tips on forge welding

[MattBower]

I recently started using a coal forge, and last night I made my first successful forge weld in coal. It was a real struggle, though. I'm finding it hard to keep fines from contaminating the flux while the steel heats. The solution last night, we eventually figured out, was to quickly wire brush the two sides of the joint on the way to the anvil (with the help of a buddy), but not all joint designs allow for that. So what's a more reliable solution to this problem? I could also use some pointers on making a proper coal welding fire. I was having a really hard time forming a beehive, which may be why I was having so much trouble keeping the joint clean: I had to put the work right down into the fire, in direct contact with coke. I just wasn't having much luck getting the outer layer of coal to form a shell.

One other side note: a couple times last night, during unsuccessful welding attempts, I hit the joint and heard a loud "pop" like a firecracker and felt the work jump a little in my hand. I'm assuming this was due to coke trapped in the joint burning as I tried to set the weld?

Edited December 29, 2012 by steve sells

[Ecart]

Can't speak for the welding failures as I'm backing up to work on basic blacksmithing skills myself. But I can say that I had one pop like that once that scared the daylights out of me. It was due to water on the anvil that superheated to vapor when the hot steel hit it and it kind of exploded when the hammer was applied.

[keithgartner]

Try wetting your green coal that will stick the fines together, make a deep, 7", clean fire, no clinker steel etc., add coked coal on top and green damp coal to form bee hive, use as little air as possible to slowly bring to welding heat, flux before heating and on the way to anvil, small amounts of flux, then gently tap to start weld, two or three taps then back in fire, about three heats progressively hitting harder. Try a weld every time you light a fire. Practice, practice, practise.

[keithgartner]

Also the popping is the flux oosing out of the joint.

[Archie Zietman]

Wet your coal, and let it coke into a mound. Then cut a little opening in the mound, and insert your metal into that opening. Then, before you put the two pieces together for a weld, flick them towards the ground. Most of the flux and contaminants will spatter on to the ground leaving you with hot, clean surfaces to stick together. If you are hammering to spray the flux out from the joint as well as weld the pieces, then you might either get flux and coal stuck in the joint, or you could hit it too hard and shear the weld. Also hotter is better, I never weld below a white heat (with very light taps, not smacks of the hammer). And clean (start a new fire/clean it out if you're welding) fire. Deeper is better.
Good luck!

Edited July 4, 2009 by Archie Zietman

[Frosty]

If you're getting coal fines in the joint you aren't building the fire correctly.

Start by cleaning out the fire pot and building a new fire. Use the coke from your last one as the base and pile the coal on the outside using wet fines to cap the mount. Leave an opening in the fines layer at the top of the mound so flames can flare and burn the smoke. Once you have the mound coked make an opening in the side several inches above the air blast Glenn has posted a diagram numerous times and I'm sure it's in the BPs somewhere but I don't have a link.

Begin heating the steel with a gentle air blast and when it's orange remove it, brush the joint vigorously, flux and return to the fire. Keep your air blast moderate, just enough the heart of the fire is a high yellow and gradually heat the steel till it disappears in the fire. Watch for any sparklers emerging from the top of the fire.

When the steel disappears or you see the first couple sparklers quickly remove the steel and GENTLY tap the joint together with a couple few light blows. Reflux and return to the fire. Repeat till the joint is closed.

At this time you can refine the weld and give it it's final shape.

Large bangs and showers of sprayed out flux will only happen when there is a large weld area, welding up flats in a billet for example. If you're getting loud pops, gunshot-like bangs and big sprays of flux and sparks from small cross section welds you are hitting it TOO HARD.

If your steel is properly scarfed, cleaned and fluxed in a clean properly build and aired fire the steel will almost weld itself.

Frosty

[Doug C]

As Mark Aspery has pointed out in the past and I have tried and successfully done, you do not need to build a bee hive. A good clean deep open fire will do the trick nicely. Also I have found that heating the pieces slowly so they are uniformly hot then bring to a welding heat seems to do nicely. I have started making a chain out of 3/8's round cut into 8 inch lengths and all but one link has been done in an open fire. The one time I could not get the weld to stick I had a big clinker in the belly of the fire. I removed it and all went well after that.

Also, Frosty hit it on the head: use a light touch when sticking the weld. I normally use a three pound hammer for forging. I use a 12 ounce ball peen for sticking the weld. Not that I have to but I am too much of an oaf to control the heavy hammer when welding. I just get too excited at the site of steel at a welding heat!

[Rob Browne]

I will back up what Doug said. I have never built a beehive but weld successfully in an open fire. It must be deep though.

[thecelticforge]

I have found that wearing dark safety glasses works best for me. I can look right into the fire and bring the temperature up slowly to ensure uniform heat on the work. Also, placing two fire bricks on each side of my fire pot has helped making that little "glory hole" (I think that is the word glass blowers use) that we all need to keep junk out of our welds.

[MattBower]

Thanks to all for your tips and suggestions.

Celticforge, can you explain a little more about the firebricks? I'm not sure I understand what they're doing for you.

[thecelticforge]

The fire bricks help give more of a furnace shape. Instead of my coke rolling off the side, the bricks allow the fire to be deeper.

[DennisG]

ok, I need to ask.......

how do you forge weld with one person?

I try doing the motion with cold steel, practicing the moves cold. I can not seem to figure this out and one or both pieces drop, move, misaligned. If I had tried these with hot pieces......ow ow ow OWOWOW.... lol....you get the picture.

any suggestions, videos to watch or something?

Thanks
DennisG

[Frosty]

Wire or tack weld them together is what I do.

If you're trying drop tong welds then the only way is practice practice practice.

Frosty

[chichi]

To learn about the color of the steel and its surface appearance (wet)at welding heat, practice doing an easier weld. Take 1" by 3/16 or 1/4 and fold an inch back on itslef, flux, heat and weld (faggot weld). You can take 1/4 round, forge a taper to a very fine point and use that to touch the metal when you think it is ready to weld. Let it touch the piece for a few seconds and it should stick. That is when you know it is ready to weld. Also, try to keep the piece level and covered. If you place the work toward the bottom of the fire, too much oxidation. Drop the tongs is too difficult starting out.
Keep trying and good luck.
chichi

[CBrann]

I thought I was the only one who used an 8 oz hammer to weld with... tappa tappa tappa... proper prep, scarfing, and fire as explained should work.... When my Dad and I were working out forge welding we tried it with a sledge... big bang and we set the dog smoldering... and she was 12 feet away.

2 or 3 heats to finish a weld are more than acceptable... deep carburizing fire ..low air.. and your parts in the top 1/3 of the fire should cut down on scaling and weld failure

good luck
cliff

[Frank Turley]

I've been forge welding for forty-five years. I don't know what a beehive is. Is that covering the hot coals with green coal? We used to call it a cave fire.

Wetting the fines has been mentioned. That helps. The fire should be deep (high), clean, and compact. The fire can be open, but you need at least 4" of coke under the work and 2" of coke on top. You will not be able to see the piece, unless you make a peephole with your fire rake. Making a peephole is permissable. The work can contact the coke directly. When the workpiece(s) disappear from view by turning the same color as the surrounding coke, a dazzling, bright yellowish white, you have just entered the welding heat. Depending of the size of the pieces, give them 5 to 10 more seconds of blast and bring them out. To get rid of the surface soup which is a mixture of moltenflux, molten scale, and dirt, hit the pieces against the anvil or shake them in mid air. The soup will fall on the floor. Working by yourself? Lap the pieces on the anvil. The far piece is usually lighter, so the the heavier one can lever down on it thereby holding it while you reach for your hammer. Use the near edge of the anvil as a fulcrum/rest. Have your left thumb on top of the heavy piece, if you are right handed. Apply pressure and lever down. Francis Whitaker made a neat support for the far piece. He necked down and forged about a 2.5" length of round M.S. to fit snugly into the pritchel hole. With a forging heat and the round end in the pritchel hole, he bent the long end, about 1.5', down to about 90

[MattBower]

Thanks for that detailed discussion, Frank. And yes, I think a beehive is the same thing as a "cave fire."

[DennisG]

Thank you Frank, very good explanation. Cut and paste time. Gonna keep a copy of the explanation near the forge.

[Francis Trez Cole]

Thanks Frank for your discription.

I take my regular fire place the metal to be welded on top pour more green coal on top of the metal. and wet. bring up to heat slowly pull out metal wire brush flux with borax and slide back into hole. Dome is formed. Heat metal to bright yellow remove sling excess flux toward floor and hit lightly and evenly make sure all areas are welded.

[Frank Turley]

Gerald, Thanks for the safety sheet information.

I didn't mention the force of hammer blows in my above post. It's been my experience to use relatively light hammer blows to start the weld, perhaps a half dozen or so. The key word here is "relative." A light blow on 3/4" square has more force than a light blow on 3/8" square. Speaking as a smith and not a metallurgist, I think the reason for the lighter blows is to obtain initial cohesion. Once the pieces cohere, you can hit harder. If you hit too hard right out of the fire, there is a chance for the scarf faces to "shear" (slide apart) rather than cohere. Some of us have experienced this in a lap weld where the piece on the other side of the anvil goes squirting across the room when hit. Sometimes it results from hitting the steel too hard. There are other reasons, of course; for example, scale and dirt may remain on the scarf, even though you have fluxed.

There is another flux on the market that I like: Black Magic.

A story. In 1982, I was domonstrating for the Quad State at the Studebaker Homestead in Tipp City, Ohio. I met the then-owner of the Anti-Borax Company, the guy who made Climax, Cherry Heat, and E-Z Weld. What was on their minds when they came up with those names? Do they have sexual connotations, or is it just me? Anyway, he said that all three brand names were just a ruse. They all came out of the same barrel. When he told me that, he laughed like hell. He said that some SWORE by Cherry Heat, saying that it was better that E-Z. Yet they were the same!

The owner said that when he purchased the company that the special slag they used was in a huge vat. The seller gave him a little slip of paper with the formula, just in case he might run out of his supply. There did come the day a number of years ago when he ran out. He tried to duplicate the slag to no avail. The formula on the paper was bogus! He was frantic. He contacted chemists and smiths who might be able to help him. For a few months, there was no supply coming to the retailers. Eventually, they figured out a workable formula for the flux, and somewhere along the line, the company was named Superior. It is true that the newer version of E-Z is not quite the same as the old, but I personally find that it works just as well.

Buena Suerte,
Frank Turley Turley Forge and Blacksmithing School : The Granddaddy of Blacksmithing Schools

[Borntoolate]

I haven't done many forge welds only about 1/2 dozen. today I was attempting to re-weld a forge weld that had opened up when I was drifting a hole. Long story short I hammered everything back together, fluxed welded, and fluxed and welded a bit more for good measure...

With two separate but 90 degree hammer blows I heard a "Snap" during this rewelding/repair process. (welds were for 4 square bars) There was flux/slag spray to the sides but it was a different and audible "snap" than any of the other forge welds I have done, which aren't many... The snap was kinda like a stick being broken. IT was just a different sound that I had not heard before.

Can anyone say what this means?

[Glenn]

It could be several things, such as some material between the weld and anvil, drop of sweat, coal dust, etc.

[Ferrous Beuler]

Could have been the demise of your shop gremlin if he suffered the misfortune of being caught in your weld just as the hammer fell.
If so then good for you!

Now you should enjoy nothing but good clean welds from now on because that little bugger is D-E-A-D. :)

[HWooldridge]

Most of my welds go "spat" or pop a little. The flux is fluid at that temp and is pushed out quickly with the hammer blow so you probably had a pocket where some was trapped. I've seen Dorothy Stiegler pull the pieces out and swing to the floor in a quick motion, which will throw a stream of flux but then her welds subsequently don't make any noise.

As a side note, try to always work a forge weld as hot as possible during subsequent ops because they can fail if hammered at a low temperature.

[iron woodrow]

i like to put a bit of spit on the anvil and make my weld on that... CRACK! entertains the on lookers and scares the crows away... :D