Forge welding problems

[Beavers]

I've tried to do my homework.  I've watched the forge welding videos from Black Bear Forge, Dennis Frechette and Joey Van Der Steeg.  I read the sections on forge welding in the books I have and have searched back through the forum reading everything I could find on the subject.  From probably a hundred different blacksmiths I have read or watched 150 different ways to forge weld.  It's slightly confusing.  I'm hoping that I can describe the steps I'm using good enough that possibly somebody can help me trouble shoot where I'm going wrong. I'll try to provide all the details, please let me know if I missed something.

 

Forge:  JPOB.  My first attempt the fire pot was 3 1/2" x 8" and 2 1/2" deep

                         Second attempt I made the pot deeper to 3 1/2"

Air:  Manual mattress pump with a 3/4" tuyere .  The tuyere is angled down into the pot slightly and the bottom rests on the floor of the pot.

Fuel:  Charcoal, a mix of Royal Oak and homemade hardwood charcoal.  I have been mounding the charcoal about 2" deep over the top of the stock

Steel:  1/4" round hot  rolled from Home Depot

 

My first attempt:

I scored the bar and bent it back cold to do a faggot weld.  I bent it cold in the hopes of avoiding creating scale between the pieces.  I though I had some borax but it turned out that I was out, so no flux with this attempt. I started by heating the steel slowly, when it got to orange I started pumping as hard as I could.  Once the steel looked "shiny and melty" I pulled it and gave it a couple of hits.  On a scale of 1 to 10 with 10 being the hardest I could possibly hit I used about a 4. I brushed and then reheated the steel.  Second hits were harder, about a 6.  Brushed and reheated a third time with a couple of more hits.  This one wasn't even close to being welded. I was easily able to pull it apart with pliers.  After some further reading I think my problems were no flux and too much air.

 

My second attempt.

I bent the bar cold for a faggot weld.  I read multiple times that slow is faster so I backed way off on the air this time.  Hopefully the short video shows how much air I was using.  

I heated to orange heat, brushed and then applied 1/2 tsp. of Borax to each side of the joint.  The Borax I used was the laundry soap kind.  

I continued with a nice slow steady pumping until the steel matched the color of the coals and looked wet and melty.  I pulled from the forge and held it an 1/8" above the anvil as to not suck the heat. I hit it a couple of times as fast as I could at a 4 out of 10.  I didn't see any sparking from the steel, but there was a lot of molten material that flew when I hit.  I'm not sure if that was just the melted flux.

 I brushed and applied another 1/2 tsp. of Borax to each side before reheating.  I heated a total of 3 times, cleaning and fluxing before each one. On the second two heats I hit harder at about a 6 out of 10.

I think I got at least a partial weld with this attempt.  I was unable to pull it apart using vise grips, but when I put it in the vise and cranked on it, it pulled apart easily.

 

I'm including pics of my forge, the joint after attempted welding and what it looked like after I pulled it apart.  

Any tips of where I'm going wrong would be greatly appreciated!

 

 

[rockstar.esq]

Beavers,

I'm by no means a forge welding expert, I've watched the same videos that you mentioned. 

One thing that leaps out at me here is that 1/4" round doesn't have a lot of mass to retain heat.  I have a friend who took a 1" thick x 4" x 4" steel block and ground grooves of varying thickness on one side.  He welded a handle onto the 1" thickness at a right angle to the grooves so he could preheat the whole thing in his forge.  When he's trying to weld smaller stock, he puts the heated block on his anvil such that the grooves cross the anvil face, and the handle is out of the way.  The grooves constrain the smaller stock from moving apart while welding which is particularly important with round materials.  Being pre-heated, the block also gives him a bit more time to set the weld.  

I would also suggest that the depth of your fire might be insufficient to get a large enough neutral zone.  I don't use charcoal so I really don't know what would be ideal.  I will say that the Dennis Frechette stresses the importance of a large mounded fire.  Rowan Taylor has some great videos on it as well, he also builds what he calls a "mole hill" fire.   Both of them appear to be burning coal.  It's hard to say just how deep it really is, but Dennis is using a bottom blast with a fire pot and two courses of fire bricks to make it deeper.  That's probably pushing 6" deep at stock level with lit fuel perhaps an inch above that.  Rowan Taylor is using a bottom blast, but the "mole hill" looks to be approximately that high as well.  They're not heating it like a rotisserie, they're surrounding the stock in a neutral fire.  You might accomplish this by adding one more course of bricks to your "pot"  depth then making a flat surface to mound the fuel over the pot.  Any heated stock that's not covered by the neutral zone is likely to scale faster.

A lot of videos are edited for time.  Getting that much fuel cleanly burning isn't a short process, although I suppose charcoal would be less time consuming than coking coal would be.  As for judging temperature, I met a farrier who offered a handy tip about forge welding outside.  He said that the steel is the right temperature when it "matches" the fire.  That's proven to be fairly accurate whether I was working in direct sunlight or in the shadows.    However, there's one significant caveat.  If you stop airflow for a moment and the stock immediately has a shadow, you're not quite to temperature in the core.  

 

 

[Charles R. Stevens]

Ok, one you probbably have A36, a structural grade of steel and depending on exactly what scrap it’s made from it may be an ally that doesn’t like to forge weld.

second you need to turn the top two bricks on edge so you can get a more fuel over the stock and it will stay in the table.

third, cold rold already has scale on it. 

Third use flux when starting out even tho charcoal is cleaner

forth think of heating like roasting a marshmallow. Roast it slow (pump the bellows like your looking for forging heat and let the stock soak so you get it hot all the way threw. Then pump the bellows like your hair is on fire to get that last bit of heat to bring it to welding heat (not sparklers)

last don’t hesitate, don’t rest the stock on the anvil, hover it over the anvil and drive it to the anvil with your hammer. 

Last last, don’t try and smash it flat, hit it firm, with a larger hammer to drive the pieces to gether, then to forge the two round surfaces together as flat surfaces. Typically we repeat the welding proses three times to insure good molecular transfer.

 

[Steve Sells]

20 mule team is pure borax and it works as a flux,

borax soap is not going to work they are different remember what terms we use matters

[Beavers]

Thanks for the feedback guys.  You've given me a lot things to try.

Any thoughts on how much air I'm using in the video?  Too much...too little?

 

Steve this is the Borax I used.  It only listed one ingredient...some scientific name I don't remember.

 

[Daswulf]

Beavers, I struggled at first with forge welding too. It's one of those things that once you get all the steps correct you get a good weld and an "Ah Hah!" Moment. 

One additional problem you may be facing is trying to faggot weld round to round. Square the area you are going to weld and scarf the end so it will transition to the rest of the bar instead of being a 90° when folded over itself. Heat the area while still straight to a good red heat and wire brush the snot out of it. Bend it at about a 90° wire brush again and flux and fold it over snug, all at a red heat.  Get it at a welding heat and quickly to the anvil for a few light taps to set it, talking about a 1 on your scale. Then wire brush, reflux and back in the forge for another welding heat then some more little heavier taps along the piece.  Continue with one more welding heat. 

I Know Im not good at explaining this but I hope its a little helpful along with the other good advice given. 

[ThomasPowers]

I'm with CRS; I've run into some bars that just don't want to weld and I've been forge welding on a regular basis since the early '80's.

20 Mule Team Borax is borax; watch out for things like Boraxo which is a soap with borax in it.

[Beavers]

Daswulf your explanation does make sense..thanks.

I'm going to stop at the local welding shop and see if I can get some 1018 1/2" square bar.  

There's a local hammer in a few weeks from now.  I'm guessing this is one of those things that is much better to learn in person.  If I can't get it figured out before then hopefully someone there will be able to help me.

Wow Thomas...you were forge welding back when I was in diapers. 

[stevomiller]

Daswulfs is the way I learned from my mentor, round on round is tough, especially in smallstock unless it’s a say a bundle that’s either wired or tack welded first (for a basket type, although square is still way easier). 

The idea of a heated block isn’t one I ever used but it could buy you a few seconds which can help.

Charles and Rockstar are correct make your fire deeper to get into a neutral environment. 

If you are just playing and trying to get s feel of the dynamics start with square or flat stock that’s a little bigger than you are using . Since it’s easier you can concentrate on proper heat etc. I’d even say take some scrap the same size as you want to weld, heat and wire brush and flux and take it up until you see just ones twosy sparks come off of it. When you weld low carbon you want to stop just before that color/point. As you get better you can go down in heat some and still weld, and better, but starting hotter was easier for me.

[Beavers]

Thanks Stevomiller

After a few phone calls I was able to find a place that sells small quantities of 1018. I got 1/2" round since it was half the price of square. I will square it up before welding.

I have zero confidence in my fire management skills at this point. I've exclusively used 1/4" and I've been able to get it to yellow, but based on the amount of scale I've been getting I think I've been using too much air. I've never been able to get sparks. 

I'll definately follow your suggestion and cut a chunk off my 1018 and experiment with fuel/air amounts until I can get it sparking.  That would at least give me a baseline that I could then back off from a little for welding.

Side note: Thanks to Joey Van Der Steeg's video I have learned that I'm using the wrong kind of brush to remove scale. I've been using a wimpy little one from the hardware store.  I just ordered one of the heavy duty flat bristled ones tonight. Hopefully between the better brush and better fire management I can reduce the scale problem I've been having. 

[dickb]

Try a much deeper fire and 1/2 inch square bar is probably a little easier to forge weld.  It has more mass than 1/2 inch round and sourced at the right origin it's the cheapest . The larger mass will make it cool a little slower. Try local companies that make railings. It's hot rolled and will come with some mill scale that you can take off with a grinder/file/sandpaper. 

You want to heat the work just up to the point that the (20 mule team) borax will melt, doesn't need to be any hotter. You have to work quickly when you go to tack weld it because it cools pretty fast. You can check if it's up to welding temperature by touching a piece of coat hanger to the work. If it sticks, then you are probably up to welding heat. 

Forge welding takes a lot of trial and error if you are working alone. Try to find a blacksmith in your area and ask hit ti show you how. 

 

[rockstar.esq]

Beavers,

Getting a lot of scale is pretty clear indicator that your stock is too low in the fire.  Smaller fires have smaller zones for oxidizing, neutral, and carbonizing.  Fire management is more than fishing out clinkers, and adding fuel.  If the burning fuel isn't consolidated, the air supply can and will blow past the fuel.  Depending on your situation it can give you a few telltale problems.  The most common is a fire that won't heat the stock no matter how hard you're blowing.  If the volume of oxygen isn't getting used for combustion, it'll actually blow a cold spot in the fire.  Another fairly common problem at the opposite end of the spectrum is to have a situation where the oxygen flow is so localized that it acts like a cutting torch.  That one is super frustrating because the rest of the fire isn't hot enough to efficiently get the metal up to temperature.  Since flux, clinker, and ash generally collect over a forging session, this tends to happen after you've had a chance to get tired.  So there you are, checking the stock periodically and it's just taking a long time to get hot.  One minute the steel is barely glowing, the next, you're pulling a sparking stump out of the fire.  It felt like any time I got 95% of the way done with my project, the "good bit" would get burned off on that last heat.

Unless you're going for an igloo fire, the solution is to tap the top of your fire down a bit with something fairly broad like a paddle or a shovel.  Listen to the fire under airflow.  If it's muffled or whistling, the airflow might be choked off.  I slide a straight poker along the edge of the fire and gently lift as I'm supplying air.  Charcoal doesn't form clinker so you should be able to hear when the fire takes off.  The heart of the fire grows much faster.  1/4" stock is pretty small stuff.  It should get white hot in a few minutes when the fire is working like it should.

Again, if your fire is deep enough, you can get stock in the neutral zone to white hot without it scaling in the fire.   

Finally, I use a side blast forge with a sand box.  I dig a 1" deep x 3" wide hole just in front of the tuyere before building the fire.  As the coked coal burns, the ash and clinker collect in that hole.  It takes a few hours before I have to pry up the fire to increase airflow.  If you set your tuyere pipe a little off the bottom, you might achieve the same result.

[ThomasPowers]

I learned from an old smith to use a slice to work the fire when welding to keep the "lid on" but shove it down at an angle on the sides  to push fresh coke into the burning zone .  (Slice is like a large spatula on the order of the typical fire rake)

[Beavers]

Thanks for all the info guys.

I'm going to step back from welding for a little while and concentrate on getting the fire management figured out. 

I'm going to a hammer in next month so hopefully I can get some in person learning.

[stevomiller]

Dick B are saying to apply the borax as soon as it will melt (about 1400*f), which I agree with to prevent scaling, or that it doesn’t need to be any hotter to weld than the temp the flux melts? I was never super consistent in butt welds and scarfed lap joints, but captured welds or flat lams or cable I was decent. I personally could not get low carbon steel to weld at 1400* . If however you are saying apply flux when it can melt, then bring up temps higher until a small thin piece of stock will still (like a coat hanger or leaf rake tine) then yes Iagree from experience. Either way not claiming you’re wrong, just that if you are welding at 1400* I couldn’t personally do it.

[eriktlupus]

Another source of the problem might be mixing in commercial briquettes.  The binders they use when forming will inhibit forge welding iirc.