# Cutting Hardened Steel



## MattM (Aug 15, 2019)

I have a job that requires cutting a 1/16" retainer ring groove in a 1.5" hardened shaft.  This is at the end of a $600.00 part so I don't want to screw it up.

What's the best way to do it, or is it even possible?


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## matthewsx (Aug 15, 2019)

Tool post grinder in a lathe.

I did a similar thing with my Dremel tool cut-off wheel held firmly in my compound, though it was a smaller diameter and much less expensive part.

John


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## Asm109 (Aug 15, 2019)

How hard?


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## chips&more (Aug 15, 2019)

Sorry, not enough info. Like, just how hard is it? If you just want to play it safe. Then yes, grinding as opposed to tool cutting, would be the choice.


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## matthewsx (Aug 15, 2019)

Here's the piece I did before cutting the retaining ring groove. Chinese ballscrew so fairly hard part.




Tool like this.




John


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## MattM (Aug 15, 2019)

Don't know exactly how hard but a file skates over it and won't make an impression even when pressed hard.

 The part is a cluster gear from a tractor transmission.  The transmission is (now) designed to not require the retainer.  To use the new part without the retainer would require the purchase of an additional $2000.00 worth of parts.

The  "easy" solution is to cut the retaining ring in a new cluster gear.


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## matthewsx (Aug 15, 2019)

So you could go through three of these and still be under what it would cost otherwise? 

Assuming you have the lathe and a dremel you can rig something to your compound and try it out with a test piece. Once you're confident go ahead and do your part.

John


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## ezduzit (Aug 15, 2019)

If you don't have a toolpost grinder, either buy one or take the job to a machine shop that has one. I found mine on eBay,


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## Cadillac (Aug 15, 2019)

I would try putting jaw covers on your chuck to not scratch or marr your 600 dollar lead-screw. I’d use a reinforced cut off wheel or a carbide parting tool.


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## RJSakowski (Aug 15, 2019)

I would use a parting tool with a carbide insert.  My insert would cut a .080" groove.   If you use a grinding wheel, make sure that the load bearing side of the groove is not beveled.


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## Flyinfool (Aug 15, 2019)

What RJ said.
Using a Dremel and a cut off wheel will leave a radius in the bottom of the groove. Even with a tool post grinder it will be had to keep the corners square.
A radius in the bottom of the grove will allow the ring to easily pop off under load. It is surprising just how small of a radius can make the ring pop off. The sides of the groove MUST also be perfectly perpendicular to the axis of the the shaft. otherwise it is a ramp that will allow the ring to come off. Where I work we were having an issue with rings popping off under load. It took a magnifying glass to find the radius in the bottom of the groove. They sharpened the tool and all was good again.

Your best bet will be a carbide parting or grooving tool of the correct width with the sharpest corners possible.


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## bakrch (Aug 15, 2019)

I wouldn't even think twice about using a higher quality top-notch style grooving insert. We use .047 width in 50-55HRC 440C stainless and it has never been an issue.


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## RobertB (Aug 15, 2019)

depends on the hardness. If it's too hard for carbide, cbn would likely cut it, but the tooling will probably set you back more than farming it out to a well equipped shop.


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## matthewsx (Aug 15, 2019)

Thanks for the heads-up on retaining rings coming off, I never even thought about that but it does make sense. My application isn't inside a transmission so I'll see how my retaining groove works. If it gives me trouble I'll probably just upgrade the ballscrew to a NSK or something better than the Chinese one I have.

John


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## mmcmdl (Aug 15, 2019)

Topnotch grooving tool would do the job . I use them on Thompson Rod all the time . No problem .


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## MattM (Aug 15, 2019)

I think I have it beat.  Using the damaged piece to experiment I notched it with a carbide insert.  Once through I used a file to cut the groove.  

For the new part I'll buy a proper grooving tool.  What is recommended?

I borrowed a tool post gringer and will try that on the damaged piece tomorrow.

Thanks for the infor about the radius problem.


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## Cadillac (Aug 16, 2019)

Always look at the c-clip their is a ground side and a rounded side. Always put the clip ground side towards loads. The rounded side will also cause it to jump the groove.


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## ezduzit (Aug 16, 2019)

Cadillac said:


> ...Always put the clip ground side towards loads....



Negative. Always place the ground side AWAY from the loads. On second thought, perhaps I misread your post.


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## Cadillac (Aug 16, 2019)

ezduzit said:


> Negative. Always place the ground side AWAY from the loads. On second thought, perhaps I misread your post.



I think I miswrote it. You know what I was meaning. You want the ground flat surface to be on the load.


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## Chipper5783 (Aug 16, 2019)

Like Bakrch says - just cut it.  Carbide is really hard.  I've bored bearing inner races, I've cut a ball from a big ball bearing, I've cut the hard portion of HSS drill bits, I've threaded induction hardened shafting - the carbide does not last very long (the chips come off as tiny blue curls).  Make your set up as stiff as possible.  Should be no problem.  If it were me - I have a Top-Notch grooving tool holder, and I'd grind an old insert to whatever thickness was needed for said snap ring.

Let us know how you make out.


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## mmcmdl (Aug 16, 2019)

Chipper5783 said:


> If it were me - I have a Top-Notch grooving tool holder, and I'd grind an old insert to whatever thickness was needed for said snap ring.



Absolutely .


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## john.k (Aug 17, 2019)

Chipper5783 said:


> Like Bakrch says - just cut it.  Carbide is really hard.  I've bored bearing inner races, I've cut a ball from a big ball bearing, I've cut the hard portion of HSS drill bits, I've threaded induction hardened shafting - the carbide does not last very long (the chips come off as tiny blue curls).  Make your set up as stiff as possible.  Should be no problem.  If it were me - I have a Top-Notch grooving tool holder, and I'd grind an old insert to whatever thickness was needed for said snap ring.
> 
> Let us know how you make out.


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## john.k (Aug 17, 2019)

The proceedure for grinding a flat bottomed,square edged recess is a number of dressings of the wheel ,taking a tiny cut each time......the recess will end up perfectly square edged.


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