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Just completed quick-change die system

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I've been working hard this past week building a quick-change die-holding setup for my new home-brewed Appalachian style hammer. It has been briefly tested as of tonight, and seems to be highly satisfactory. :)


I've never seen anyone else running this setup, but I'm sure it's already been done. Most hammers either have a dovetail system or use bolt-on dies. Since this is a home-brewed hammer and I want to be able to make my own dies since I am mucho el broke-o, and since I have no machining training, dovetails were right out for me. When it was time to build the hammer, I had this system and bolt-on dies as possibilities, and we went with the bolt-on dies initially. A lot of these Rusty-style hammers are built lighter, and it's easier to hang the base plates of the dies off the edge of the ram and anvil, making drilling mounting holes fairly simple. We drilled and tapped the holes directly into the ram and anvil of this hammer, and it turned out that none of the holes were square to each other.

I built my first set of dies that let me test the hammer and see what changes needed to be made, then tried to make a template that would let me drill the appropriate hole patterns. The template matched the holes in the test die's base plate, which would bolt to the anvil, but did not match the holes in the anvil. I found this most confusing and off-putting and realized just how much time I would spend in frustration trying to get bolt holes to match every time I made a new set of dies if I continued this route. So I changed course and went with my other idea, this quick-change system.

I've spent the last couple of days (among other things) building a set of combination dies out of railroad track that would a.) serve me well for many years, b.) allow me to test my new die-holding system before welding base plates onto my espensive 4140 fancy shmancy flat dies that will be my main dies and tooling platform, and c.) do a paying gig that needs done in time to ship for Christmas. A student of mine was finishing up a project tonight and had time while it was tempering in the toaster oven, so we decided to test the new dies/die-holding setup and make her a pair of tongs. The dies have not yet had their final trueing up and the sharp edges rounded, and I don't yet have much time working with the hammer and am still getting a feel for the level of control, so the tong halves came out rough but will be serviceable.

A view from the back side of the die. The narrow section was freehand cut with an oxyacetylene torch, then given a quick cleanup with an angle grinder. Final trueing and edge rounding still to come.


A view from the front, showing how the system actually works. The die is welded to a base plate of a standard dimension. In this case, I came across a whole bunch of cutoff drops at Ashley Salvage here in San Antonio that were 6" x 8" x 3/8". Since my ram is 6" x 5" at the bottom, this was perfect. I bought more than I thought I would ever need just to be sure I don't run out. The "keeper" slides that actually hold the dies in place are machined from 1" square cold rolled steel. This took some doing, as I have had no training in machining, and didn't have an adequate milling vise. I actually had to work on other things for a couple of days while I waited on one I bought from eBay was delivered because I had no other way of precisely holding the bar like I needed. The die base plate slides under the keepers and butts up against the stop at the back, once again made from 1" square. Then the swing arm is shut, the bolt tightened down, and the whole thing fits nice and snug and didn't move during the test run. This picture is with the die pulled partway out of the keepers.


In spite of the blurry picture, you can see three dots on the inside of the swingarm. These are little dollops of weld bead. If the base plate is a bit too short or uneven, these dots contacting the edge will help even everything out and make sure that the die stays snugly in place while being wailed on.


The fit is a bit too snug. When welding on the baseplate, it invariable warps upwards. However, these dies were plug welded as well as welded along the sides, and this kept it from warping as much as they might have otherwise. I thinned down the edges quickly and dirtily with an angle grinder to get them to fit in for tonight's test run, but a quick pass or two on the milling machine in the fulure will take care of things.

How well did this work? Being able to quickly change the dies is only a secondary consideration with this. However, it is an important one. I was able to take the top die out and turn it 180 degrees between heats so I could forge the offsets in the tong halves. The dies didn't even think about moving. I'm able to put the dies in either direction and top or bottom, somehting I would not have been able to do with the out-of-square bolt-down system. It is a bit bulky, but taken altogether, not so much as a dovetail sow block. I added 8 pounds 4 ounces to the ram, not including the weld beads, so I essentially have an 88 pound ram now.

Like I said, I don't recall ever seeing anyone use a similar system. I think I figured this one out pretty much myself, and I'm kind of stupidly pleased that I was able to do so, to borrow a phrase from another smith. Hopefully this will help someone out.

Oh, and the tong halves:



I'm kind of embarassed to admit that this is only my second pair of tongs I've worked on. Given that, the fact that the hammer tooling was not completely optimized, and that I was still getting used to the feel of the hammer's control, I think they're ok. There is still more work to be done before they're finished, including finishing drawing the reins out and roudnding the sharp corners, but we ran out of propane it it was the end of class time anyways. We'll pick it up again next year and finish them out.

Now to make more dies and auxiliary tooling. :)

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