# Question about Clausing 8530



## Tink (Nov 9, 2017)

Hi
I have a number of questions regarding the 8530.  Anyone know who manufactured and the model number of original  lower spindle  bearings ?  Seems to be some conflict. I've seen pictures of fafnir 7205wn su from Clausing  but from the bearing people that I talked to they were never made in a matched pair. Another website said they installed SKF7205byg which I cant seem to find. Wentstech site said they were matched pair bearings. Some one else said the bearings that came out of their unit was New Departure 30305. So if Clausing is selling the Fafnir 7502wn su what is the difference between the original and what Clausing is pushing. 

Anyone have a knee handle, X power feed, or the fast feed handle for the x-axis they are willing to part with? 

If I run my spindle at high speed for 15 minutes the quill gets a little warm anyone else have that issue. The spindle sounds fairly quiet.

Thanks


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## Bob Korves (Nov 9, 2017)

Tink said:


> If I run my spindle at high speed for 15 minutes the quill gets a little warm anyone else have that issue. The spindle sounds fairly quiet.


"A little warm" is not an issue, it is normal.  HOT and running away is a big issue.  If you can hold your hand on the quill after running the machine hard for a while, all should be well.  Excessive heat is usually from bearings packed too heavily with grease (if greased bearings are appropriate) or from excessive bearing preload, which can be reset per the mfg. instructions.


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## wa5cab (Nov 9, 2017)

Call Clausing and ask them.  They made it and there might still be someone around who remembers.


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## wa5cab (Nov 9, 2017)

What does "matched pair" mean in terms of ball bearings, anyway?  I've been sitting here thinking about it and can't think of anything akin to matched pairs of V-belts, for example.


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## Briney Eye (Nov 10, 2017)

wa5cab said:


> What does "matched pair" mean in terms of ball bearings, anyway?  I've been sitting here thinking about it and can't think of anything akin to matched pairs of V-belts, for example.



They're angular contact bearings.  The faces can be ground to apply a preload to press the balls against the races when the bearings are tightened against each other, making them stiffer.  The grind has to be very precise, since the clearances are so small to start with.  Usually they're just ground so that the inner and outer races are flush, so no preload is applied.


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## ConValSam (Nov 10, 2017)

I replaced the spindle bearings in my 8520 (same head as an 8530) and the attached documents proved very helpful when I went to it.  I think both came from the Wentztech site, but can't remember.

I think the reason you can't find the SKF bearing is because there is an error or omission in the P/N used in Fred's writeup.  I concluded the proper bearing was SKF 7205 BEGBY.  B = 40° contact angle E = Optimized internal design GB = Bearing for universal matching. Two bearings arranged back-to-back or face-to-face have moderate preload Y = Stamped brass cage, ball centred.  Quick search found them in stock at Zoro for $75 each.

Hope this helps.


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## Tink (Nov 10, 2017)

ConValSam said:


> I replaced the spindle bearings in my 8520 (same head as an 8530) and the attached documents proved very helpful when I went to it.  I think both came from the Wentztech site, but can't remember.
> 
> I think the reason you can't find the SKF bearing is because there is an error or omission in the P/N used in Fred's writeup.  I concluded the proper bearing was SKF 7205 BEGBY.  B = 40° contact angle E = Optimized internal design GB = Bearing for universal matching. Two bearings arranged back-to-back or face-to-face have moderate preload Y = Stamped brass cage, ball centred.  Quick search found them in stock at Zoro for $75 each.
> 
> Hope this helps.



Let me see if I'm learning anything here. Those bearings didn't come as a matched pair correct? Because they are universally matched. I see they have a ABEC 3 rating. The fafnir 7502wn su are some what the same but are ABEC 1. I think the u means universal on the Fafnir bearings.  So how did you define moderate preload when  you installed them?
I haven't had mine apart yet

Thanks


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## wa5cab (Nov 11, 2017)

Briney, thanks.

Sam, why don't you put the two files into Downloads?

Tink, from Fred's write-up and drawing, it appears that the designed preload will be achieved when the initial gap between the two inner races is reduced to zero.

BTW, you guys need to set up your Signatures.  You do this by clicking your User ID in the top tool bar, and then clicking on Signature in the small window that will appear.  If you click on Account Details in the same window, you can upload a photo to use in place of the default first letter of your ID for your avatar.  Note that there is a character count limit in Signature based on your status (Registered Member, Active Member, Donor, etc.).  But I don't recall the numbers.


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## ConValSam (Nov 11, 2017)

Tink

First, I only play a bearing expert on the interwebs....

The specification creates the "matched" pair; If you purchased 7205 BEY, the manufacturer has not tested the bearing to confirm how it preloads in a set.  One might still achieve the proper load in a pair, but it would by chance and not be by numbers.  Like any manufactured product, there is a range of tolerated variance to the bearing.  7205 BEGBY have a tighter tolerance for preload in a pair.  The tighter tolerance also makes a difference in the price: SKF 7205 BEY are only $50 each.

wa5cab is correct about the preload.  I would add that there is a little bit of a _feel_ factor to bearing preload.  You can't see the two inner races once the bearing are pushed together.  One must tighten the lock nut and then test the rotation / axial slop to determine when it is right.  If the bearings don't turn, it's too tight.  If the outer races shake to and fro - too loose.  Think Little Red Riding Hood.

wa5cab

Thanks for the suggestions.


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## Briney Eye (Nov 11, 2017)

The only bearings that I didn't replace in my 8520 were the spindle bearings and the thrust bearing in the knee, because they seem to be in pretty good shape.  But I've been looking at all the flavors of 7205's just the same, trying to figure out what I would get if I needed to replace them.  The tip about BEGBY (and verifying it on SKF's web site) prompted me to go ahead and buy a couple on eBay.  Came to $102 with shipping.  I already have the top bearing.

So sometime soon I'll be tearing the head down again.  I figure I'll replace the bearings every 50 years whether they need it or not.


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## Briney Eye (Nov 11, 2017)

I thought I would throw this in for the benefit of people replacing these bearings in their Clausing mills.

There are a couple of illustrated guides out there for tearing down the head.  One thing that I noticed was that they had some difficulty with the bottom oil seal retainer, which requires a spanner wrench.

The spanner that I used to remove the retainer can be had for $10 from Amazon, and is made by Park Tools for bicycle bottom brackets.  The pins are the right size, and it only has to be spread a little bit to engage with the retainer.  It's a little short, leverage-wise, but it worked fine for me.  If your retainer seems really tight, I highly recommend Kroil and patience.

Oh, and I picked up the oil seal from eBay.


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## ConValSam (Nov 11, 2017)

++ to purchasing a commercial spanner.  Or spending the time to make a quality tool in the shop.

I spent more time fussing with the one I made from an old pair of slip joint pliers and two spent drill bits than I care to admit.  Further, because the seal seat is not hardened, a lousy setup can mangle the holes.


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## calstar (Nov 11, 2017)

"The spanner that I used to remove the retainer can be had for $10 from Amazon, and is made by Park Tools for bicycle bottom brackets. The pins are the right size, and it only has to be spread a little bit to engage with the retainer. It's a little short, leverage-wise, but it worked fine for me. If your retainer seems really tight, I highly recommend Kroil and patience.

Oh, and I picked up the oil seal from eBay."

Pic of tool in action on an 8530:


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## GrizzlyBagWorks (Nov 21, 2017)

I purchased a set of Timken _ 2MM205WI DUL when I did my rebuild but found that I was able to use the stock bearings after a thorough cleaning and regreasing.   They were not cheap.  Were I to do it over again I'd buy these: _

https://www.ebay.com/itm/NSK-7205CT...797191&hash=item2844ddda67:g:GdwAAOSw1DtXJSRz


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## calstar (Nov 21, 2017)

GrizzlyBagWorks said:


> I purchased a set of Timken _ 2MM205WI DUL when I did my rebuild but found that I was able to use the stock bearings after a thorough cleaning and regreasing.   They were not cheap.  Were I to do it over again I'd buy these: _
> 
> https://www.ebay.com/itm/NSK-7205CT...797191&hash=item2844ddda67:g:GdwAAOSw1DtXJSRz



This info needs to put in a sticky, Clausing generally charges prices way above other vendors for similar bearings. In the case of the spindle bearings they do not offer matched pairs, but the price is still really high.  

Thanks for posting this,

Brian


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## wa5cab (Nov 21, 2017)

Their prices are better if you don't live in California.  To get a true picture, you should get someone who doesn't to call them.


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