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Hammer eye punch n drift set

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Over the last few days in the workshop I hand forged down some reclaimed jackhammer bits into a hand punch and drift set for making hammer eyes and top tool eyes. 


I know there is some debate as to the necessity to heat treat this type of tooling but I would be curious to hear some thoughts on the matter.

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Being forged I highly recommend you draw a temper on the struck end past blue and keep it dressed. The snap sound you hear when a piece of hardened steel chips isn't really the sound of the steel breaking, it's the chip breaking the sound barrier. Sure it doesn't go that fast very far, a few feet usually but your hide is within range of that jagged bullet. 


Frosty The Lucky.

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Frosty, I understand that the struck end should not be hardened. I definitely don't want any chips flying my way. 

Just to clarify for discussions sake, these tools have not been hardened in a quench. They were hand forged then allowed to cool slowly in the embers and ash of my charcoal forge for about 15 or 20 minutes then on the fire brick that tops my forge for another while maybe 30 or 40 minutes, then open air on a brick away from the forge until cool to touch. So no hardening from a quench. 

Are you still suggesting a temper draw on the struck end? Even if the tool has not been quenched off? I  want to make sure I'm being safe.


I am also curious about the necessity, or not to harden and temper the working end of the tooling. The case being that the tooling in contact with the billet is going to draw a temper and diminish any hardening and tempering I had done previously to the tools. Or am I misunderstanding this through my lack of experience? 

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Thomas, unfortunately I have no data on the steel I started with. Being that my search for info on the manufacturer of the bits came up with nothing that would indicate the type of steel used, and produced no data sheets to consult. I can't even begin guess what they were made from. Other than what people half a world away make as guesses based on their experience and knowledge. 

Understanding that I'm starting from a point of disadvantage, due lack of information, starting with unknown steel. I know that there is a risk of deformation or failure of the tools from usage. Would it be too irresponsible of me to use the tooling as is, not heat treated? Accepting the fact that I will have to re dress them regularly, if not even reforge or scrap due to some unforseen failures.  

I have heard of smiths making drifts from mild steel, with the thought that it is used more like a disposable tool, knowing that it will likely deform after a few uses.  And my understanding is that, a high carbon steel not heat treated, would still be tougher and hold up longer than a mild steel tool of the same usage....? 

I have also encountered lots of people around the internet saying that S7 is a common steel used for jackhammer bits.

Both 1050 and S7 have roughly similar carbon content and even similar applications, but a few of the other chemicals that make up the steel are very different,  and obviously they have very different metallurgical properties and react differently when it comes to the heat treating, hardening, tempering and annealing processes. 

Is there any testing I can do in the workshop to determine if it is more likely to be one or the other without expensive high tech gadgets. 

Would a spark test be able to highlight differences in chemical composition other than carbon content, if I knew what I was looking for?

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Spark test would definitely show a difference.  As would how it works under the hammer---S series steel would laugh at you hammering on it.  May I commend to your attention Grant Sarver's old post here on IFI: (Browser search  jackhammer bit site:iforgeiron.com   )

"Having been a manufacturer of paving breaker steel for many years, over time, I had spectrographs done on every other manufacturers steel. To the best of my knowledge, the only time an "S" series steel has been used is for specific applications and usually that was only .680 chipper steel. These are a commodity product and the finished tool sells for less than the cost of "S" series steel.

For most of the last century 1078 was manufactured specifically for this purpose. Essentially a high silicone 1080. Brunner & Lay (the largest bit manufacturer in the world) uses a modified 1045. Vulcan used 1078 for most of a century and more recently switched to 15B40, a boron steel much like 4340. This steel will spectrograph as 1040/1045 because the boron is minute and often overlooked. I made millions of bits from 8630 and 8640 steel. Many chipper steels are made from 9260, an AISI grade very close to S-5 in chemistry.

Junkyard rules apply."


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Ok cool, thanks for all the info Thomas. Im pretty sure one of them was Brunner & Lay. I forget what the other was. But ill look again. Next time I am at the workshop. That should get me closer to a much more well educated guess at what these scraps are. 

You rock Thomas!

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One of my BS's is geology!

There is a common misconception that jackhammer bits are S series due to them being listed as that in a popular junkyard steel table. I think that is due to that alloy being mentioned in Machinerys Handbook as being good for that purpose; and they are!  Just WAY more expensive than the simpler alloys that do "ok".  Titanium would make a great car body---you seen any of them on the road?  My father used to say that every engineering equation has to have a $ in it somewhere...

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