jack hammer bits

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Posted · Report post

I have heard of people using jack hammer bits for all sorts of tool projects, and I just recently acquired many from a silent auction. I know that tools are tempered for different applications and if something is tempered for use as a jack hammer bit, would it be too hard to use as a cold chisel? As far as forging goes, are there any tricks to forging and tempering them?

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Posted · Report post

ive used a jackhammer bit for cut off heartys in the past and they worked good i didnt try to harden or temper i left um to air harden . the problem is figureing out what steel they are .. i liked um cause they already had a snoulder in um i just forged um to fit my hearty hole then forged um to shape .. they were kinda tough but worked well.. good luck

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Posted · Report post

I have heard that they are a tough steel to hand hammer, but are an excellent material for tooling. I agree to just let it air harden and see how it works out.

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Posted · Report post

IIRC, they are S-7. Good for striking tools.

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Posted · Report post

Jack hammer bits are fantasic! I have made cut off hardies from them, and as previously mentioned, I let them air cool.

Also, last summer I made a geologist hammer from a jack hammer bit. I quenched that one in warm oil. I used it last summer hunting for fossils. There isn't a rock that can stand up to this hammer!! I don't have a power hammer yet and jack hammer bits are a little tough to forge. My son helped me with a sledge.

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Posted · Report post

As previously mentioned they are tough stuff... a power hammer is the best "trick" for forging them. They make tough tools though and I like them a lot. Chisels, punches, drifts, hardies, and small hammers are good things to make of them.

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Posted · Report post

I've used bits from Brunner and Lay, my understanding is the heavy ones are made from 1045 M.
I quench in brine, and temper to a dark straw with very good results when making heavy masons chisels.

It is also my understanding that S7 is NOT typically used. I think that common misconception comes from tool steel selector guides stating "S" series steel would work well for paving breakers, etc. This info comes from Grant Sarver and B&L.

If you can find the brand on your bits you may be able to find what alloy they are made from and proceed with more confidence in your heat treat or just heat to about 1500/1600
quench in whatever is handy and temper somewhere between straw and purple.

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Posted (edited) · Report post

Having been a manufacturer of paving breaker bits, I can tell you that no one uses S-7 or any real tool steel ( at least not in 1", 1-1/8, 1-1/4). I've had just about every one spectrographed. B&L is a modified 1045, Vulcan used to use 1078 but now uses 15B30, Pioneer/DelSteel is 1078 or 9260 for their "alloy" bits. Apex (my old brand) are 8630. These things sell new (at full discount) for about what tool steel costs per pound. Everybody is looking for the cheapest thing that will do the job. People expect these bits to be really great stuff, perception trumps reality every time.

BTW: "Paving breaker" bits are solid, "jackhammer" bits have a hole down the center.

Edited by nakedanvil

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Posted · Report post

Having been a manufacturer of paving breaker bits, I can tell you that no one uses S-7 or any real tool steel ( at least not in 1", 1-1/8, 1-1/4). I've had just about every one spectrographed. B&L is a modified 1045, Vulcan used to use 1078 but now uses 15B30, Pioneer/DelSteel is 1078 or 9260 for their "alloy" bits. Apex (my old brand) are 8630. These things sell new (at full discount) for about what tool steel costs per pound. Everybody is looking for the cheapest thing that will do the job. People expect these bits to be really great stuff, perception trumps reality every time.

BTW: "Paving breaker" bits are solid, "jackhammer" bits have a hole down the center.


Thanks Grant, I have always been told they are S-7....even here on IFI, a few years back, it was said they are S-7. Good to know different. Still a good steel for the 'cheap smith' right?

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Posted · Report post

Well, like Andrew mentioned, some of the tool steel manufacturers like to recommend that and S series is used in "some" chipper steels, the stuff that's 3/4 - 7/8 round with an oval or round collar. But much of that is 9260 which is an AISI grade very close to S-7.

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Posted · Report post

B&L is a modified 1045, People expect these bits to be really great stuff, perception trumps reality every time.



Reality is (from my limited experience) that 1045 is 'really great stuff'. For most shop tooling, hammers, swages etc 1045 is great and pretty cheap. 'Jackhammer' bits are a gold mine of steel for cheap, sometimes free or next to it. The built in collar is a bonus.

Bob

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Posted · Report post

I once made a slitting punch out of a paving breaker bit. The smith who gave me the broken bit told me it was pretty tough stuff, and red hard as well. It sparked as 1050, not as S-7, and I can tell the difference. I took it to a hammer-in, and said that it was a jack hammer bit. One of the guys said that this meant that it was S-5, and pretty tough stuff. He proceeded to go to town on it and ended up getting it stuck in a hammer head. The tip, when red, flared out, and locked in. By the time we got it unstuck, it was ruined. The fellow said, "I thought you told me that this punch was red hard." No, I said, I only told him that it was a jack hammer bit. Then I pulled out a real S-7 slitter. This one I had spark tested, and it really was S-7. He proceed to do exactly the same thing (sledge hard more than 4 times without cooling), and the tool went all the way through. It was red when it poked through the other end. "This," he said, "is red hard." Real S-7 was a lot harder to forge than that jack hammer bit. I guess that three tests were enough for this piece. Spark test, forge test, and use test all said that the jack hammer bit was simple carbon steel. Oh yeah, Grant says so too. :)

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Posted · Report post

Well, regardless, it's good enough for some applications. The geologist hammer I made stands up well and I paid .50 cents for the jack hammer bit. The cut off hardy I made from another jack hammer bit has been holding up for over 5 years now without any problems.

I guess it comes down to application. I wouldn't use a jack hammer bit to make a punch or slitter anyway, too much work to draw it down to size since I don't have a power hammer. It's easer to purchase S-7, and you know what your getting!

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Posted · Report post

What this really highlights is that, for many things, you don't really need exotic steels. Our forefathers (for a couple thousand years) got by just fine with "tool steels" that were hardly better than 1045.

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