is 52-58 HRC machinable?

[The Cobbler]

looking at re-purposing a masons chisel into something else. need to turn the hex down to round. I hit it with a file and it grabbed a bit. the specs say 52-58 HRC .
am I nuts thinking I can chuck the chisel end in a 4 jaw , center drill the the shaft and turn the hex down?
here's a link to what I am thinking of starting with ( with the hand guard removed) https://www.princessauto.com/en/detail/3-1-2-in-mason-chisel-with-guard/A-p8548463e

 

[rlitman]

Why not grind?

 

[The Cobbler]

I could. I want reasonable precision. want to make a chisel for my air hammer .
I could mount it in the lathe & grind it for sure. even by hand would probably get close enough . good idea. tks

 

[Monza Harry]

The hammer end should have been annealed, 52 rockwell C is pretty hard and would be prone to chipping with repeated hammer blows, and a file will only be scarred (ruined) by that hardness. I would figure that end to be between 32 and 40Rc quite machinable even with HSS with some care and patients [with a good coolant bath as you approach 40Rc]. Carbide won't even know it is cutting at that hardness. Harry

 

[dr_clyde]

What kind of lathe do you have and what kind of tooling?

I wouldn’t attempt this with an Atlas with HSS tooling, but a rigid industrial machine with carbide should cut it fine.

Anything is machineable if you have the right tooling.

 

[The Cobbler]

Standard Modern 1334 lathe.1-1/2HP , carbide & HSS tooling . no coolant pump .

 

[Monza Harry]

Standard Modern 1334 lathe.1-1/2HP , carbide & HSS tooling . no coolant pump .

Carbide it is then! Harry

 

[The Cobbler]

Thanks . hope to get to it in a few days. got a project that I want to use it on.
light cuts at first then heavier when the hex is turned round?

 

[zkling]

Thanks . hope to get to it in a few days. got a project that I want to use it on.
light cuts at first then heavier when the hex is turned round?

Depends on your lathe and the insert (if using an insert). IF the machine is capable it is typically best to get to a uninterrupted cut (below the hex) in one shot.

I don't know what your exact goal is, but....I wouldn't waste my time of trying to make a masons chisel into an air hammer bit. AND I have the proper equipment to do so.

https://www.amazon.com/dp/B07H92F2XM/?tag=atomicindus08-20

 

[dr_clyde]

Hard turning is best done at high RPM with carbide tools, very light cuts. You don’t need coolant.

 

[dr_clyde]

Agree on the taking the interrupted cut in one pass if you can. Cutting hardened hex flats constantly hammering on your cutter can chip inserts pretty easily.

 

[The Cobbler]

I don't have inserts, they are brazed carbide tooling that my dad brought home from work many years ago . some real heavy stuff in there. Ill try a heavy cut , I think it might be capable .
what sort of luck will I have center drilling with the chisel end chucked in a 4 jaw chuck?

 

[zkling]

I think this is one of those...if you have to ask.

 

[Monza Harry]

As the cutting edge is 52 Rc or better that means that it is likely a high carbon possibly alloy steel and can work harden I am not real familiar with the manufacture of these specifically [could be the end only was carburized and induction hardened, or the whole thing is an alloy tool steel and the hammer end was annealed I am just not sure which way was used] so nice even cuts and a "little" compressed air for coolant with the carbide to resist heating as much as that will, just DON'T quench when finished let it cool until you can handle it. Carbide doesn't like to take light cuts you shouldn't really go under 1/2 the radius of the cutter if at all possible. Harry

 

[The Cobbler]

Thanks fro all the info.Sounds like It will either work , or it will be disaster

 

[Monza Harry]

Like the "Doc" says it will cut with the right tooling/approach. Post up results good or bad we all learn that way. Harry

 

[The Cobbler]

I plan to take some pre/during/post/ in use photos.
Thanks for the tips.

 

[zkling]

Why not just buy a pre made air hammer bit?

 

[The Cobbler]

^^^ That woudln't be any fun.
I need it this week, can't find anything that is available quickly without huge $$$ .
Besides, this is GJ, nothing has to make sense ! LOL

 

[rlitman]

I could. I want reasonable precision. want to make a chisel for my air hammer .
I could mount it in the lathe & grind it for sure. even by hand would probably get close enough . good idea. tks

Ok, that’s useful to know, and yeah grinding’s out then.

If it were me, I’d chop off the shank, and weld the head to a different chisel shank. But it’ll make an awful tool. Air hammer chisels rotate freely, which makes using wide ones like this not so nice.

Real pneumatic scrapers use a rotation stop mechanism. Either a hex shank, oval lock, or ball in groove retainer.

 

[The Cobbler]

OK, Old age brain fart. I am losing it ! LOL
I am pretty sure I have a 3" chisel with my SDS hammer drill set. totally forgot about that!

 

[rlitman]

OK, Old age brain fart. I am losing it ! LOL
I am pretty sure I have a 3" chisel with my SDS hammer drill set. totally forgot about that!

There ya go. Much better choice.

 

[gearhead1]

Yes material that hard can be machined. I’m not a career machinist, but I’ve done it. We had about 20 machinists where I used to work and would ask them machining questions all the time. They would machine A2 tool steel (57-62 HRC) with ceramic inserts.

 

[Everett33]

With the right tooling you can even machine (yes machine, not grind) solid carbide.

https://www.instagram.com/p/B-aIycsp44o/

 

[Kevin54]

Don't use a pointed tool because the interrupted cuts will destroy it. Use a rounded off carbide tool. As far as drilling, you will need a carbide center drill because the head will be hard also. And when cutting it, make sure you have a sleeve on your left arm because those chips jump off red hot.

 

[dutchgray]

Only the working end of a masons chisel will be really hard, the rest is fairly soft as far as any decent tool steel can be soft, so its shouldn't be to hard to machine them.
I have even cut them with the power hacksaw but the blades don't last long doing it, much better using an abrasive disc.
I have found any machine chisel, SDS, 19mm hex shank etc will be harder than a hand chisel at the striking end as they need to not deform with use.