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  • Forging/heat treating a hammer

    I'm into week 5 of the Austin Community College power hammer class, and last week we forged blacksmith hammers. Thought some of you might be interested...

    This is what we were shooting for: one of Will's finished hammers:



    We started off with 2" rounds of 1045 (excellent toughness). Blacksmiths tend to like a hammer around a kilogram (2.2 lbs). So you figure out how heavy a hammer you want, and calculate the weight of the round bar with a materials calculator, and add 5 - 10% for oxidation loss from the fire scale.

    The forge is definitely not conducive to taking pictures -- it's hot, there are 4 power hammers running with various dies and fixtures, and 6 students running around with hot forgings.

    After you squared-up the round bar into the rough hammer shape and broken the edges comes the fun part: drifting the eye hole. You start by carefully marking-out the drift slot on the centerline, with what will be the hammer face 1/8" forward of what will be the peen. If you're off at all on the layout, the hammer face won't be centered on the shaft. It happens.

    Then you get the hammer blank hot, and slit a hole through the block on the power hammer. It's a lot of work, and you need to slit from both sides to keep the hole centered.

    The whole time you're doing this, the block is @ 1800 - 2,000°F, and if you don't hit it true, you turn your hammer head into a rhombus, which is a PITA to fix:



    Will with a hammer he just slit. He's holding the big drift that we're about to pound into the hammers with 12 lb sledges. Notice the black section through the middle of the hammer head: that's where the metal cool from the slitting chisel driving through the forging:



    This is one of the six hammer blanks slitted. I don't know who's it was, but notice the slit isn't straight -- oops!

    Last edited by lazlo; 07-02-2011, 12:45 PM.
    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

  • #2
    Now for the the Old World blacksmithing: each person re-heats their hammer blank, picks a drift (you want to use the same drift each time), and puts the hot hammer blank on a drifting stand. The owner of the blank holds the drift, and 3 others strike with sledges, driving the drift into the hammer body. This is exactly like the black and white videos of the blacksmiths forging ship's anchors and chains.

    People have asked if you can forge tool steel. High carbon steel is a lot stiffer under the hammer than mild steel. I've been forging tool steel blanks for katanas, and 52100, W2 et al is much stiffer than high carbon steel...



    It gets pretty crazy with three people striking and a fourth person holding the stake, but after 5 weeks you get into a rhythm...

    Each time, you get the drift a little further into the hot hammer, then you run over to the power hammer and holding the hammer with the eye drift, you start forming the cheeks:



    After each trip to the drifting stand, it's back into the fire. Rinse, repeat. Many times...



    By the time you've gotten the eye drift through on both sides, and shaped the cheeks on each heat, your blank looks something like this. I've fullered the hammer head at this point. That's partly decorative, but it also isolates the mass of the hammer face from the body, so it's easier to shape:

    Last edited by lazlo; 07-02-2011, 12:49 PM.
    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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    • #3
      The next step is to forge the peen, which was the most difficult part, in my experience. Will's hammers have a beautiful fishtail peen -- it flares-out on the sides. That's not only decorative, but you dress the points of the fishtail so you have a rounding face when you hold the peen diagonally.

      To get the fishtail, you need to use flat dies on the power hammer, and step down from the body to the tip of the peen. If you use accidentally use drawing dies (curved dies) like I did here, you'll pull out a straight tapered peen with no fishtail flare



      So I got to class early on Wednesday, and upset the peen. That involved getting the peen hot (and not the body), clamping the glowing hammer head in a leg vise, peen up, and hammering the thin edge of the peen to mushroom it. That flares it in both directions (makes the peen fat), so another trip to the power hammer with flat dies this time, and I ended up with this:



      At that point, you heat the head up one final time, drive the eye drift on softly (just as a handle), and dress the hammer face and peen.

      For a blacksmith hammer, you want a large radius curve on the face. The peen is radiused in two axis': long-wise and front to back. If you forge these shapes, you don't have to grind off material from the hammer, which throws off your weight calculation.

      This is after dressing and some cleanup on the belt grinder:

      "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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      • #4
        Finally, the fun part -- differentially heat treating the hammer. This is a blacksmith shop, so the heat treat is amazingly simple and effective: you gradually heat the hammer to non-magnetic. That means putting the hammer on the hearth of the forge, then slowly moving it into the forge over a period of about 10 minutes. You want to reach austentizing temperature (around 1500°F), but you don't want to ruin the grain size by overheating it. The forge is 2,000° F, so you have to carefully watch it, and keep pulling the hammer out and checking against a magnet. When it hits the Curie point (non-magnetic), you quench it into a bucket of water at 115°F.

        At that point, the hammer is glass hard. If you drop it onto the concrete floor, it will likely shatter. Checking the hammer face with a fresh file, it just skidded across. One of the students described it as "hard ice."

        This is what I thought was the really neat part: differentially tempering the hammer. You take the hammer to the belt grinder, and grind/polish clean faces on the face, peen, and the cheek bevels. Then you take an acetylene torch, and carefully heat the center of the hammer. This "fire cleans" the hammer: the high temperature of the torch flame blows the scale off, and slowly builds-up the temperature of the body. The body turns purple, and soon afterward the face and peen turn a very light silver-straw color. At that point, you quench the hammer again (since the core of the hammer is still hot), and if you did everything right, you end up with a hammer face and peen around 50 HRc, and a main body around mid 40's for maximum toughness.

        Here's the final product. The handle is Osage Orange -- very hard and dense, doesn't rot, and doesn't transmit shock up the handle like oak does. We're going to handle the hammer and stain on Wednesday -- the Osage Orange turns that beautiful redish-brown in the first picture. It's hard to see the violet color I left on the main body -- need to take another picture:

        Last edited by lazlo; 07-02-2011, 01:19 PM.
        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

        Comment


        • #5
          If you wanted a hammer why didn't you just go down to Harbor Freight?



          Nice job BTW, thanks for posting. Didn't you do some work on I Katana I'm very keen to see you post on that.

          Pete

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          • #6
            Thanks for the instructional tour. I've been a machinist a long time but I've never done any forging in my life. I found your pictures and text explanations fascinating. Very nice work too by the way !

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            • #7
              Very cool!!
              Thanks for that.

              rollin'

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              • #8
                Neat project Looks fun and challenging. Lots of good education as well. Nice job!

                Comment


                • #9
                  Looks good,Osage Orange handles,must be a Texas thing

                  You gonna leave the head rough,or polish it out all the way?
                  I just need one more tool,just one!

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                  • #10
                    After reading the text and looking at the pictures I have a new respect for hammers.
                    But now I can't use one of My favorite phrases any more
                    "That boy is dumber than a bag of hammers."

                    Nice work!

                    Steve

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                    • #11
                      Thanks for posting that great gallery of pictures, very educational!!

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                      • #12
                        I've enjoyed blacksmithing for over 50 years and have made many forging tools. For hammer blanks I go to stores like Goodwill and find old "made in the USA" sledge or ball peen hammers and reforge them into any shape I need. Cost is minimal! I see "tools" in all kinds of junk. Now you will too!

                        .
                        Last edited by Mike Burdick; 07-02-2011, 08:36 PM.

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                        • #13
                          Nice Robert, thanks for sharing it
                          .

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                          • #14
                            Originally posted by doctor demo
                            After reading the text and looking at the pictures I have a new respect for hammers.
                            But now I can't use one of My favorite phrases any more
                            "That boy is dumber than a bag of hammers."
                            Nice work!
                            Steve
                            Sure you can. Anyone who would put such artworks into a bag where they would smash and dent into eachother is pertty dumb.

                            Originally posted by lazlo
                            I don't know who's it was, but notice the slit isn't straight -- oops!
                            Just call it an ergonomic hammer, Nobody will question it.
                            Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                            • #15
                              May be a silly question here but somewhat on topic,, i've read Alex Wagers books a few times about smithing, if anyone hasn,t seen them, they're not a bad read at all, an interesting guy.

                              ( I posted this in response to the above post about "Seeing" tools in scrap, as Wagers often did,, and i suppose many who forge and work metal also do.)

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