Forging flat to round

[ofafeather]

I did a bit of experimenting in trying to make a pintle. I wanted to see if I could take 1/4 x 1 flat stock and use that to make a 1 piece pintle for a strap hinge. I left the stock long so I wouldn't have to use tongs. I made a fuller using the edge of the anvil a few inches in from the end of the stock. I then went to work reducing the stock to square from the fuller notch to the end. In form, it work out fairly well but the top and bottom edges if the stock seem to thicken more than the sides. The problem is that going to octagon then round left recessed cold shuts legnthwise in the stock. Is there a way to avoid this? Also, I would like to make a 90 degree bend and then have a shoulder from the pin. While I was able to form the 90, I can't get it sharp and didn't manage to come up with a good way to make a shoulder to have a smooth bearing surface for the bottom of the barrel of the strap to pivot on.

Any input would be greatly appreciated.

BTW, I was moderately successful. I did forge it down to ~3/8" round to fit the barrel of the strap I made.

Thanks.

Eric

[bigfootnampa]

It takes a lot of patience. You have to work very hot with many reheats and upset gently (you ARE upsetting the metal edgewise). It is easier (IMO) to start with thicker stock... say 3/8" X 3/4" or even round stock. For me it is easier to draw down than to upset. It CAN be done your way, but is NOT easy.

[ofafeather]

I just was speculating with my wife as to whether it would be better forging from round stock. I haven't gotten the hang of upsetting yet and didn't really consider that that's what I was doing. I believe the stock was hot enough. It moved so easily so it sounds like I was putting too much into it.

God bless this forum and all it's contributors. It's really great to be able to get guidance quickly when you need it.

Thanks, bigfootnampa.

Eric

[fciron]

I just was speculating with my wife as to whether it would be better forging from round stock. I haven't gotten the hang of upsetting yet and didn't really consider that that's what I was doing. I believe the stock was hot enough. It moved so easily so it sounds like I was putting too much into it.

God bless this forum and all it's contributors. It's really great to be able to get guidance quickly when you need it.

Thanks, bigfootnampa.

Eric

You should be able to flatten 1/4 x 1" flat into 3/8" round without too much trouble. The trick is to address that edge thickening early. I will dress those thickened edges back in by hammering on the wide face at the end of each heat. You want to maintain a rectangular profile all the way through the process. (It seems counterintuitive to hammer on the flat face when you want the bar to thicken, but the edge thickening has to be fixed to avoid cold shuts.)

Very hot steel and very solid blows will help the blow to penetrate to the center of the bar, but some corrective hammering is inevitable. If you can work over a fuller that will also help because it concentrates the blow in a smaller section of the bar. If the part you're reducing is long enough you might try working over the horn.

My 2 cents.

Lewis

[ofafeather]

You should be able to flatten 1/4 x 1" flat into 3/8" round without too much trouble. The trick is to address that edge thickening early. I will dress those thickened edges back in by hammering on the wide face at the end of each heat. You want to maintain a rectangular profile all the way through the process. (It seems counterintuitive to hammer on the flat face when you want the bar to thicken, but the edge thickening has to be fixed to avoid cold shuts.)

Very hot steel and very solid blows will help the blow to penetrate to the center of the bar, but some corrective hammering is inevitable. If you can work over a fuller that will also help because it concentrates the blow in a smaller section of the bar. If the part you're reducing is long enough you might try working over the horn.

My 2 cents.

Lewis

Interesting. Yeah, seems counterintuitive but I did feel the need to do a small amount anyway. I'll try it over the horn to see how that works. I did 5" or so section. Ended up being much more than I would need but I figured it was better to be longer than shorter. It work out pretty well for the 3/8" diameter though.

[peacock]

Try taking a good heat then put the bar in a vise edges to the jaws tighten it up for a short time till you see the edges cool a little take it out then to the anvil and go to work. With the middle of the bar hotter than the edges it will move first, then the heat will start to soak back to the edges. I have never done this at the hammer and anvil, but I do it with a power hammer often, just set the flat dies on it till the edges cool then get after it. It will save a couple of heats. Phil

[fciron]

Try taking a good heat then put the bar in a vise edges to the jaws tighten it up for a short time till you see the edges cool a little take it out then to the anvil and go to work. With the middle of the bar cooler hotter it will move first, then the heat will start to soak back to the edges. I have never done this at the hammer and anvil, but I do it with a power hammer often, just set the flat dies on it till the edges cool then get after it. It will save a couple of heats. Phil

Fixed typo. Middle of the bar hotter and it should move first. I have also seen the vise used to create a cleaner shoulder in the bar too. I might try that, 1/4 x 1 can be a little small for extra steps.

[Frank Turley]

It's good to be innovative, but you don't want to shoot yourself in the foot. You might try thinking about the old timer's way.

The forge welded pintle was probably the most used way because it gave you a bearing surface for the hinge barrel. It takes practice to get it right. Let's assume the hinge is of 3/16" thick material.

I do it in two steps, first welding a loop on 5/16" x 3/4", not unlike a hinge barrel weld. I normally drift for a 7/16" or 1/2" pin, although 3/8" would work for a lighter door. For the pin, I put a tiny upset on one end to keep the pin from falling through the hole. The pin is inserted leaving about 1/8" of the upset end protruding. I like to weld first over the radius of the anvil using various angled backing-up blows into the far side of the anvil. Then I'll drop the pin through the pritchel hole or an appropriate bolster and work the upset portion into the boss. It usually takes more than one welding heat. This second weld is what Schwarzkopf terms a "pin weld."

I've seen a few old pintles that looked to be made of square stock, bent and unwelded. I've tried this a few times. Using 1/2" square stock, I forged the pintle to a round section, finished between swages. I bent to 90º at the sectional transition. You do get a radius bend which is a bit difficult to square up with an upset corner. A few friction blows will help it a little. On a couple of old ones that I've seen, the corner of a set hammer was used at one side of the bend. This pulled enough stock into the outside corner that it could be trued up and squared up with a few hammer licks. It that way, it would be easier to install with the hammer, as you're now hitting a square corner rather than a radiused corner. Now, you only have a bearing surface on the square bar, which latter by the way, had been forged into a spike. I have one pintle like that in my collection that has a 1/8" deep wear pattern. Apparently these bent pintles worked, even though they didn't provide a full bearing surface.

I had a friend who wanted to try forging the bearing surface/boss and spike and then punching a hole rather than welding up a loop. He gave it up when he saw how much time that it entailed.

http://www.turleyforge.com Granddaddy of Blacksmith Schools

[ofafeather]

Frank, as always, thanks for your detailed and thorough post. I especially like the historical perspective. At this point I haven't actually had any experience forge welding. I have been mostly doing small things to getting used to the way metal moves. Your description makes it sounds easy, though! Can you do the same process without actually welding or would it be too weak?

[Frank Turley]

ofafeather,

I suppose you could figure a way to arc weld or gas weld the pin in a coundersunk hole by filling the countersink with filler rod while fusing.

If you study old pieces, you can see how they are forge welded. In the colonial days, guys would make strap hinges and pintles day after day, and get paid piece-work. They would get skilled and speedy. I believe that an arc welded setup for a pintle would be slower than skilled forge welding.

Furthermore, in the colonial period, the pintle was termed a "hinge hook." Technically, "pintle" is a seafaring term.

Buena Suerte,
Frank Turley

http://www.turleyforge.com Granddaddy of Blacksmith Schools

[ThomasPowers]

I don't think that just wrapping the pin without welding would hold very long as the pin would "work" in the joint and gradually wear itself loose.

[ofafeather]

ofafeather,

I suppose you could figure a way to arc weld or gas weld the pin in a coundersunk hole by filling the countersink with filler rod while fusing.

If you study old pieces, you can see how they are forge welded. In the colonial days, guys would make strap hinges and pintles day after day, and get paid piece-work. They would get skilled and speedy. I believe that an arc welded setup for a pintle would be slower than skilled forge welding.

Furthermore, in the colonial period, the pintle was termed a "hinge hook." Technically, "pintle" is a seafaring term.

Buena Suerte,
Frank Turley

http://www.turleyforge.com Granddaddy of Blacksmith Schools

Thanks, Frank. Any suggestions for practicing forge welding? If I make a hinge hook in this manner and make a weld would I need to put a bevel on the end of the stock before rolling the barrel?

[ofafeather]

I don't think that just wrapping the pin without welding would hold very long as the pin would "work" in the joint and gradually wear itself loose.

I was afraid you'd say that. :(

[Don A]

Here's another great discussion we had on this subject some time ago:

Wrapped & welded pintles

There is a great illustration at post #20.

Don

[ofafeather]

Here's another great discussion we had on this subject some time ago:

Wrapped & welded pintles

There is a great illustration at post #20.

Don

Don, great thread. Thanks. Did you take pictures of the pintles you made?

[Don A]

Yes, here's one...

[ofafeather]

Yes, here's one...

That's really great. Are those notches on the spike to help it hold better?