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I Forge Iron

Scarf for a forge weld


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I started this thread as a result of posting on a similar thread. I thought the subject warranted its own start.

There are many different types of scarf for forge welding. Some are regional (Germanic, UK or USA) and others favor a fuel source (coal, coke or propane) Still more are personal preferences. They all work, given the required practice!

Please feel free to offer your own renditions and why they work.

I favor the technique outlined below. It is the one that I have practiced and become familiar with and it is very user friendly for students. With more experience, you may change this scarf slightly by forming the step over a round edge and increasing its depth somewhat.

Let

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Edited by Mark Aspery
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On photo 1 b, What if both pieces are 10 inch long? would you set them flat on the anvil and strike from the end of one of the pieces ? Is that called a butt weld?


No I wouldn't.

I have a frame that sits in my (round) pritchel hole. It goes over the edge of the anvil and then turns 90 degree to parallel the anvil.

As the bar is round, I can swing the frame out to act as a stand during a weld of long or difficult stock.

I have an attachment (angle iron) that I can bolt to the frame to hold round stock securely.

You can see the end of the frame in the photograph. The arrow just shows me resting the other stock on the side of the anvil as I guide it into place.

A butt weld is an end to end weld.

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Edited by Mark Aspery
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I have varying statistics on drop the tong welds. Some times it's easy, most of the time it ain't. I'm currently a big fan of blind rivets. Drill a 1/8 inch hole through both scarfs, countersink a little bit, and pin together with a piece of gas welding rod. Now you only have one piece to work with in the fire. The rivet disappears during forge welding. Life's too short to get all stressed out.

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Excellent thread Mark.

Would you go into a bit more detail on the "wings"


Before we talk about the wings, Let's look at the four things that can effect the penetration of your hammer-blow into a piece of metal.
1.) How hard are you hitting?
2.) How hot is the metal?
3.) What is the nature of the metal -stainless vs bronze
4.) The location of your hammer blow - in the middle of the stock or at one end.

We know that we need to use light blows to unite a forge weld. We can use heavier blows once we are sure of the weld.

If I have a 4 x 4 block of steel 12 inches long and it is ALL hot - as hot as you like (sav liqued).
I want you to stand it on end and upset it into a cube using your hand hammer.
How much effect do you think you will have at the bottom of the bar.... Zip-nil-zilch-nada you get the idea.

So even though the bar is ALL hot, it can be argued that at some point it can act as its own anvil (the anvil effect)

As you use light blows to unite a weld I doubt that you are fully penetrating both pieces of steel. The bottom piece will be acting as an anvil.

The top piece will spread.

If the toe of your scarf is as wide as the bar to which it will be weled, then the toe will spread past the sides of the bottom bar due to the anvil effect - thus creating the wings.

A very pesky situation involving sharp intakes of breath and much gnashing of the teeth!
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Forge welding has always been a bug-a-boo for me. I'm better at it now than in years past but I always say a little prayer before going to the anvil. There are folks like Bob Patrick who can go anywhere and make a weld but I'm not one of those smiths.

I put a point on the tip of most of my scarfs - not a chisel edge but something like you would put on a poker; short and sharp. I started this because I often left a cold shut on a corner of a bar, which weakened it and left me yelling in Low German (very low). While perusing an old text, I saw an illustration of welding round irons together and the author recommended a short upset with a point. I tried it and immediately had better results because a point usually blends on the first heat since it doesn't chill as quickly as the corner of a chisel edge. Mark, it sounds like you are saying much the same thing about "wings" forming from too wide a scarf.

If the design will allow it, I also tack most everything with the MIG and then put it in the fire. I know that's a crutch but it evolved as a method to give me success at a time when I was experiencing a lot of failures; I finally figured out that many of my problems stemmed from using pretty dirty fuel and not cleaning the fire often enough. Depending on the size of the stock, I have found I can do 4 or 5 welds and then I really need to stop and clean the fire or the next one is at risk. This is where practice and knowing your materials comes in handy.

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If I can add just a bit-for me worked adding piece of soft steel(or even iron,if available) between them two pieces(to somehow mimick soldering).It works sometimes better and one doesn't need to upset ends.Handy especially when making plenty of rings.

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If I can add just a bit-for me worked adding piece of soft steel(or even iron,if available) between them two pieces(to somehow mimick soldering).It works sometimes better and one doesn't need to upset ends.Handy especially when making plenty of rings.


I would like to know how you do this. Is the soft iron a third piece or do you weld it to one of the other pieces first and then make the weld?
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Here is a photograph detailing the 'Anvil effect'.

A piece of 3/8 round was doubled back on itself and welded with the blows coming from one side only.

You are viewing the piece from the side that was resting upon the anvil.

Notice how the top side has spread more than the bottom.
This shows that the bottom was acting as an anvil for the top to move.

When we talk about the 'penetration of your blow' and 'working form all appropriate sides' this gives a clear example of why.

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Edited by Mark Aspery
Spullin
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using a seperate pice to weld without a scaph is used when welding heavy sections ,bring the job to a welding heat in one fire or use two fires if the job is to big to get in one ,then in another fire get a couple of say 1 ins sq bar to a welding heat at the same time to make a fillet , then get the two parts of the job on the anvil ends touching strike the tong end to jump them to gether and then drop the sq fillet on the diamond across the joint and weld it down cut the and off then roll the job over and set the other fillet in and drive it down cut it of and dress the weld over ,the weld will hold its heat as you are adding heat with the fillets , thats the way we welded anchor crowns .

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yes i still have some it was used for steeling tools it is like a fine wire mesh in a borax type flux the sheets are like toffe and you cut of a pice and place it between the joint at red heat then bring the heat up untill it melts and little sparks just show out of the joint well below a full welding heat ,then give it a light tap .

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great thread mark!! much appreciated thanks, i think i understand this anvil effect also would i be right in thinking that if i am just drawing a bar out and dont beat the top and bottom equally that the sides will be angled due to this?, as the top or bottom will have spread more, requiring corrective blows to square it up on the sides,
thanks again

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great thread mark!! much appreciated thanks, i think i understand this anvil effect also would i be right in thinking that if i am just drawing a bar out and dont beat the top and bottom equally that the sides will be angled due to this?, as the top or bottom will have spread more, requiring corrective blows to square it up on the sides,
thanks again


In essence yes, nice use of the information. - although I start to call this something else at this stage.
I call it penetration of your hammer blow and the work done.

Have you ever missed the steel and hit the anvil directly??
No -me neither!
But I have heard of it being done!
Apparently the hammer comes back at a great rate of knots...

So, stating the obvious, the only difference between hitting the hot steel and missing it ---is the hot steel.

That's how much energy the hot steel absorbs.

Let's say the you start your hammer swing with 10 units of energy - whatever that is.

Your blow hits the steel and the steel changes shape... you are loosing some of your energy.

Let's say, for example, that 5 units of energy make it to the anvil.

The anvil makes noise, maybe bounces a little or the scale bounces - all using your energy.

But the anvil has its 'moment' and throws back as much of the energy as it can back at you - let's say 4.5 units at this stage.

The steel is changing shape again and you get 3 units of energy make it back to the hammer and lift your hammer off the work. The re-bound.

So I hope that it can be seen that the hammer and the anvil both do different amounts of work.

If you want something to be centered or equal then you have to work from ALL appropriate sides - sometimes two sometime four or more.
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Working all sides on small stock makes forging slower and doesn't make any noticeable difference. With thin stock the force of the blow is affecting the metal from the top and bottom at so close to the same amount that you will not be able to see any extra movement the top makes in relation to the bottom. I am saying this because I worry someone will be spinning 1/4 inch material all the way around as they make a point which is awkward and unnecessary. With practice you will find how this information affects your forging. The heat of the metal makes a big difference in how the force of a blow goes through the steel. You can get sharp edges on steel stock working it at a lower heat while bowing the sides out and creating a softer appearance to the steel by working at a high heat. The force of your blows makes a difference in this as well. With a hand hammer it is probably important to work 1 inch square from all sides while with a power hammer it may not make a practical difference. This information is something to play with to make steel into exactly what you want.

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