forge welding fire

[Nik Hintz]

Greetings all, I'm working on forge welding, but am definitely still on the uphill side of the learning curve. My best result thus far has been working with 3/8 round stock, making simple rings, so as to eliminate the variables of heating, moving, and aligning multiple parts, but the best weld has failed after 1 or 2 whacks with a 2# hammer. The test is done by cutting through the side of the ring opposite the weld, then clamping in a vise and hitting the free, cut end.
As far as I can tell, the flux is working, the failed weld face is bright and clean looking.
So on to the real question, how clean does the fire really need to be, will a bit of clinker stuck to the sides of the fire pot prevent a good weld, or am I just looking for something to blame other than my inexperience and poor technique.

Any thoughts or tips would be great; Nik

[Frosty]

Scarf the joint, clean, brush or file, flux when it's hot enough to melt the flux, bring to high yellow and don't hit it so hard, use a smaller hammer for instance. 2lbs. is pretty heavy for 3/8" rd.

Frosty the Lucky.

[thecelticforge]

I generally make it a rule that if it is worth welding once, it is worth welding twice. Every time I work on a welded joint I make sure it is a welding temp. Other here will tell you that it is not necessary but it works for me.

[John B]

As far as I can tell, the flux is working, the failed weld face is bright and clean looking.

Any thoughts or tips would be great; Nik

Hi Nik, the clue may be in the bright faces, you are not achieving a fusing heat, also probably hitting it too hard at the initial stage, and driving out, rather than amalgamating the joint.

Clean fires are desirable but not essential as is the use of flux

Keep trying, you need patience and a gentle touch to start the joining process, start where the molten flux if you are using it will be able to escape, the position and sequence of the hammer blows can make a difference, also don't make the scarfs too long.

Try again and good luck with it.

[Nik Hintz]

Thanks for the thoughts. To clarify, the 2# hammer was used for testing the weld, not setting it, and the flux is anhydrous borax I had left over from some silver casting.
Another thought I have is that I might not be getting things quite hot enough, has anyone ever tried mixing a little iron filing with the flux to act as an indicator of temp. I seem to recall reading about that somewhere, but my memory is far from perfect...

[John B]

Thanks for the thoughts. To clarify, the 2# hammer was used for testing the weld, not setting it, and the flux is anhydrous borax I had left over from some silver casting.
Another thought I have is that I might not be getting things quite hot enough, has anyone ever tried mixing a little iron filing with the flux to act as an indicator of temp. I seem to recall reading about that somewhere, but my memory is far from perfect...

It doesn't matter what you mix, the temperature can be judged by the sweaty /molten appearance of the metal in the forge, flux will give an impression of fluidity, but you don't NEED flux, its the metals temparature that is critical, some look for sparks coming from the material, but this is a very tight window as it can also mean you have exceeded the temperature required and gone beyond the point of no return.

Is it possible for you to contact another smith who can show you this? or join you local group, videos and descriptions are no substitute for seeing the actual process. 20 minutes and you should have got it.

[Bob S]

Greetings all, I'm working on forge welding, but am definitely still on the uphill side of the learning curve. My best result thus far has been working with 3/8 round stock,

Try a few welds using larger stock...say 3/4". Larger stock will stay at a welding heat longer and give you more time to sort out what is happening.

Bob

[Sam Thompson]

Look for the first few bursting sparks to fly out of the fire.
If you are using the 'drop the tongs' method, try, instead, just touching the ends of two lengthe of flat stock together in the fire; similar to the way suggested by Stewart (be careful most coathangers are usually galvanised). They should stick quite firmly and need to be wrung apart; this will give you a better idea of how to judge the rising temp.

[Nik Hintz]

Thanks again. I have tried a few more times, the results are improving, but I think seeing it done will help. I'm hoping someone at the NY designer blacksmiths meeting will be able to give a demo this weekend.

[Frank Turley]

You want the ring weld to be a side scarf weld for ease of handling, not a top scarf weld. For example, when you first bend downward over the horn or anvil side, have the scarf face to the right, not up or down. When the scarfs meet, the heel of one meets the point of the other. Have the scarfs touching, no gaps. You can't help but forge a cross section of square, octagonal, round (SOR). Coming out of the fire, you shake the ring in midair to let some of the "soup" fall on the floor. You start on the anvil face near the horn hitting both sides of the weld with light to moderate blows. When you get cohesion, you can hit harder. If you still have a welding heat, take it to the horn and hit the edge-shuts. If you still have a welding heat, begin to work on the diamond taking down the corners of the "square section." It can take up to five heats or so to get it right on mild steel. Avoid big shower of sparking heats. Try to use sweating heats with few or no sparks.

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