Proper greasing and run-in of new spindle bearings?

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 Bridgeport.
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!
Anyone?
Thanks,
Jon
(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 expectations)
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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.
Don Young
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They arew supposed to be oiled with spindle oil. (!)
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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.
Gunner?
Jon
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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. I know, it seems counter intuitive but trust me on this. Checking with the bearing manufacturer 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 bearings proper.
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.
http://www.kluberna.com /
HTH, Wes
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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.
Randal
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Randal O'Brian wrote:

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'm asking?
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 and why.
Thanks,
Jon
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On Tue, 17 Jun 2008 12:15:21 -0500, "Randal O'Brian"

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 bearings.
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
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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.
Randal
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Super precision bearings are not loose. There is a preload set by the housing, the spacers, and how the bearing was ground that depends on the application. They are not loose by any means. Generally the preload is set by how the bearing is made. If you have a super precision bearing it has a paper trail and certs behind it.
Wes
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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 in.
-- Regards, Carl Ijames carl dott ijames aat verizon dott net (remove nospm or make the obvious changes before replying)
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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!
Jon
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Did you line up the run out marks? Usually an o or dot that shows maximum runout. you want all the bearings dots lined up.
Wes
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Wes wrote:

Yep!
Jon
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Doing good!
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Mega ditto's on run in. Spindle bearings generally are run up to speed in steps, checking temperature, looking for rises. In the case of our lathes and id grinders with 30k spindles there is a specified proceedure with limits and steps. The 30k spindles are air/oil mist lube.
Wes
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