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Forging S-7 Hand Tools


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Hi,
I am new here and glad to be part of the forum. I am about to embark on forging my own hand tools. Fullers, punches, chisels, etc. I have enough 3/4" S-7 kicking around for around 15 tools. Is there anything imparticular I need to take into consideration when working with S-7?
Thanks much.

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Don't quench them. Watch your temperature. There is a more narrow working range working S-7 then some of the simpler steels. I myself when first making hand tools started with coil springs, then went to known 5160, then S-7. Coil springs for myself when beginning was a cheap way to have plenty of steel to learn what I liked best doing my own tools. It also gave me room to explore and room for error, as I was not out much other then time. And time is simply put experience so good or bad it was good as long as I learned. You get S-7 too hot and it will cottage cheese itself all over when you hit it. Too cold and you are hitting a hardened steel. I take it you are already familiar with making hand tools? If not it might be easier on you to learn with a different steel. But it's all good, do what you will. It does make nice tools.

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The following material is from an older catalog, so should be double-checked. The incandescent colors I have added from "Metals for Engineering Craftsmen", RIB, London, England, 1964.

 

Forging S7 1950-2050F (bright orange-yellow). Do not forge below1700F(bright red). It can't be normalized, as it is air hardening. Anneal S7 1500-1550F (bright cherry red) losing 25 degrees per hour down to 1000F (faint red); then air cool.* Harden S7 1700-1750F (bright red) Cool in still air while placed on an inert material like a fire brick or pile of coke. Temper S7 from 400F to1150F (dark red). The Rockwell C range is 57-45. The higher temperatures are for hot work tools.

 

*A note about annealing. In my small shop situation, I don't have the heat treatment equipment to lose 25 degrees an hour. What I've done in the past is to take the annealing heat and bury the piece in dry lime until it is at ambient temperature.

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FWIW my blacksmith sensei used to anneal by soaking for about 45 minutes, then putting the stock into a vermiculite  tub and letting it cool before doing any necessary grinding. To  complete the tool, a soak at the orange temp for an appropriate time and an air quench followed by appropriate oven temper worked our well,….. your mileage may vary.

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I keep a bunch of 3/4" s-7 blanks next to the forge just that purpose. forge in the bright orange to yellow range and cool in vermiculite. it is one of my metals that I use the most. I like it for cutting tools. I use H-13 for drifts and hot punches. I am not a big fan of old coil springs by the time you cut heat and straighten them out. you could have made 2 to 3 punches.

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