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[4]

What tooling to turn a case hardened Chevy axle

[3]
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outsider347

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#1
Now that I have a better lathe ...PM 1236, I want to turn a couple Chevy rear axles that I have in stock
I did also move up to index able tooling , CCMT 300 series inserts that I also bought from PM
I am sure that the axle shafts a case hardened...had to cut them with a cut off wheel

Suggestions appreciated.
Tks Gents
ed
 

cathead

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#2
Case hardening is generally done to mild steel to make a few thousandths of the outside hard by
soaking it in a hot and carbon rich environment and then quenching it in oil. Axel shafts are generally
made of a hardened version of 4140 steel or close to that. You can soften an axle up considerably
by heating it up red hot and allow it to cool slowly in a fire. I have done this several times when I
want to machine on an otherwise very hard truck axle. A wood stove works great for this. IMG_0614.JPG


Note: You can see the end of the axle in the middle between the two logs. They are very machinable
after being in the fire. I use carbide to machine on this but I would think even HSS would work.
 
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Wreck™Wreck

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#3
Hard turning inserts, find an insert that fits your holders and have at it, I do it several times per month on automotive driveline components, works a charm and gives an excellent finish. Try not to go very far below the case as soft steel will play hell on some insert material.
NO COOLANT and the chip should come off glowing red so do not leave anything in the pan that will catch fire easily such as POM or PE.

https://www.sandvik.coromant.com/en...ning-in-different-materials/hard-part-turning

 

benmychree

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#4
Axle shafts are more likely induction hardened than case hardened; the hardness can go quite deep; evidence of induction hardening can be seen on some axles by heat colors likely on the ends.
 

Ray C

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#5
As others have mentioned, axles are are not case hardened. They are typically made of 4142 and hardened way up there in the 58 RC range. The annealing temperature for the chromalloy steels is 1600 to 1650F. You need to hold it at that temperature for 30 minutes for each 1" of cross-section followed by a 12 to 15 hour gradual cool down below 350 F. That will bring it down to about RC 25 which is very workable.

Your machine is a good one (I have the same machine) but, it's not really the best choice for "hard machining". I can and have done it using ceramic inserts but generally, avoid cutting metal that hard. It's tough on the machine. The only time I do that kind of work on my machine is for very small adjustments on simple features. A more suitable machine for "hard machining" is something in the ultra-rigid class with a 7 to 10 HP (or greater) motor.

You could also bring the piece up to about 1000 F, until it's saturated at that temperature then, let it cool down in the oven with the door vented over 12 hours. That will temper it down to about RC 40 which your machine can handle if carbide inserts are used.

Ray
 

f350ca

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#6
I've used a couple of truck axles for shafting. Some cut reasonable with carbide, some eat anything you put up against them. Those ones get tossed as they cost nothing in the first place.

Greg
 

Chipper5783

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#7
It sort of depends on what you are doing. If the final product can be soft, then anneal as described by others above. If you want it hard, then it is no big deal to hard turn as has also been described above. If you are just doing a few pieces, then most any carbide, speeds, feeds - will be fine. If you are going to do quite a bit, then get some inserts designed for that application.

I have annealed axles and found that they turn out almost "gummy" soft. I've turned axles in the hard condition and you get a beautiful finish, just tough on the inserts.
 

4GSR

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#8
1600-1650 is a bit too high on temperature, that is your Normalizing range. Material will be very gummy to cut and dead soft. 1450-1550 degree F is your annealing temperature range. Just do like Ray said at his last statement, temper at about 1000 degree F. That should get you in the high 30's HRC. IT'll cut nice and sweet with the right insert or even HSS with a ground in chip breaker.
 
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fitterman1

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#9
CBN or Diamond tipped (as used in the video)
 

fitterman1

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#11
I see a PCD tip in the video above so there must be some merit to using it. Most people would use CBN because it handles much higher temperatures than diamond, but for an axle I think either one should be ok.
 

outsider347

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#12
Tks for the suggestions
I will be out of town this weekend returning Monday to work on this proj
I will LYK the result
ed
 

Chipper5783

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#13
I see a PCD tip in the video above so there must be some merit to using it. Most people would use CBN because it handles much higher temperatures than diamond, but for an axle I think either one should be ok.
An axle, even in the hard condition, is not a big deal. Most any carbide will cut it just fine. Sure, if you had quite a bit to do and wanted to optimize the cutting process you would investigate what type of tooling, speeds, feeds etc.

Regular carbide is really good stuff, very hard and also a pretty tough material. I've cut HSS in the hard (as in the flute portion of drill bits), I've bored the ID of bearing races - I didn't sweat the type of carbide. The work has to be held as rigidly as possible and edge of the insert dulled in just that job - but it was only one edge of the insert and got the job done.

I've never used PDC or CBN - I'm sure it is a good material.

Let us know how it works out. David
 

Downunder Bob

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#14
I've never heard of a car or truck axle being case hardened they should be through hardened to be tough more than hard. I have cut quite a few on my band saw using HSS blade, just use slow blade speed and keep the feed up a bit. I've also turned them with regular carbide, no problems, and even used HSS but you must keep the speed well down, it will cut.
 

jdedmon91

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#15
Hard turning inserts, find an insert that fits your holders and have at it, I do it several times per month on automotive driveline components, works a charm and gives an excellent finish. Try not to go very far below the case as soft steel will play hell on some insert material.
NO COOLANT and the chip should come off glowing red so do not leave anything in the pan that will catch fire easily such as POM or PE.

https://www.sandvik.coromant.com/en...ning-in-different-materials/hard-part-turning

Yes they make CBN inserts that I used at my day job for at least 20 years to turn bearing journals for shafts. Of course it was a CNC lathe holding +_.00025


Sent from my iPhone using Tapatalk
 

toploader

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#16
I had to machine down some 1.5" 4340 aftermarket axles shafts recently the inners were .385 to long. I put them in the vise on the vertical mill and used a 1" solid carbide endmill. Made quick work of them.
 

mickri

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#17
I am resurrecting a 1966 MG Midget. Because I am swapping in a Toyota 3tc engine and 5 speed which has a little more horsepower and torque than the stock motor it is recommended that I slightly modify the axle shafts. The modification is called growlerizing the axle named after the man who popularized the modification on the midget forums. The axle shafts are made out of EN17 steel. I have no idea what type of steel this is. I was planning on using HSS.

More background info. Midget axle shafts are notorious for breaking at the inboard end. Especially the early ones made out of EN7 steel. The axle housings flex and over time this flex creates what is referred to as a hard spot where the outboard end of the female splines in the differential rest on the male splines on the axle. This typically occurs about 1.25" in from the inboard end of the axle. The modification is to turn down the axle starting 1" in from the inboard end to the root diameter of the splines for 4" and then taper the axle over the next 6" back to the original diameter. See sketch. Stock axle on top and growlerized axle on the bottom.

spridget axle.jpg
How should I go about doing this on my craftsman 12x36 lathe? I was planning on turning the axle between centers. I believe that the axles have center indents (wrong term??) on each end. I also have a 4 jaw chuck that could hold the outboard flange end and use a live center in the tail stock at the other end.
 

mickri

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#19
I have a tool post grinder that came with my lathe. Might need a new wheel or at a very minimum to be dressed. The thing is a beast. Has to weight 50 lbs or more. So that is a possibility.
 

Glenn Goodlett

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#20
Way off topic, but when I was much younger I had an MG Midget that I put a 2.0 liter fiat motor and 5 speed in. If I dumped the clutch and the wheel started to hop, It would break an axle like nothing. I got to where I could swap axles in half an hour on the side of the highway. I never heard of the mod you mentioned. Didn't have a lathe at the time anyway.
 

mickri

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#21
From what I have heard on the midget forums growlerizing an axle was well known to the racers for quite some time. It just never trickled down to the masses. Also the early axles made out of EN7 steel weren't very strong to begin with. Rumor has it that one of the main reasons for changing the rear wheel arch from round on the bugeyes to square with the new body style was to prevent the crazy Americans from stuffing big wheels and tires on the cars to prevent axle breakage.
 

Glenn Goodlett

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#22
My run with British sports cars was well before forums and the internet so I'm not surprised it didn't trickle down to me. And of course my rear fenders were cut with flares added to stuff big wheels and tires on the thing. There is NO way I could even get my fat ass in a Midget now days.

Can you insert the axle through the spindle so that your not working on such a long part? If not I would expect you would probably need to use a steady rest to hold the axle rigid enough to turn it down. I don't know anything about a craftsman lathe.

I would use an indexable turning tool with a TiAIN coated insert or similar running at about 900 rpm with a feedrate of 2 ipm and 0.050 doc. My software shows this at 360 sfm and 0.0022 ipr requiring about 1 hp.
 

mickri

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#23
I barely fit in a midget and I am only 5'10". I don't know how the taller guys do it. Has to be pretty uncomfortable. I am not doing a major fender cut out with flares. Just removing the inner lip. I am working on the driver side right now.

Thanks for the suggestions. The axle won't fit through the spindle. I do have a steady rest and a follower rest. I have never used the follower rest. I frequently use the steady rest even when I probably don't need to. My Craftsman lathe runs at slower speeds and being a newbie I tend to turn at very slow speeds. Turning the taper is going to be a challenge. The only attachment that didn't come with my lathe was a taper attachment. I'll figure something out. Probably do the taper in sections. The compound has just over 2" of travel.

Being retired and having nothing but time on my hands if it takes me several days to do something that's ok. My garage shop is not air conditioned. And with other daily chores on my 5 acres and taking care of my elderly mom who just turned 100 I can spend about 1 hour per day in my garage before the 95 to 100 degree summer temps drive me into the house.
 

Bob Korves

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#24
I was 6' 1", now 6' even, so I had a MGB... Plenty of leg room.
Edit: we are far off topic.
 
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