Clausing spindle bearings-help!

I'm restoring my 1963 Clausing 8520 mill ( pictures here if interested
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and in the process am replacing the spindle bearings. I've read through
many posts on the Yahoo Group and have just gotten more confused.
Talked to a few bearing "engineers" (ya right) at SKF and they don't seem to
have solid answers either.
The spindle takes a pair of 7205 angular contact bearings that are held in
place by a locking washer and nut. I was able to find on the MRC site that
the torque on the nut should be 23-50 ft-lb. but can't seem to find answers
to the following:
Should the bearings be mounted "face to face" (where the contact lines of
the bearings converge inward), or "back to back"?
I can order bearings that are ground and sold as a matching set in either "b
to b" or "f to f" that when mounted together and the retaining nut tightened
give a "light preload".
I can also order bearings that are not matched but are for "universal
pairing" that are about half the cost and are made to mount either way.
Some posts on the Yahoo Group mention that to apply a preload to these
bearings a shim is needed between them either on the inner or outer race,
others say none is needed. If the bearings are made to mount either way how
can they be preloaded without the use of a shim? If needed how thick should
it be?
The machine came fitted with standard bearings and no shims so I can't go by
what was there.
Any experts here? Thanks in advance!
Reply to
Terry Keeley
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Greetings Terry, I assume you have contacted Clausing asking them how to mount the bearings. If not, try, maybe they can help. They helped me a few years ago with questions about an Atlas lathe. I have spoken with both SKF and NTN engineers. Both were helpful. But I also had to go through some younger engineers to finally speak to older ones with more experience. You need to be able to tell the engineer how the bearings are mounted. The mount limits the options. The lines converging or diverging regulate the stiffness of the assembly. Try SKF again and insist, politely, to speak to someone who really knows. ERS
Reply to
Eric R Snow
Thanks Eric, you're right I'm sure, the person that was recommended at SKF was on the road for the week so I asked if anyone else could help...
Not sure about Clausing, posts on the Yahoo Group weren't too encouraging.
Reply to
Terry Keeley
Just out of curiosity, were the originals bb or ff? My first take on it would be to replicate the original setup.
If you do this without any shims the bearings will have way too much clearance I suspect. What bridgeport used to do was to grind the face of the bearing race to set this, rather than use shims, on the M heads.
My first take would be to order the same type (bb or ff) as the original bearings, and purchase them as a true angular contact pair.
Jim
Reply to
jim rozen
Almost certainly back to back.
You'll have to ask the bearing mfr for a definitive answer on the spacer thickness, but I wouldn't recommend this approach. A few tenths will make a big difference in the preload, possibly resulting in overheating or loss of rigidity, depending on whether the shim is too thick or too thin. Best to buy the proper matching set of bearings. A matched pair of precision 7207s should cost you around $275.
Ned Simmons
Reply to
Ned Simmons
.
Thanks for the help but someone installed regular standard ball bearings so I don't have any history to go by.
Think this might be the way to go also but most don't seem to go this route...
Reply to
Terry Keeley
Agree. When I was doing this with non-setup bearings I was taking a tenth off the spacers at the end while doing trials.
Jim
Reply to
jim rozen
Terry,
When I replaced mine I bought the bearings from Clausing as a match set. There was no shim needed/supplied). When I installed them I realized there was two ways to do it. I mounted them so that when they were mounted on the spindle they were "tight". I don't remember if I ever figured out if this was the official direction or not, but I never had any problems. This way make since to me because the spindle nut has a locking feature, and the retaining nut does not. If the nut backs off, then you have lost the preload (bad thing).
I did have a heating problem, but that was because I filled the bears completely with grease, and at the 2 highest speeds things over heated. Found out later that you should fill the bearings 1/3 rd with grease. Once I removed most of the grease it ran fine. You do this by filling 1/3 rd of the bearing 100% with grease, and then spinning the bearing around until it's even.
Hope this helps,
Vince
Terry Keeley wrote:
Reply to
Vince Iorio
Thanks for the help!
So when you put them on and tightened up the nut it applied the pre-load?
I'd hear tat about the grease, thanks.
Reply to
Terry Keeley
Terry,
Ask to speak with Jo(lene) Olds at Clausing, if she is still there. She's been pretty helpful to me in the past.
Mike
Reply to
Mike Henry
FWIW, the replacement bearings I ordered from Clausing a few years ago are Fafnir 7205WN SU. I haven't installed them yet, but it looks like it might be necessary pretty soon. There are one or two files in the Yahoo Clausing group that describe bearing replacement, I think. I've archived off two from there or elsewhere, complete with pictures. Email me if you can't find them at the Yahoo group.
Following is the only info that Clausing could supply me on the spindle (note that no "sample" was attached):
ASSEMBLING SPINDLE AND QUILL ASSEMBLY FOR CLAUSING MILL
1. Press 044-005 bearings one at a time on 701-004 spindle. Apply pressure on inner race only and use DB mounting as shown in instructions supplied with bearing - sample attached.
2.Slide 932-011 lock tab washer on spindle with inner tab in keyway.
3. Turn 537-020 nut on spindle and tighten securely against inner race of bearing. Bend a tab on the 932-011 lock washer into a matching slot of the 537-020 nut.
4. Place the spindle in the 631-001 quill - 044-005 bearings in the threaded end.
5. Press the 044-006 bearing on the spindle as far as it will go - apply pressure on inner race only and support spindle on nose only.
6. Assembly 708-001 oil seal in 641-008 retainer as shown in attached sketch.
7. Turn 641-008 retainer in quill -firm but not too tight.
8. Place M6-214 lead ball in threaded hole in quill and lock retainer with #10-32 x 3/16" socket set screw.
INSTRUCTIONS FOR REMOVING NO.8520-25 V-MILL SPINDLE ASSEMBLY
1. Remove (2) 1/4" socket set screws from No.537-014 knurled nut located on top of spindle, then remove knurl nut from spindle.
2. Remove (4) 1/4" machine screws (2 on each side of guard) which screws guard No.342-020 to head casting. remove guard by pulling forward.
3. Remove (4) screws which screws plate No.386-009 containing pinion and compound gears. Tap plate lightly on edge while prying outward with screw driver to remove from dowell pins.
4. Remove socket set screw in No.233-001 dial and lift or pry up on stop screw No.696-007 until top of screw is against spindle pulley, push quill to bottom position.
5. Remove 1/4-20 socket cap screw holding stationary stop to face of quill. With stop removed, remove quill assembly from head, reverse procedure to install quill. Caution --be sure when installing spindle pulley guard that brake lever is engaged in brake ring slot.
Reply to
Mike Henry
Thanks Mike, she's off having a knee replaced. Lee is the gal replacing her, she's semi-retired and good also but I didn't think they'd be good at this sort of thing...
encouraging.
Reply to
Terry Keeley
Well those instructions kinda confirmed what I've been hearing from others privately and also what an engineer at Barden said, it's back to back and there are no shims involved. Interesting they don't specify a torque rating for the locknut, I found that it's supposed to be 23-50 ft-lb. Thanks for the help!
Reply to
Terry Keeley
The true preload on the front pair is built in at the factory. The nut that tightens up the stack simply brings the inner races hard up against each other. The outer races have to be constrained to hard up against each other as well, this is typically done by placing them in a pocket with some kind of clamp ring that bears on the outer face of the outer bearing's outer race.
The bearing manufacture has them ground such that, as long as all races are tight up against each other, the preload (or, tiny amount of clearance) will be exactly correct. This is why true angular contact pairs are so much more expensive.
Jim
Reply to
jim rozen
Just curious, are those angular contact bearings? I can't find those numbers in the catalogue. The Fafnir numbers I'm getting are more like 2MM205WICRDUL, that's for a 25deg. Class 7 bearing.
Reply to
Terry Keeley
Once again, the torque on the locknut does NOT set the preload.
It only assures that the preload that is built into the bearings is achieved, and stays in place. Those things don't have to be honkin' tight.
Jim
Reply to
jim rozen
You've got me - I'm no bearing expert.
Based on the info in this link:
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It looks like they are a light duty (72), 25 mm (05), angular contact (WN) bearing, external self-aligning (S) - but no mention of what the "U" might stand for.
From the old Chaski group:
"By what I can find in my Fafnir bearing book a 7205WN SU bearing is a : Single row angular contact bearing 7200 series .. Light 7205 is the bearing size (25x52x15mm) WN is 37* contact angle and heavy-duty retainer of bronze SU is flush ground bearings for back-to-back, face-to-face, or tandem mounting
There is no description of this bearing being any type of precision (5, 7 or 9), the difference between this bearing and a standard 7205 bearing is the contact angle for combined thrust and radial loads.
I would see no reason that these bearings should not be replaced with the orginal specifications (bearing class), but the angular contact and being flush ground I would think would be very important. I would be cautious about replacing with a standard 7205 ($5 bearing). "
By someone else in response to a question about using standard 7205 bearings for the Clausing spindle.
Mike
Reply to
Mike Henry
Ive not removed bearings from your particular mill..but based on most angular contact bearings...they should be mounted like this " >> >to b" or "f to f" that when mounted together and the retaining nut
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Reply to
Gunner Asch
Call Alpine Bearing in Boston. Ask for JC..get his quote before buying from anyone else.
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Reply to
Gunner Asch
Gunner: Since when has that ever stopped you? Here's a P-38 C-Rat Can Opener, go for it... :-P
"Dumbth" needs to be stomped out wherever and whenever you find it. Even if you can't fix it, it's existence needs to become common knowledge so other people can spot and avoid it.
But give the company a heads up, a chance to figure out there's a potential problem with their old machines and to issue a service bulletin about it - if you get up on a soap box, they're liable to take offense and sic a lawyer or three on you.
A friend of mine (Not a FOAF) is a repair tech who found a repeatable flaw in an automated stage light - if you called for a certain combination of focus position, color filters and gobo screens, the whole light would lock up solid in whatever position it was in, and you had to remove power to get it to reset. If this happened in the middle of a show, it could be a big problem.
The company's initial reaction was to deny there was any problem at all, there's no way that could happen, yatta yatta yatta. Or at least till they tried it themselves - then they got very very quiet... They have since revised the operating firmware on the PROM two or three times, and AFAIK they send them free to anyone who asks.
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Reply to
Bruce L. Bergman

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