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Questions about hammer dies


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I went to a tool making for power hammers seminar a few weeks ago. All the demo hammers had flat dies and all the material movement was done with the flat dies or with hand held tooling. I've been in the market for new dies for my LG but haven't gotten of my lazy ars to do anything about it yet. I used to think combo dies were the ticket but now I'm not so sure. If you were to buy one set of dies, What would you get and why?

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There is no universal answer....
I run 3 hammers two with flat dies and one with combi dies, I do 80%+ of my work on the comby dies . the other two hammers are for big stomping and hand tool work .
Most of my work is damascus and decorative tapers in varying section though , so I guess it depends on what you do .

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I alternate between two pairs. I have drawing ties that are slightly crowned and large flat dies these are twice as wide as my drawing dies. I use these two pairs about 90% of the time. If I had to chose one pair it would be the flat dies. I am not a big fan of combo dies they keep you away from the middle of the die (the best place to work) In mine and many other smiths opinion. I do change dies a lot. I wish I had a turret die changer B).

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Another vote for flat dies with a heavy radius on the edges. You can draw quite effectively with the edges and you can use tooling if you need it. It's hard to use tooling efficiently and safely with drawing dies.

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All,

I just bought a 25# LG with flat dies. The dies have a very square edge. The person I bought the hammer from bought them new and didn't use them. He mentioned that the dies need some work to get them correct. What radius is considered "heavy"


Thanks for this useful thread and the info in it

Brian Pierson

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I too would take flat dies over any other type for general forge work. Here's why:

1. They give you the most flexibility in terms of auxillary tooling, which you learned in the class you attended.
2. With a flat die you should be able to work either parrallel to or transverse to the long axis of the die. This feature is good when you want to get a very wide die bite or angled die bite for spreading rather than drawing.
3. As has already been noted, combo dies usually have the transition in the middle of the die and therefore you can't use the center of the die.
4. On hammers without subtantial guides, the off center loading is hard on the rest of the hammer.

If you are planning to do only a narrow range of work which consists primarily of drawing out, then combo dies could be a good choice for you. However, flat dies will draw very quickly once you learn how to use them effectively. My work consists primarily of forging 2x2x6 inch blocks of mokume to other sizes specified by my customer and I do all the work on flat dies. I have made large dies with multiple slots and grooves to allow me to forge the width and thickness in the same set up without having to use hand held stop blocks. Dimensional control is critical in this work since the cost of material is high. With this setup I can typically hold to +0.010" on thickness and a bit more than that on the width. Undertanding how metal moves and how to contol that movement allows you to use the tools best suited to the job you want to accomplish. This takes practice, but is also faciliated by studying with other smiths, especially those who have an industrial background. In another thread someone was mentioning the work done at Scot Forge. I am one of the metallurgists at Scot and I can tell you that ALL our presses and hammers are set up with flat dies which we use for both drawing and spreading, upsetting, punching etc. The only other shape of die we use is a V die for working hollows. Everything else can be done on flat dies.

To answer the question regarding die radius and how much should be on the die: That depends on the size of the hammer. I would suggest that the radius should be (at a minimum) large enough so that the penetration of a single blow into the typical work piece will not leave any vertical surface that could lap when then next blow is applied on top of that. The radii on my dies are all just hand ground by eye but if I had to guess I'd say they are about 3/16-1/4".

Patrick

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Wow! Thanks for all the great input. I am no longer on the fence, Flat dies it is :D

Patrick-
Care to show pictures of the mokume? Good point on the radius size too.

Fosterob-
Just auditing the class, I learned a ton. I didn't hear that from Toby... It would seem you would want the mating edges of the top and bottom dies to have the same radius, Or did I miss understand you? Hows that new hammer coming?

Reasons for flat dies-
Being able to use the center mass of the die, very important on the wimpy guided LG (Thanks Grant and southshore) it is also the sweet spot.
Watching Toby make a taper with his hit turn system. He is able to take the taper on a 1-1/2" square to a point of 1/8" or less in 5" of length, clean up with a round back flatter. In one heat!!!
Making spring tooling that indexes of the dies would not work so well with comb dies or drawing dies.
Changing dies is a P.I.N.A!

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Fe,
Yes top and bottom the same. I have one hammer (the new one) that the dies are ground to radius on the front and back (long)edges but not on the sides(short), they are more square. It came that way and I have not had time to form an opinion on that yet.
New hammer is here in its temporary home, I need to hook up the motor starter and phase converter to be able to run it. Without being on its foundation I am hesitant to run it hard. I need to plan its permanent location and dig the hole to put the foundation back in the ground.
Rob

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Changing dies is a P.I.N.A!


Changing dies in a hammer with dovetails should not be that hard. Make sure your keys fit extremely well and then grease, oil or anti seize your key and it should go in and out fairly easily and yet not loosen. That way you can put in other dies fairly quickly.
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There are quick change alternatives. I didn't like the bulky bolt on box system so I designed and fabricated the quick change die system shown below.

The beauty of the system is that you can change the dies rapidly. In addition to flat and drawing dies, I have fabricated a number of fuller dies ( not shown). Although my Hammer is relatively small ( Tup 53 pounds) the system may be ( ? ) scaleable upwards for larger hammers. The die inserts are so easily fabricated that experimentation is practical for small projects.

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post-14777-0-86759200-1296870896_thumb.j

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interesting setup dan- How are you attaching the pins?



The pins are secured by the socket head machine screws at each end of the die holder body. I have never had a problem with them coming loose.

The die holder bodies are modified commercial flat dies.


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I think Fe-Wood wants to know how they are attached to the removable top piece.
Rob



I use a hole locator jig to drill holes into the bottom of the die or as sometimes applies the die mounting plate. Each of the two holes are countersunk to provide relief around the die pins. The holes are sized for die pins to provide a drive fit. After the pins driven home they are welded, using the countersink as relief for a secure weld. The welds are ground flush with the die bottom.



The socket head screws, at each end of the die holder body, tighten against the die pins after they are inserted into the die holder body.


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Rob got it- I was thinking maybe you threaded them in or even a press fit. Surely something to think about. Thanks for sharing. I like it!!! Is the dovetailed part of the die 4140 or the same material as the "face"? How long have you used this system? no problem with cupping?

Clinton- combo dies are great! Using top tools with combo's is a little more of a challenge because you can't really use the center mass of the hammer.... If you know what I mean....

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Changing dies in a hammer with dovetails should not be that hard. Make sure your keys fit extremely well and then grease, oil or anti seize your key and it should go in and out fairly easily and yet not loosen. That way you can put in other dies fairly quickly.

Changing the dies is just time consuming and I don't like pounding on the blocks that much. My Die block has been repaired once so I'm a bit timid about wailing on it often to set the wedge each time I would do a Die change.
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these are dovetail adaptors? I got from Sid at Little Giant. The dovetail stays in the hammer and your dies bolt to them with 2 bolts. shown are flat dies in the hammer and drawing dies. I make dies out of A36. these are 2"x3".

post-91-0-94671300-1296913924_thumb.jpg

post-91-0-19338800-1296914274_thumb.jpg

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FE, I bought the hammer around 1994-95 and bought a new set of flat dies while at the next ABANA conference . I fabricated the drawing and flat dies immediately and started using them. It is not like I am banging away 8 hours a day every day but it has been a long time since I started using them with no failures. The bottom holder die should last a lifetime. The inserts are so easily made that the benefit of quick change should over ride any concern about wear. However my original drawing and flat dies are still is service. The drawing die is the one pictured.

The system that Bob S has posted does the same thing that my system does. For my fuller dies I use a base plate like Bob's and weld on what ever fuller shape I want. The bottom plates are easily fabricated I use a steel jig to accurately drill the holes. With Bob's system the holder dies would need to be longer to maintain die size.

The bottom holder die is easily fabricated from a standard commercial flat die using only a drill press. Believe it or not I once machined the dovetails into a couple of blocks of steel, on my radial arm saw, to make dies for an old 25 pound Moluch that I had. I cut those blocks out of an old shear blade ( a giant one, but that is another story). My flat and drawing dies for this system are made from that steel and heat treated in my shop.

No one system serves all needs . However for smiths, like us , working alone, who have one power hammer, and do a variety of projects using moderately sized stock, a system like this makes sense.

I could see how the pins might be threaded into the die block. Any thing that works - don't knock it. Just happens that I did mine another way.







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If you plan on using tooling yes flat dies are the best choice, I have used top tools with my combo dies the radius on my dies is rather flat on top so I am able to use the center of the dies with good results. I will be making more dies soon, I plan on flat dies and drawing dies.

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I could see how the pins might be threaded into the die block. Any thing that works - don't knock it. Just happens that I did mine another way.


Not knocking at all!!! I like it! I have a LG with REALLY worn dies. So worn, I have a 1/2" shim under the bottom die. I could mill these flat and use your system. Coming up with smaller die materials is always easier....

I think I like this system better than the one Sid uses because the likely hood of the bolts backing out seems less to me.
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