to get the
5400 RPM, it has a two speed, 2hp motor, and is so rated on
the data plate
SO.... if the grease is a bad idea from the get-go, are new
spindle bearings just installed and used? Should I at least
give them a small shot of spindle oil before installing the
spindle into the quill? Or do the bearings come with
sufficient lubrication to hold until the first shots of oil
reach them from the provided lube point? Having never
replaced spindle bearings before, I'm just looking for
advice and I hope I've cleared up exactly what I'm asking
ah...not true. super precision bearings such as lathe spindle
bearings DO need a run in, as life may be drastically reduced if you
run them full load from the git go.
Ive been called in enough times to repair the repair some maint guy
did on spindle bearings, and have talked to the hardinge factory, etc
etc many times...run ins are definately required on super precision
Most common bearings are NOT super percision..which is why you dont
need to run most in.
at yoyodyne they were all veterans of the psychic wars
exiled from the eighth dimension where the winds of limbo roar"
mariposa rand mair theal
I'm sure you are right, but I still want to know what happens inside the
bearing during run-in.
Are super precision bearings installed more loosely in their seats than
regular bearings so that they can move to accommodate minor misalignments?
I can't see anything else happening without ruining the bearing.
I can't tell you how much grease to put in it but you DO NOT pack it full.
These are not
wheel bearings. Too much grease on a high speed bearing can cause overheating.
it seems counter intuitive but trust me on this. Checking with the bearing
is a good plan. Kluber NBU-15
Here is a note I have in my palm.
Spindle Bearing Grease Kluber
Actually I doubt there is any lube system at all, per-se, for the spindle
Generically speaking, your grease is applied only at assembly, and "for
life", and it generally fills 1/3 of the total space between the balls at
the fill stage.
The Kluber nbu-15 will usually be the standard grease, ( expensive, yet
highly recommended)--and this grease is generally servicable up to 13k rpm
on 30 taper and to 10k rpm with 40 taper milling spindles, and it is rated
as being compatible with most any reputable bearing manufacturer's angular
contact class 7/ 9 spec's.
Mega ditto's on run in. Spindle bearings generally are run up to speed in
temperature, looking for rises. In the case of our lathes and id grinders with
spindles there is a specified proceedure with limits and steps. The 30k
air/oil mist lube.
Super precision bearings are not loose. There is a preload set by the housing,
spacers, and how the bearing was ground that depends on the application. They
loose by any means. Generally the preload is set by how the bearing is made. If
a super precision bearing it has a paper trail and certs behind it.
The run in is to get the grease uniformly distributed without
overheating anything in the process. We replaced the spindle bearings
on our Slant a year or two ago - two pairs of NTN high precision roller
bearings (about $1500 or $2000 total), and followed the run in procedure
from the NTN bearing catalog (which is on line if you want to do some
detailed reading). The grease fill was about 30% of the open volume of
the bearings if I recall correctly, measured with a syringe, and then
(roughly) we did 10 multiples of 30 minutes at speed, stop for 10
minutes, then go again, in 500 rpm steps from 500 rpm to max speed. At
each speed step the headstock got noticeably warm to the touch the first
time, then by the tenth repeat of that speed it had cooled down to
barely warm. Took many hours to get it done but afterwards the
headstock always stays cool and we didn't cook or melt the grease out or
ding the bearings like we were warned could happen if we skipped the run
Carl Ijames carl dott ijames aat verizon dott net
(remove nospm or make the obvious changes before replying)
Carl and Wes,
Thanks for the posts, and thanks Gunner for the phone
support! I was pretty sure I was on the right track here.
I don't know what grease was supplied, but was told it was
formulated for these types of bearings. It's red in color.
Bearings are packed (not fully!) and the quill is ready to
reinstall. Sure feels a heck of a lot better!