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Welding forge build advice.


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This has been brought up a few times, and I'm grateful to the other posts that have helped me get this far! The time has come to build myself a forge, which I will need to be able to get up to welding heat. I'm blessed with a few things like a welding machine, so that gives me a few options other people don't have. So, here is my idea:

 

52899822009_6772d0938a_b.jpg

 

52899660501_3a917dfcfd_b.jpg

 

The plan is to orient the 8 fire bricks as you see above. Then the thick steel bar welded into a rectangle to support the bottom, and the thinner steel plates you see here welded to the sides, back and top to hold it together. Then the inside coated with the furnace cement (which I didn't realize was on the French side, but you get the idea!). I'm going to put together a blown forge, just as Geoff has recommended in this excellent post:

 

The only difference is that I'm going to use an old blow dryer for the impeller, since I have one on hand. I'm planning on having the outlet of the blower in the top right hand side of the forge, directed in straight (since a straight hole is easier to cut), and to hook it up to a propane tank. I also still have to buy the parts! I have a burner and a small furnace I use for melting copper, but I don't want to reuse the parts for that, since I'm afraid they may not be compatible with good welding. In particular, the burner is pretty huge. Works well for melting copper, but I'm afraid it will pull in too much oxygen. Here's the setup I have for that:

 

52899822054_b7ddc83c97_b.jpg

 

You can't really see the burner head, but it's pretty big, about 3-4 inches in diameter. 

 

So, I have some questions: 

 

-Initially, I was thinking of having some kaowool for a "door" covering, to help the forge lean towards reducing (with a gap in the side for safety!). However, if I'm using a blown forge, is this really necessary with the design I have? 

-I'm wondering if the forge is likely to be reducing the way it is, or if I should put in some cut up fire bricks to encourage the flame to pull into more of a circle? It would be a bit of extra work, but worth it if it would increase the reducing nature substantially.

-Any other comments about the design? I'm primarily going to forge wrought iron tsuba and other koshirae in this, so it doesn't need to be big. The trouble is wrought will fall apart too much if it isn't hot enough or reducing enough! Maybe in the future I'll try my hand at some knives. But if you guys think a different firebrick design would make more sense for wrought, I can try rearranging them (I have extras as you see here!). I have the facilities for cutting fire brick, but I don't want to spend a lot of time doing that! My wife doesn't want me using this in the garage, so I'll be doing most of my forging in the back yard. 

 

Thanks for your help!

 

 

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As you probably know, wrought iron needs relatively higher heats for forging.  It appears that you are planning on using "hard" firebrick for insulation of your forge.  This type of firebrick is more impervious to flux than some forge materials, which will help for a forge welding liner, but doesn't insulate all that well.  It will be a significant heat sink and bleed heat through conduction to the outer skin, which will result in a much less efficient forge.  The bricks may also not be suitable for the high temperature you are anticipating and the refractory cement is designed to fill gaps between hard refractory materials, not as a flame face or inner liner.  If it is anything like the refractory cement I am used to it will not be suitable.

 

There are much better forge liner alternatives.  Also, for a properly designed blown forge, doors are extremely helpful in improving efficiency (and typically need less gap than a similarly sized NA forge).  I wouldn't use loose refractory blanket for a door.  It breaks down into shorter fibers at the forge welding temperatures anticipated, and moving it around can release those fibers to where you can end up inhaling them.

 

Whether the forge is oxidizing or reducing depends almost entirely on your burner design and how it is mounted in the forge.  My recommendation is to find a successful design for both the forge and burner and copy it exactly.  You can certainly try to reinvent the wheel, but the required experimentation will take time and cost you more.

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I repeat what Dan said.  Use a real refractory, not those fire bricks, and not that cement.  The cement will peel off in one firing, and the bricks will crumble soon afterwards.  Get some Kast-O-Lite 30 and line a kaowool forge with that.  Use the bricks for the door.

 

If you were just trying to make knives and didn't need to run it at 2000+ degrees F, your design might work for a while.  As it is, it will not be able to get that hot.  

 

If you plan on using that galvanized steel as a frame, please observe all precautions when welding it, i.e. do it outdoors in a strong crosswind so you don't breathe the zinc fumes.  

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Another thought: Since you just want to make tsuba and other koshirae, why not just use the bricks to make a small charcoal forge? You can use the hair dryer as a blower for that.  Just build a trough out of the bricks, use the cement as very thin mortar, hold it all together with the steel frame (still don't breathe the fumes when you weld it!), and run a pipe from the hair dryer into one long side at the bottom.  Have it at least six inches / 15cm deep above the air inlet.  This will approximate an actual Japanese forge pretty well!  It will easily weld wrought iron, or even melt it for that matter.  It does get sparky, but unlike a gas forge if something goes wrong you can just dump a bucket of water on it and be done.  If you keep the iron near the top of the fire with a little charcoal on top it will be in the reduction zone.  

 

Just be sure to use lump charcoal, not briquettes. 

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I built a small, 2 brick forge out of soft brick to HT springs and things.  It just uses a plumbers torch and I tacked it together with a metal strapping frame.  It works, but not well.  The old standby design is an empty BBQ size propane tank with the ends cutoff.  The burner design from my post will drive that design up to 2500 F.  If you use Kaowool.  My welding forge is that idea, but 24 inches long.  I use 2 wraps of wool.  The first one goes in bare,  and the 2nd wrap of wool is soaked in mizzou (a refractory cement).  That gives you an efficient, insulated fire box (which your fire brick design isn't ).   It's pretty durable (my welding forge needs a reline, the last one was 3 years ago), easy to patch and will get to welding temps easily.

For a forge that size (BBQ tank) a 100 cfm (like a bathroom exhaust fan) is plenty.  I use a 100 cfm fan and have to close off 80% of the intake to run at forging temps.

 

g

"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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Thanks for all the input! Haha, it’s a good thing I didn’t try to make it. That’s noted about the zinc fumes, I’ll make sure to weld in good ventilation. I’ve only ever welded small things with the garage door open, hopefully I haven’t inhaled too much zinc so far!

 

So back to the drawing board, I think I’m just going to spring for the single burner Mr. Volcano. For that price, I don’t think I can go wrong. I’ll use my bricks to cover one end, and 2/3’s of the other end. I'll get some Kast-o-lite 30. I've bought from Canadian Forge and Farrier before, and they have some, so I think I'll go with that. I'll get the plus since I'll probably need a bit more work time (I work slowly on these things!)

 

I could make a charcoal forge, but I think it’s going to be too messy in the backyard for now. I like the idea of a charcoal forge though, and I definitely want to make a real Japanese one some day!

 

Now, I do have a question more from curiosity than anything. In the past I got some of this:

 

https://canadianforge.com/products/greenkleen-60-plus-castable?_pos=1&_sid=1914ad250&_ss=r

 

I diluted it pretty thin and used it to coat the kaowool from my copper melter. However, I also prepared the whole bucket, and now it’s solidified inside the bucket. I kept it though, figuring it could be useful. Do you guys know what the difference between this and the kast-o-lite 30 is? If I can just cut the solidified brick and use it instead of the Kast-o-lite in the Mr. Volcano it will save me a bit of money, but I have a feeling that would also be a bad idea!

 

 

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16 minutes ago, Carlos Lara said:

I'll get some Kast-o-lite 30

Everything you need is in the box with the forge, unless you are changing the angle of the burners and re-sculpting the inside like I did. I had Satanite and Mizzou on hand from other projects. First forge, probably best to build as intended.       https://www.facebook.com/groups/508682393939972

Matt Walker                https://www.youtube.com/@onedamascusmaker/videos

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Hard to beat for the price, I don't know about the performance, but everybody has to start somewhere.  The first gas forge I ever saw was a roll of kaowool, inside a roll of expanded metal mesh with a hubcap over the end.  The burner was a piece of pipe with a copper line directly from a 5 gal BBQ tank (no shutoff except the tank valve) and an old hair dryer for air.  Sketchy as hell, it glowed like a pumpkin at Halloween, but it did the job.

 

Be very careful of galvanized steel, when it gets hot it gives off a bright white flame.  A well respected smith in the NE died as a result of zinc fumes.  He know better, but he figured he could chuck the pieces in the forge and get out while the galvi burned off.  He was wrong.

 

g

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"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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I second you'd be better with a sheet metal shell with an innswool (high temperature ceramic insulation) layer(s) on the inside, coated with satanite or some other refractory.

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  • 3 weeks later...

Well, today was first time lighting the forge! It took a bit longer than I thought rigidizing, and coating with the two layers of satanite, but I got it done. There was a minimal amount of smoke the first time lighting it, then smooth sailing after that. Part of it was figuring out how to light the venturi burner! I ended up putting one brick on either side, and the forge did get quite hot! I had two small pieces of wrought to learn to forge with, and while they didn't quite get white hot, they got pretty close with a very bright orange, and enough to melt most of the scale off. That gave me at most about 30 seconds or so to hammer, though it was getting better all the time as the forge heated up, and as the anvil was getting warmed up too. I put them in the hot spot just past where the flame hits the firebrick, close to the wall, and that seems to do a good job of heating. So it's not perfect, but it's enough to get me going. A few hours a few times per week, and I'll get the tsuba blank made eventually!

 

While I'm working on this, I'm going to look into charcoal. There isn't really good charcoal available locally, so I'll have to look into making it. We have tons of scrap pallet wood to use for it though, so it shouldn't be too hard. That and making a Japanese style bellows, and I'll be good for both forging wrought iron, and to use as a finery furnace once I get it set up. 

 

52940459311_ae9e1b50f5_b.jpg

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If you take that brick off the floor it'll get hotter faster, and cool off faster when you're finished.  Just add a little more Satanite to the floor to resist scuffing from tongs.

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When people start talking about making charcoal, I ask this question.  Do you want to be a smith (making stuff out of metal) or do you want to be a charcoal maker.  In the day, they were both full time jobs.   Within broad limits, no one did both.  It took between 6 and 10 charcoal makers to keep a single smith in fuel for a year.  And charcoal makers were in turn supported by an army of hedgers and coppicers ( The people who tended the trees that made up the fuel source).

In addition, gas forges go back to the 1820's (during the first big oil booms in Pennsylvania).  The Japanese used charcoal because they really didn't have access to anything else.  And they had the same issues with deforestation that England had.

 

IMHO, a modern gas forge (properly tuned and setup) is ideal for the hobby smith (most of us).  It's fast to heat, it's simple to feed, it hardly annoys the neighbors.  Solid fuel has some advantages in flexibility of the size and shape of the fire, offset by the learning curve of tending a fire.

 

Rant mode off

 

g

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"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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Thanks Geoff,

 

Haha, you're probably right. I think my problem is I keep going over this site:

 

https://islandblacksmith.ca

 

and I just want to do everything dave does! But you're right the time to output in heat you get probably doesn't make sense for charcoal for the average user. That's probably also why he has trouble making a lot of knives! That and his attention to detail is very labour intensive. Those sure are gorgeous knives though! I guess what I should aim for is something in between, almost as nice as Dave's, but somewhat more realistic for me! (what I should really do is light up the forge more!)

Edited by Carlos Lara
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"Traditional" is a word that takes us down many rabbit holes.  Dave does fine work, however, no "traditional" maker made everything.  Sword and knife makers made blades, and did the initial polish, everything else was done by dedicated craftsmen.  No maker made his own steel, or charcoal, just as they did not make the silk for the handle wraps..

 

Blade making is a process, you learn a thing, you polish that skill, you learn another thing and polish that.  It's not a race or a competition, except with yourself.  I do what I do, and I try to add to my skill set as I go.   That is the best I can do.

 

Geoff

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"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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On 5/31/2023 at 9:15 AM, Carlos Lara said:

There isn't really good charcoal available locally, so I'll have to look into making it.

Here's basically how I do it with a couple minor mods. I spent a few years collecting scrap wood and a couple of weekends making charcoal. I made 160 pounds of the stuff and still have most of it.

 

 

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“So I'm lightin' out for the territory, ahead of the scared and the weak and the mean spirited, because Aunt Sally is fixin’ to adopt me and civilize me, and I can't stand it. I've been there before.”

The only bad experience is the one from which you learn nothing.  

 

Josh

http://www.dosgatosdesignsllc.com/#!

https://www.youtube.com/channel/UCdJMFMqnbLYqv965xd64vYg

J.States Bladesmith | Facebook

https://www.facebook.com/dos.gatos.71

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  • 4 weeks later...

I've been forging with the Mr. Volcano, and I've been very happy with it. I keep getting interrupted when I'm forging, so progress is slow, but I'm getting closer to a usable blank for making tsuba. One problem I have though is the fire bricks I use to help close off the ends. They work fine, but they keep falling over, the face melts, and they break. So I'd like a bit more stable solution. What I'm thinking is get some sheet steel, grind off the galvanization if necessary, and weld some boxes with one end open, line with kaowool and cover the open end with refractory. Then once I have these doors, find some way to hold them in place, maybe have some steel bars to connect them together and hold them at each end? Is there an easier way to go about this though? For instance, would thick steel sheet on each end be enough, or is the insulation really necessary? Thanks!

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I pulled these off the Web.  A quick search for gas forge with doors will find many pics of different solutions

 

20170115_140808.jpg

 

20170115_140751.jpg

 

G

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"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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Now that's cool!B)

 

Carlos, keep in mind that you're running a venturi burner.  Those need a good-sized exhaust port to work right, you can't close them up tight.  That's why people use the loose bricks, you can stand them (or prop them up) an inch or so from the forge door and they'll still reflect heat back into the forge while allowing exhaust gasses to exit without creating back pressure.  I like the designs that hang a brick (or other refractory) in a frame so that you can raise it to open the door and lower it to mostly close the door.  Those keep the heat in really well.

 

If the bricks are bothering you, look at insboard.  Rigid fiber matting.  Much less fragile than brick, lighter weight, and you can screw brackets or frames directly to it. Something like this: https://www.amazon.com/BXI-Ceramic-Fiber-Thermal-Insulation/dp/B07TG9H8DZ/ref=sr_1_6?keywords=ceramic+fiber+board&qid=1688578721&sr=8-6

 

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Thanks Geoff and Alan! I bought some of the ceramic matting you recommended Alan, and I think I'll try to make a frame and an articulated door like Geoff suggested. I'll leave a good sized gap in the doors on both ends so that the venturi burner is happy when they are closed. Appreciate the advice!

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