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I Forge Iron

Swages for Refflinghaus.

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New swage..  I've got a bunch to make.. 1/4" up to 1" but started with 3/8" because it's a common size. 

I prefer my swages the full width of the anvils face and a straight snug fitting shank.. I work off the edge of the anvil hitting back into the swage so find this design keeps the swage from lifting in the hardie hole. 

By extending to the edge of the anvil it also allows for a leg to drop down the side of anvil if need be. 

The Photos are a little skewed so the swage looks a lot longer than the face..  it's maybe 1/8" longer on one side.  




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Thanks..  I cheat on these..   Jump welds or Tee welds are tough in mild steel especially by yourself.   (wrought iron is so much easier).. 

The shanks are forged to just oversize of the hardie hole. Then cleaned up to bear metal and chamfered on one end (chamfered both but one is forged only). Then the swage body is cleaned in the center section and Electric arc welding the swage body and cleaned chamfer end.  I weld all the way around with a good solid bead. 

I then heat it up, flux it  (flux isn't needed really but old habits). and take a full welding heat, and do the jump weld while it is being fitted to the hardie hole..  

I then taper up the top (about half way up the swage body) and do a quick level, as it will need to be leveled a few times with a flatter.   ( When the round bar is driven in to form the round it will swell and push back out the taper and make it square again)..   ( Do just enough taper taking in consideration the amount of metal that will be pushed back when grooved)..

I have found that if I only work the cold mild steel round bar in one spot while forging in the groove it will naturally take on the Oval shape instead of round for the swage groove.  So it will end up that just slight oversized roundish needed so the swaging will come out correct without the sharp cuts in the swaged round. 

After a few, it's amazing how fast the process becomes.  then I do a quick filing for finish,  and will do the carbon uptake and will harden..  There will be a slight decarb that can be left on.. 

I know you didn't want or need all the info but figured others might find it interesting.. 

So simply I cheat..   I don't cheat on hardies  and forge the shanks integral and also on tools like bicks and such..   Swages because of how wide I have found it's the fastest method. 

One can use any steel this way too or even weld on a carbon steel to the mild before a shank is applied which is easier. 


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I don't know why you think I wouldn't be interested in the process you use.  I find it fascinating to get all the details.  Right now when I  need to use a swage for, say, tong handles, I just use my swage block, but eventually I may want to make some custom swages, and knowing your method is very helpful.  Thanks for taking the time to go through it in detail.  You are extremely generous with your expertise.

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  • 1 month later...

They will not last as long out of mild steel, but hot steel is much softer the mild. They should last a good amount of time if you aren’t working tool steels and keeping the stock hot. The other thing to note in JLP’s Video, she goes into detail about how she is raising the carbon content and hardening the stages.


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2 hours ago, tom_ET said:

Did i understand right that this is all mild steel?

excuse me if that is a silly question but does that mean generay that bottom and top tools (if not for cutting and punching) are ok in mild steel?

Yes,  Goods all ready pointed this out..  Because they are used with hot steels they work great.   With the carbon uptake method used they rockwell HRc in the 30+ range and as high as 60HRc with a surface hardness. 

If used as they should with hot metal there is very little if any chance of damage to the swage in use. 

If using them for production one can do a longer carbon uptake and get greater carbon penetration depth with nothing more than the forge.  I have several that have a few hundered Tenons on them with no wear. 

Today if I am doing extreme work with them, like a bunch of cold work I will test them with a dent test..  If they dent with a ball peen or bob punch struck lightly and in a place that will not throw a shard I won't bother with making one out of a steel faced or HC or medium carbon steels. 

The tools that really work best with solid or faced is/ Are set tools where the corners  take a beating.    And or  Straight, cold and hot hardies. 

The carbon uptake method works for top tools too.. 

Something that has not been  mentioned is..  Swages for proper use are made in sets..   The ideal being that in use when the top and bottom swage meet(make contact on the sides, the item is the correct size.  So this butting effect is the correct size.. 

One of the wear aspects of swages is the centers will wear inwards because the scale will pool in the center of the swage.. The Nice thing about these kinds of swages is they are easy to dress and nearly infinite life span with simply heating up, hitting it with a flatter to set the sides a little lower, run up the heat and do the carbon uptake again and for all intensive purposes. 

You now have a new swage with another few thousand tenons wear wise.   Also the more the swages are used the better they get.   

Erosion wear is really the only major factor and with proper use is not a problem at all.  

If you use a hard piece of steel in the swage it will deform some vs chipping, but I don't work that way anyhow..  Swages are for hot work. 

So I did do the video.. 


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Here is hardly any carbon steel available. You will be mostly limited to the 2nd hand car (and other) parts market. That will be probably fine but i suppose it is nice sometimes to buy a specific srandardized size.


so we have that version of packing the piece into the charcoal, salt, flour mixture and I think yours works without.

It was mentioned that there is the oxidizing, the neutral and the carbonizong zone. I would have thought that you would stick the piece int he upper part of the pile and leave it there longer.

thats bit really what you do, right? i think you heat it up 2-3 times till almost burning. do you quench it every of the 3 times or only the last time?

you heat that in the normal neutral working zone or in the upper layer?

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Have you ever burnt a piece of low carbon steel and thrusted it into water hoping to save it and it hardened? 

 I use soft coal..  Not sure of the exact process with charcoal as it should work nearly the same but won't have the additional green coal step. 

I use a well built slightly mounded open faced fire so there is ample fuel on top of the fire.   Insert the piece I want and bring the heat up..  As I am heating the piece I move it around till I find an even heat spot and open up a litte drop shoot on each side of the item..  this is to drop green coal into. 

the item is put into the carbonizing (reducing) area of the fire and brought up to as high a heat as it can stand without melting any of it.  it will look watery (and then grainy) just like in a welding heat.. I then hold it there and reduce the blast and throw in a few little piece of green coal and shut the blast off completely.  some little spark are ok, but try to avoid them.       I do this heat soak with green coal addition several times depending on how thick a skin I want.   ( each green coal addition is another carbonizing time and I only add a few small pieces)  Its really cool to watch because you can see the gases move around inside the fire. 

For the swages I do the high heat cycle 3 times and on the 3rd time I add the green coal.  Ideally always looking for a spot in the fire that will give an even heat.

The carbon monoxide  at that temp will help to carbonize the steel some..   30HRC and up is typical in a thin skin..  I once did this 3 times and it ended up about 60HRc..  (about 15mins total in fire time).  the thinner the item the more penetration for a given time frame.

The problem with this method is the grain growth runs out of control..  I quench from that yellow heat and move the block around as quickly as possible cooling it off to touch in "Water".  Usually straight up and down with large motion and quick enough not to form bubbles from the movement.  It will take some time to experiment but works for me every time. 

The problem I had early on was figuring out how to do it without melting off some section of the metal. I also stopped refining the method once I landed on a spot that worked for what I wanted.. I imagine with refinement of the method other things would be possible, just never bothered.  Might be something to look at now. 

  For swages and even hammers it can work well if one does not care about grain size. 

I never bothered to refine the grain though I have made knives with this method as a demonstration. 

My usual long winded explanation..     Let me know how it works for you or if you have other questions.  I'll try to keep it shorter. 

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Basically case hardening without the case.  Like most chemical reactions there is a heavy time & temperature factor involved, and the issue with grain growth has already been mentioned.

In general smithing you often scale off the surface faster than carbon can sink into it which is why every piece doesn't end up carburized.

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Thomas, I had looked at this very factor you mention with time vs scale factor..    As long as the temperature got high enough, it did not seem to matter.. thick, thin, long, short.  The largest factor is how much clinker is on the bottom of the forge fire..  I always seem to do this uptake just before shutting down for the day and slag can be a huge problem as the steel cooks it has an affinity to suck up the slag which binds tenaciously. 

The result are exactly the same with the mild steels I have tried.. 

All the research I have looked for and at say that mild steel should harden even at 1018 and especially at A36 carbon content..  Despite the information shown. I could never make the methods or the information presented work as a baseline quench as predicted or speculated in books. 

It wasn't until my buddy burnt up that mild steel knife and myself having burnt up several sections of nail making rods that when testing them with a file after trying to save them from burning up complete by cooling off quickly that they became extremely hard. 60+HRc

the higher the heat and the longer exposure the harder they became..   I then started to experiment with how to keep them at the high temps without having them melt..  This was the hard part.. 

They will harden even without the additional green coal addition.. I just started doing that because of information read about gases being more permeable.. 

I should at some point see what I can really achieve with it, but haven't bothered.   Maybe a plan for the future to see exactly how deep the skin is and then to see what is really happening with an acid etch. 


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There is a book..."The Cementation of Iron and Steel", Federico Giolitti;  that goes into great detail about a lot of experiments on infusing carbon into iron and steel:  Does CO need to be present? No but it helps. Can you use diamonds as a carbon donor? Yes. Etc & so on... It might contain some of the information you are wondering about.

It's also discussed in "Steelmaking before Bessemer, vol 1: Blister Steel" , Kenneth Charles Barraclough. (I was introduced to this book at Quad-State when Ric Furrer did his "3 ways of making steel" demo.  I ordered a copy as soon as I returned home from Q-S, I hadn't even taken off my jacket! I think I got the last "cheap" copy too.)

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Thanks for the information on the books..  I love you share that info.   I have added a number of books to my library upon your suggestion..  Thank you. 

I find that I like to develop my own understanding as a way of having it. (book learnin vs real world application).  It's how I figured this out and then read about why it works.  Now  I have a pretty good understanding of what is going on, so can change the results to what i want.. Harder in one area vs another,  thicker, etc, etc. 

 In my 8-10 years old days,  I've read numerous books on it where a smith in the old days would shove a bar into the carbonizing (reducing) zone to add carbon, and even in the early days, it was considered a normal concept to stuff iron into a forge fire and have it pick up carbon..  When I first started I never really understood how that could even be possible unless the iron was indeed melted as a way to pick up carbon.  (because of the decarb ratio). But conceptually could never see about forging that lump of burnt metal (melted) back into a usable bar. 

When I talk about experimenting it's more for others than for myself..  I won't devote the time to just do it. I need something behind it to drive the research.. 

The idea that using this "carbon uptake"  does work is shun but many for good reason if we come back to the "Mystery metal or Unknown " steels. 

There are many methods which were left behind as modern methods came about.   It is really cool how it works an how easy it really is.  

I ordered the 2 books you mentioned..  Thank you. 

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