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I Forge Iron

Hot Chisels & Punches


Ron Hicks

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Ron: Coil springs are usually the easiest to get and the most convenient shape. The newer the spring, the better. Once a spring has been cycled a few million times, it can develop some stress fractures that will show up after you heat-treat and start using the tool.

Most of the time, the coil springs can be simply hardened and tempered as water-hardening steel. They are fairly forgiving to work with, in other words.

They don't really take heat all THAT well. You have to keep them cool as you work by working a bit and quenching the tool as you go along. Not a big deal, and second nature after awhile.

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Ive made one from coil spring - guess Im letting it get to hot.
I have some 1 in. bar that at one time printed on them Tungsten Bar thought about using it?I also have some S7 5/8 bar .

Im slitting and drifting a 3/8 hole through 5/8 round bar, is this to small for a hot chisel?

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Ron: In order: Yes; Don't know; Yes; No. :)

If you watch an experienced blacksmith using tooling made from simple carbon steels, there is a near-dance that goes with working and quenching. You don't let the tool linger in the hot piece, but rather get on with it quickly and remove it frequently. For instance, if you punch a hole with a coil spring punch by hammering till it bottoms out on the anvil by feel, the punch could be at a soft red heat by that time and will mushroom in the bottom of the hole. Now it is stuck, and as you frantically try to get it out, the hot piece begins to cool making a nice shrink fit around your punch. By the time you surgically remove it, you will have to completely rework the punch before you can use it again. So punch quickly, cool quickly, and dip in some coal dust to make a lubricating barrier before putting it back in the hot work.

Don't know anything about your Tungsten Bar.

S-7 is great stuff for tooling. It is an air-hardening tool steel designed to take shock. All you have to do is forge it and let it cool in the air. There is more elaborate heat-treating if you want to, but that is sufficient for hand tools for blacksmiths.

A 3/8" hole is not too small for slitting and drifting. I prefer to slot punch rather than slit, but either one is routine.

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Ron Hicks,

H13 is used extensively in forge shops for high temperature tooling and retains hardness well even when heated to a dull red. Composition is 6% chrome and 1% moly. Tools made from H13 hold up even under fair severe abuse.

H23, H24, H25 contain 10 to 18% tungsten. If your bar is one of these alloys, then it will hold hardness up to a bright red heat. The down side comes if you try to forge any of these alloys. They require temperature control that far exceeds a simple hand forge. The tools I have made from H13 have all been machined to size, no forging.

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I use H13 exclusively for hot tools and never regretted it. Quite a few of my tools are machined from annealed stock but some were forged. I have one particular chisel that is about 2x2 inches wide at the cutting side (sort of paddle shaped below the struck shank) and about 3/32 thick at the top down to 1/32 or so at the edge. This will cut right thru 1" hot square stock without removing to cool and won't deform if I don't cut thru and hit the anvil. As Ed said, most plain steels would need removal for cooling and you'd risk embrittlement (and breakage on the next lick), while H13 will allow water cooling below about 1000 degrees without worrying if it will come to pieces when struck.

Junkyard steel sometimes makes good tools and sometimes not but your labor is worth more - so why not buy the best material and use it as intended?

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Ed
I made a punch,slitting chisel,& straight chisel from the S7. I tried them out & seem to work real good. I quenched in water every 2 licks.

Not sure If its the right thing to call it - Red Hard ?? any how this S7 you get it above a orange heat and hit it - it cracks. I got lucky and was able to cut off the cracked part. I forged it at orange and it was OK.
Maybe its called Red Short ?

Ron

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Ron: I don't know what you call it... maybe DOGGONIT :)

But, yes, S-7 falls apart at too high a heat, and is very difficult to forge below orange. That doesn't leave much room. If you look here:

Diehl Steel - S-7 Air Hardening tool Steel

you can see that the recommended forging temperature range is only 150 degrees. In other words, it's probably better if you are starting with a piece fairly close to the dimensions you want or you will wear yourself out.

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My "blacksmith's heat treat" for H13 is to either: Machine from annealed bar stock then heat to bright orange and let air cool - or - forge to shape and let air cool. Both of these have worked well enough that nothing has broken on me in use. S7 is quite good but has a tendency to heat check and/or crack from improper heat treat.

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The S7 forged good at an orange heat , kinda slow not much time.I planned on making knives from it when I bought it years ago.I will make more chisels & punches from it.

HWooldridge
I havent tried the 1 in. rd bar (tungsten bar) .
Long while back I forged a little of it, Im pretty sure its air hardening .
Ill watch my heat really close, I bet it will make very good tools
Ron

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Ron
All my HOT punchin ,cutting and fullering tools are made from;
h13
s1
M4
the most I use h13 all the above steels are air quench u forge the tool and let it cool . some times i cool them in the gas forge and let it cool slow.
and some times when i need them harder i cool them under a ventilator.
it will make them harder but mor brittle u have to be mor carfull when use.
you can use coil spring ,rear exle , 4340, they are not good enough
because u''ll have to cool them often .
if u can get the exhaust motor ventils they are very good fore driffts
hofi

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Thanks Guys
Ive made a few for hot work
1 slitter 3/8, 3 round punches 3/16-1/4-3/8,flat chisels 5/8-1 1/4, & 1 butcher 1 1/4.

I tried some scrap from the Road Grader Blade and made a Square Center Punch ,hardened and tempered. Seems like it works really good,I drove it through cold 3/16 mild steel.Im goning to try a Cold Chisel form the Grader Blade also.

I made most of the punches and chisels to use on the Treadle Hammer, not really sure what I need.
Any Ideas
Ron

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