Welded Power Hammer Dovetails

[PaulKrzysz]

I will begin making my Power Hammer soon.
 
I am designing everything right now. I am trying to avail using bolt on dies.
 
This is what I came up with.

Basically, a piece of (1.5''?) Hex Bar cut into quarters, and welded into a configuration which would make both male and female dovetails.
 
The Male end will be two pieces of the hex, with a plate on top, to the plate the 4140 for the dies steel will be welded.
1) Hex Bar
2) Cut in Half
3)Cut in Quarters
4)Weld to plate
5) Gussets welded to strengthen the dovetails
6)Drawing of Female Half
7)Drawing of Male End 
 
 
Please let me know what you guys think, and concerns, if it will at all work, ect.

[Nick]

Why are you cutting the piece of the hex  that will be welded to the die?  Just leave it in half and quarter the lower section.

[ThomasPowers]

how do you adjust them for wear?

[HWooldridge]

Why not just bolt on the dies and skip the intermediate dovetail?

[PaulKrzysz]

Why are you cutting the piece of the hex that will be welded to the die? Just leave it in half and quarter the lower section.

Cutting it at the right angle might prove to be a challenge.
I will be making the hammer at someone else's shop so I am not sure if i could cut it like that because it would have to be resting on the table on one of the 120 degree angles.

If I can do as you suggested I will, no point in wasting
 

how do you adjust them for wear?

I don't know Thomas, how do you adjust a one piece cast iron anvil/sow block on a early style little giant?
 

Why not just bolt on the dies and skip the intermediate dovetail?

Please correct me if I am mistaken.
I want to go with the dovetails because it is my understanding that it is easier to tap out/drive in 2 wedges, then it is to loosen/tighten 8 bolts (Or 4 if that is what you want to go with).

I hope the extra work in making the dies holders this way pays off.

[macbruce]

You don't need 8 bolts, two (per die) will do just fine if you nix the dovetail......never mind the tool holder in the foreground.

[Dodge]

 

 

"Please correct me if I am mistaken.
I want to go with the dovetails because it is my understanding that it is easier to tap out/drive in 2 wedges, then it is to loosen/tighten 8 bolts (Or 4 if that is what you want to go with)."
 

 

I'm just using two 1/2" socket head bolts on diagonal corners without issue. An air impact at the ready makes short work of die changes

 

[HWooldridge]

I believe the habit of dovetails (for dies) are primarily a carryover from the days of cast iron. Steel holds threads better than cast iron so a few bolts are all that's needed.

[Judson Yaggy]

I'd just bolt them on as well but if you do go down this road warpage of your base plate could be an issue.  For dovetails to work they have to mate very closely and as drawn the baseplate will warp it's edges up when welded, throwing the mating surfaces of your dovetails out of parallel.

[patrick]

If you want to use a dovetail dies system, which does work very well, I'd suggest using the two key per dies system like what Bradley and a few other hammer makers did. The advantage of this style is that dovetail in both the sow block and the die is a straight dovetail. On a single key per die system the dove tail also is tapered along its length. This means you have to machine a compound angle on either the sow block or the die. With the two key method, you can machine the dovetail with a dove tail cutter on a mill and the stock held paraellel to the mill table- a very easy set up. On my Bradley, the dovetail angle is  5 degrees so I had a local tool grinder make me a mill with a reverse taper to match. I have made dies with integral dovetails, which is my preferred method, but I made several sets where I machined the dove tail and welded it to the die block. Both methods work and if you don't have access to a mill, it should be fairly inexpesive to have a local machine shop make up a flat bar with the dove tails cut on the edge. You can then cut what ever length you need and weld to the die block you're making. I don't have much issue changing dies and I do it a lot. A few smacks with a sledge and everything loosens up.The keys in my hammer are tapered 1/8" per foot which is fairly common. Before I had my own mill, I actually forged several dovetailed blocks right in the sow block. A little clean up with a grinder and they were ready to be welded to my die blocks.

[PaulKrzysz]

If you want to use a dovetail dies system, which does work very well, I'd suggest using the two key per dies system like what Bradley and a few other hammer makers did. The advantage of this style is that dovetail in both the sow block and the die is a straight dovetail. On a single key per die system the dove tail also is tapered along its length. This means you have to machine a compound angle on either the sow block or the die. With the two key method, you can machine the dovetail with a dove tail cutter on a mill and the stock held paraellel to the mill table- a very easy set up. On my Bradley, the dovetail angle is  5 degrees so I had a local tool grinder make me a mill with a reverse taper to match. I have made dies with integral dovetails, which is my preferred method, but I made several sets where I machined the dove tail and welded it to the die block. Both methods work and if you don't have access to a mill, it should be fairly inexpesive to have a local machine shop make up a flat bar with the dove tails cut on the edge. You can then cut what ever length you need and weld to the die block you're making. I don't have much issue changing dies and I do it a lot. A few smacks with a sledge and everything loosens up.The keys in my hammer are tapered 1/8" per foot which is fairly common. Before I had my own mill, I actually forged several dovetailed blocks right in the sow block. A little clean up with a grinder and they were ready to be welded to my die blocks.

 

Patrick are you saying that if both the female and male dovetails where parallel, I could just lock them in using two wedges tapered wedges which lock against one another?
Seems like a clever option

[JNewman]

Bolt on dies work well and are likely the best way to go right now.  But dovetails are more reliable for keeping die alignment and are a more rugged method of retaining dies than bolt on.   I would forget the hex stock though.  Hammer dovetails are typically only 7 or 8 degrees as opposed to the 30 degrees you will get with your hex.  Cutting the hex accurately longitudinally will be difficult.   As well I think you will find it difficult to to maintain the dovetail angle while welding with such a small bearing surface  on the bottom. 

 

I made a set of weld on dovetail dies for a treadle hammer quite a few years ago, they worked very well.   I used 1"x2" flatbar for the dovetail with the dovetail angle ground on with a disc sander.   If I were to do it again today I would probably use 3/4" or 5/8" flat instead of the 1" as it would require less grinding.  I think I used 10 degrees for the dovetails the 7 or 8 commonly used would help reducing the grinding.  I think this would actually be less work than cutting the hex even if you had to use an angle grinder, files and a protractor or template.  If you do make dovetails make sure you grease your keys well every time you drive them in. Steel on steel is very prone to galling, as well without the grease rust will lock your keys into place so solidly you may not be able to remove them.

[JNewman]

Patrick's 5 degrees would require even less grinding than the 7 or 8.

 

I forgot to mention.  I drilled dowel holes in the flat bars and into the anvil that made up the female dovetail because the key puts an extreme amount of force trying to move those pieces.  As well it holds everything in place while you are welding.

[KRS]

At 3:00 he shows his die holder which might work for you

[iron quake]

Bolt on with two bolts works very well. I changed to bolt on dies in my 100 LB LG and never have a problem, and that's using 3/8 SHCS. The thing I like best about it is, I make tools steel dies welded to CRS base plates. The tool steel is small enough then that I can do the heat treating myself, but could't if I had the lower section with the dovetail as part of the die. I machine the tool steel portion heat and quench in oil if they are 4140 or air quench if they are S7. Tac weld the tool steel to the mild steel base plate. Pre heat the assembly to ~600 F, then weld the assembly together using .035 hard wire in a MIG. Then temper and stress relieve at 400-550F in the kitchen oven for an hour or two. Flux core wire or some stick alloy, would probably be better than what I use but it works for me.   

[macbruce]

I'd just bolt them on as well but if you do go down this road warpage of your base plate could be an issue. 

 

Yes, this will occur. I always put a slight bend in my across my baseplates before I weld them, this will insure if it doesn't pull back flat at least there is a slight concave face down, which is far better than the reverse

[PaulKrzysz]

Thank you everyone who contributed.

 

I will abandon the idea of using the Hex stock. 

I am in College for welding and they have a plasma cutter there which runs on tracks, it can be set at a angle to cut bevels. I might use that as a option to make the dovetails.

 

But from what everyone is saying, bolt on dies might also be a good option.

 

I will consider both and keep you guys updated on the build.

 

Thanks once again.

[Steve McCarthy]

Hopefully this attaches. It is an option for welding up dies.

 

 

let me try that again....

 

Well that didn't work either. Google the folowing:

 

WELDED POWER HAMMER DIES by Monty Bygd

 

 

[mike-hr]

I have a 1908 mechanical hammer with dovetails and wedges. I also built a new style Kinyon air hammer with (4) 1/2" bolts/die. I figured 4 is twice as much as 2, and two works fine. Everything previously mentioned is great advice. I would add, that if you want to do artsy, or industrial work, having the upper and lower pallets skookum in line is a good thing. Dovetails and wedges will take some flitzing with to achieve alignment each time, so you may lose in the big picture to changing 2 or 4 bolts per die and knowing they are where you want them. 

[patrick]

Double Keys-Yes, two keys of the same degee of taper driven in opposite directions will effectively hold a die with straight/parellel dovetail sides. That is how every Bradley I've ever seen was set up. I can't say that that method is any better from a function standpoint than the single key method, but it is easier to make and works very well indeed.

[BIGGUNDOCTOR]

Least expensive way to cut dovetails in a block is with a shaper. These dinosaurs are still out there in shops because of jobs like this. Machining them would make for a nicer end product.

[PaulKrzysz]

How exactly do you remove the keys in a double key system? Do the keys need to be long enough to stick out both ends?

[patrick]

Double Keys- One goes on each side of the die. That way only one end has to stick out beyond the die, thought in reality my keys are long enough for both to stick out a few inches. It's not a problem though because they are space apart by whatever the width of the die dovetail is so you can easily hit just one. Because the dies on a Bradley are oriented in line with the long axis of the hammer, you can really only access them from one side which means I strike one to tighten and the other to loosen. For  hammer that has easy access on both side you could set up one long key for both tightening and loosening and a short key just to provide the matching taper.