I want to thank everyone for the info. I spoke to a guy from MSC in
the Bridgeport parts dept. and he told me the bearing is Fafnir
JM-207-K DB/A-2729
I forwarded that info to the bearing guy and Im waiting to hear back.
Craig
PS Did you get my e-mail Gunner? I would like to know your method you
mentioned. Thanks
In article
snipped-for-privacy@novocon.net says...
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
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
================================================= please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
================================================
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
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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trauma,
but not humorist P.J. O'Rourke, who thinks the proceedings are a win-win
situation
-- and grand entertainment to boot.
Mr. O'Rourke, writing in the latest issue of the Weekly Standard, acknowledges
that
"some earnest souls have gone so far as to aver that impeachment
has distracted President Clinton from ... raising taxes, destroying health care,
appointing 1960s bakeheads to high political office, soliciting felonious
campaign contributions,
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secrets to the Chinese,
taking credit for the benefits of a free market about which he knows little and
cares less,
using U.S. military forces as fig leaves for domestic scandals and au pairs for
the U.N.,
leading foreign policy back into the flea circus of Jimmy Carterism, having
phone sex,
groping patronage seekers, and snapping the elastic on the underpants of
psychologically
disturbed school-age White House interns entrusted with the task of delivering
high-level government pizza."
Ouch. Tell us what you really think, P.J.
"No matter what, Bill," Mr.O'Rourke concludes,
"your girlfriend's ugly, your wife hates you, and your dog can't hunt."
--------------------------------------------------------------------------------
replying to Craig Suslosky, Steve523 wrote:
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.
replying to Craig Suslosky, Steve523 wrote:
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.
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