B`port bearing update

In article , snipped-for-privacy@novoc> I want to thank everyone for the info. I spoke to a guy from MSC in That doesn't sound right. A Fafnir 207K is a deep groove ("Conrad") radial bearing. According to a 1966 BP manual (that has Fafnir numbers in it) the upper spline drive bearings are 207Ks.
The lower spindle bearings are angular contact bearings. Why aren't you just buying them from MSC?
Ned Simmons

Ned, These are the bearings listed in the B`port parts section. They look like a radial ball bearing, but have "thrust" stamped in the outer race. I tried giving the guy the #`s off the bearing, but he needed more info. I probably will get them from MSC if I can`t find another source. They are a little pricey, but if I got to, I will buy them there. I`m waiting to hear back from Gunner, he has a source that he believes will be a little cheaper (for the same bearing, not an imitation) Is the agular contact bearing the same as a roller,instead of ball, bearing? Isnt a car wheel bearing an angular contact? Or do I have them mixed up? Craig

No a car bearing is a tapered bearing.... the bearing you seek are ball bearings... see my post to the original thread for more information...

Car wheel bearings -- at least conventional style -- are tapered roller bearings.
Normally, "angular contact" referrs to a ball bearing with the geometry of the races arranged to accept significant axial (thrust) load or preload. Used as a pair to preload each other in a spindle application, they can be made to be very stiff in the radial direction.
Mill

No. Tapered roller bearings and angular contact ball bearings are two different animals.
Angular contact ball bearings are typically two bearings, manufactured as a matched pair, that are supposed to be run with the outer and inner races in contact with each other. Hence the "thrust" engraved on each of the outer races.
When they are mounted that way the balls contact the outer races on one side, and the inner races on the other.
Imagine a bicycle hub - when the cones are tightened down the correct amount, the balls touch the outer races on the inside, and the cones on the outside. One pair of ball bearings, but when preloaded properly they become quite rigid.
The manufacturer grinds the faces of the bearings to set the preload properly so they load up the correct amount when in contact.
But they are invariably ball bearings.
Bridgeport used to set these up themselves on the M head using standard 205 bearings, they would trim the race surfaces to get them to load up with spacers in between inner and outer races.
Jim
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Did you miss my earlier post, Craig? Here's the text again,
************************* The bearings are class 7 "angular contact" bearings. Motion Industries shows 154 of the the Fafnirs in stock. The others listed below are equivalents. FAFNIR 2MM207WI DUM NSK 7207CTRDUMP4Y SKF 7207 CDP4A DGB BARDEN 207 HDM BRG
Order a qty of 1 and you'll get a pair matched with the proper preload. Expect to pay from $275 to $300 for the pair from a bearing distributor.
The top bearing on hte spindle is a 6206. I replaced mine with an SKF 6206 CN - the CN specifies no internal looseness, other mfrs may use C0. Less than $10. I think the original was a higher class bearing, but bearings are so good these days I doubt you'd be able to tell the difference for the upper bearing.
***************************
Angular contact bearings look like regular radial ball bearings at first glance. If you look a little closer you'll see that the races are asymmetrical - one shoulder of the race is higher than the other. They excel at carrying combined thrust and radial loads (much like tapered roller bearings) so are often found in machine tool spindles.
I think wheel bearings in front wheel drive cars are often angular contact bearings, but someone else can probably tell us for sure. Angular contacts are ball bearings, not tapered roller bearings.
I've never seen one stamped "thrust" like yours, perhaps it indicates the direction that an axial load should be applied to the bearing?
Re the price, IIRC Motion Industries quoted me $235 for the pair when I rebuilt my spindle about 2 years ago. Looking online now they're telling me my price is $275, but the online prices are sometimes flaky. They treat me pretty well, so I think you can use the $235 number as a benchmark. I'd be curious to know what Gunner is able to do.
Ned Simmons

Emailed to Craig
Gunner
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The machine uses angular contact bearings and they should be purchased in a matched set with the ground spacers. I purchased a set from a local bearing dealer for 275.00.
Charlie

I am rebuilding two J heads right now and none of them have the angular race bearings, two have the bearings that you specify here, the one head I finished a while back I don't remember if they were Fafnir, but they were not angular race either. Angular race would be good to have because they handle side loads so much better. I have 4 rebuilds so far and the first one I did years ago ran fine on the regular radial bearings until someone "adjusted the ways" and broke it and they decided to send it to salvage (big mistake). Anayway, I guess what I'm getting at, is these bearings run true and they run fine enough for any of the work I've seen them do.

I am rebuilding two J heads right now and none of them have the angular race bearings, two have the bearings that you specify here, the one head I finished a while back I don't remember if they were Fafnir, but they were not angular race either. Angular race would be good to have because they handle side loads so much better. I have 4 rebuilds so far and the first one I did years ago ran fine on the regular radial bearings until someone "adjusted the ways" and broke it and they decided to send it to salvage (big mistake). Anayway, I guess what I'm getting at, is these bearings run true and they run fine enough for any of the work I've seen them do.