# Turning Tapered Bearing Races On Chinese Lathe



## 62Scout (Nov 17, 2016)

Spent the weekend rebuilding the front axle of my Suzuki Samurai, which included replacing all the bearings.  Went through my usual rigamarole of using a hammer and drift to knock the old races out of the hubs, and found my bearing driver set didn't have a driver that matched the bearing size I was using.  

No big deal - just grind down an old race to just under the diameter of the hub bore, and use it to drive the new race in....and oh, hey!  Good use for my lathe!  Chucked that sucker up, and promptly ripped the edge off a tool bit.  Oh yeah...duh!  I learned this 20 years ago - can't use HSS to machine hardened steel.  

In the interest of finishing this miserable job right then, I did a big no-no, and used an angle grinder on the race while still chucked up in the lathe and made it work.  

But it got me thinking for the future, in case I run into this again.  From reading here, it appears that I can use carbide tooling to machine hardened steel, but what do I do in the case of not knowing what the material is (beyond steel of some sort), or what type/depth of hardening it is?  In this case, I couldn't care less what the surface finish is like...seeing as how an angle grinder produced a satisfactory part, lol.  I just needed to pull a few thousandths off the OD.  Is there some kind of "universal" carbide tooling I can get that won't cost a small fortune for something I may or may do again in the future?


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## Bob Korves (Nov 17, 2016)

Tool post grinder.  It will do lots of other work as well...


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## Wreck™Wreck (Nov 17, 2016)

Hard Turning inserts (CBN), I often turn the shanks of taps and end mills for clearance in mill operations, also do a recurring job on hardened steel automotive drive line components.

When they say do not use on steel under 48 HRC they mean it, this will destroy an insert immediatley.

Expect lots of sparks.

http://www.sandvik.coromant.com/en-...aterials/hard-part-turning/pages/default.aspx


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## Tony Wells (Nov 17, 2016)

Likely the material is E52100 upwards of 60Rc. You will need either ceramic of some sort, or CBN. BUT, if you are installing new races, I would never recommend using a hardened driver. Get something softer.


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## kd4gij (Nov 17, 2016)

I  made a set of bearing and seal drivers out of mild steel years ago Used them in a shop every day for 10 years. still look the same as when I made them.


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## stupoty (Nov 17, 2016)

you could probably anneal the race to make it a little easier to machine, should still be good for pushing the new bearing in as the compressive strength shouldn't change.



kd4gij said:


> I  made a set of bearing and seal drivers out of mild steel years ago Used them in a shop every day for 10 years. still look the same as when I made them.



I've used aluminum for pressing in wheel bearings with good results, in fact I had to use a larger threaded rod size as the first one I used necked then had a ductile fracture  fairly tight fit I guess.  I've normaly would make press plates from steel but I just didn't have the diameter of steel available.

Stuart


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## bfd (Dec 9, 2016)

good advice above do not hit hardened against hardened the resulting chips can come off very fast and penetrate the skin. using a hand grinder on the lathe is not the best thing but with a little precaution you can lessen damage. clean off oil from your ways. cover everything with rags. carefully remove rags when done clean off all dust reoil ways and clean under wipers if your lathe has them move carriage  away from chuck then wipe down again reoil and move carriage towards chuck move away again and reclean and oil again. buy the way you should do this with the the tool post grinder also as it puts off grinding wheel particles and grinding dust. bill


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## David S (Dec 9, 2016)

I made a tool post grinder out of a spare rotary tool.  Simple and price was right.




David


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## ELHEAD (Dec 9, 2016)

Scout, More than once ran into the same problem, having a wood lathe I turned mine from oak.  Even small pieces of fire wood work great . Country boy has to do with what he has.
David


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## Tony Wells (Dec 9, 2016)

Yup, hardened steel on hardened steel is a no-no. I have a small piece of steel in my right bicep to prove it. Just glad it didn't go for the eyeball. Used a claw hammer (carpenter style) on a hard drawbar on a #4 Cinn mill. A small piece broke off and embedded in my arm. Thought it was never going to stop bleeding. Guess that ought to be in our "mistakes to avoid" thread.

Carpenter's hammer are hard, nails are soft. Mechanics hammers soft, car parts are hard.


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