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Philderbeast

Buying a gas forge?

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I'm looking at buying a gas forge to get me started, my teacher has an NC Knife makers forge that i have been using for a while with some success so I'm looking at something similar for my own workshop to get me going can anyone recommend where i can get a forge?

 

I have been looking at a few places however getting a forge locally is proving to be expensive to say the least (at this stage it looks like i can import one for half the price!) so I'm looking to get the best bang for my buck with something that i can keep to use for many years to come.

 

thanks.

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Best to build your own. You did not say if you wanted blown or atmospheric.

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I second that. Either make your own or be ready to shell out a good bit of cash for a well made one.

 

If you've already got access to a forge, you can base your design off that, which will help a TON. If you have access to a welder, you should be able to make a forge easily of any dimensions you want, then lining it is pretty simple with your choice of liner. The only thing you have to worry about is a burner or two, which you should be able to buy for less than $75 pre-made, or make your own for less (very easy to make your own with just some pipe if you go with venturi (atmospheric) burners.

 

If you can't access a welder, find a cylindrical object and use it as the body, they work great and all you have to do is cut a few holes in it. I just made a forge with a 30 gallon drum and one blown burner, and I absolutely LOVE it. It works amazingly, and the satisfaction of building it myself was definitely worth the effort (not to mention it cost me under $200 ^_^ )

 

I made the huge mistake of paying only around $175 for a cheap knock-off of a very well made forge on ebay. It worked great for the first few months, then simply fell apart because it was made with materials not designed to withstand forging temperatures. I ended up rebuilding almost the entire forge, and wishing I had just made my own to start with.

 

Good luck!

 

-Dan

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Try looking here:

 

http://www.dfoggknives.com/forge.htm

 

You'll find that it's really easy to do, inexpensive, and makes a better bladesmithing forge than any of the commercially available models.

 

Folks here will help out with any questions. :)

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I have two blown gas forges up and running now. For one I used a large metal mailbox as a shell for it. It's lined with insulating ceramic matting and coated with a refractory cement. The second has the entire body cast from a castable refractory and the doors made from squares of insulating fire board. Both have blown burners that were made of material found at the local hardware store with the exception of the blower. Blowers need not cost all that much. Some of the discount supply houses carry them. You will need one for continuous use that puts out at least 60 cfpm. You might even be able to scrounge one for free from something like an old dryer.

 

Your instructor's forge may be called a knife maker's model but it has the same design as a general blacksmiths forge with the fire coming straight down onto the floor of the furnace. This will lead to hot spots on the blade when you go to heat treat. You will get a better knife maker's forge by building your own and you will spend less money doing it. If you don't want to make your own forge there are knife makers who also make and sell forges but you will have to pay for them to assemble one for you and ship it.

 

If an electricity supply is an issue for you then you can build a forge with a venturi burner.

 

Doug

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This fan is just about perfect. Elsewhere in old threads there are discussions about burners. I've posted in most of these, and the burner I use for all of my forges (3 right now) is built from black iron plumbing pipe. Do a search for forge design or burner design.

 

Geoff

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it looks like i might end up making the forge as i cant seem to get a decent one here.

 

I was thinking of going venturi burners as they seem simpler to make, whats the major advantages of using each? and can I change it from one to the other later if I decide to?

 

As for the issues with heat treating I'm looking at building a heat treating forge like the one Dee built in this thread later on when im making some more serious works ;) and the parts should be easy if i look at the same suppliers as she used

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I was thinking of going venturi burners as they seem simpler to make, whats the major advantages of using each? and can I change it from one to the other later if I decide to?

 

That's the classic mistake in thinking. A venturi has to be built exactly right or it won't work properly, must be balanced to the volume of the forge, are much more difficult to adjust to get a reducing atmosphere, and are generally a pain to keep in tune, at least with the home-built ones I've used. The T-rex burner is the exception, but they're pretty expensive. The only advantage of a venturi as far as I'm concerned is that they don't need electricity.

 

A blown burner needs no exact tolerances in construction, a slight misalignment of a pinhole jet is not a problem, they are easily adjusted for any atmosphere you want, and are pretty much a necessity if you want to do a lot welding without first spending hours learning how to tune a venturi that might not get hot enough anyway.

 

No doubt there are good venturis, but blown burners are just easier to build and adjust.

 

Whichever style you go with, the most important thing for blade work is to have the burner enter the forge at an angle so the flame will swirl. In a gas forge the flame is not what heats the work, it's the radiant heat off the walls of the forge that do the job. You should not be able to see a flame inside a properly made forge, just a uniform glow.

 

The NC forges are perhaps the absolute worst forge design for blade work ever invented. You get an oxidizing atmosphere no matter what; you get two or three hot spots of massively oxidizing flame directly on the work; and when you turn it off you get a chimney effect from the vertical burners that drastically reduces the life or the expensive venturi parts. They were designed for farriers as a horseshoe forge for making slight adjustments to factory shoes, and for that they're fine. The design is so inherently flawed for any other purpose it's not even funny.

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Oops, forgot to answer your other question: Yes, you can switch out burners no problem, just remember you don't want or need a tiny orifice for a blown burner since they don't rely on high pressure gas to work.

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call it like it is.... Yah !!!! B)

 

and to top it off.. they are expensive too !

 

 

jeez, mail box sounds just right

 

 

besides, you have to redo the lining anyway if you do damascus... so might aswell jump right in and make them ;)

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That's the classic mistake in thinking. A venturi has to be built exactly right or it won't work properly, must be balanced to the volume of the forge, are much more difficult to adjust to get a reducing atmosphere, and are generally a pain to keep in tune, at least with the home-built ones I've used. The T-rex burner is the exception, but they're pretty expensive. The only advantage of a venturi as far as I'm concerned is that they don't need electricity.

 

*snip*

 

glad I thought to ask before building then :) one thing i was thinking about was buying the burner and building the housing for it, as power is at a premium for me in the shed where ill be forging I'm happy to spend a bit to get a good burner for the forge. particular as i should be able to make some saving's compared to buying one by building it my self, as well as learning how to do the lining that i will no doubt need to re do as i have a goal to eventully make a pattern welded viking sword (in 5 - 10 years time, so I'm in no rush for that ;))

 

i have looked at a few burners so far, in particular the t rex (since you have mentioned it) and the Diablo Burner that seems to be similar from http://www.chileforge.com/

 

both are a fair whack from my budget but I'm not particularly comfortable with making this part of the forge so i think it will be worth the price.

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You won't go wrong with a T-Rex, they're great. I can't say anything about the Diablo burner since I haven't used one.

 

When you do build your forge, remember you can make a pattern-welded viking sword in a forge that only heats four inches at a time. You'll want something longer to heat treat it, but the actualy forging and welding is usually done in a small forge. B)

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My small forge, the one made of castable refractory, is only 7" deep with a pass through port. I could easily heat treat an 8-10" blade in it though I use the larger mailbox for for most of my heat treating. One of my projects this summer is to put a pass through port on the back of that forge so that I can heat treat blades longer than 14" as I want to make a langseax.

 

Doug

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If you have access to a drill press and some taps a side draft burner is easy to make. I can email you instructions if you like. A good forced air burner will be a bit more $ up front, but will be able to do anything you want. I like a larger blower than 60cfm since you can always reduce the amount of air using a valve. With a well insulated forge either type should be able to get up to welding temps.

 

Wayne

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Little Johnny Forge is around 500. Several guys from the Arkansas knifmakers Association are using them. Lin Rhea helped John get them set up right so its made by a knifemaker and tuned up by knifemaker. For a single burner blown forge made for hammering I would say its the best out there, you weld in it too but most everyone uses a second larger forge for welding because of the mess and larger size desired for billets. If you search there are pictures of it posted here on the forum,,,,,,,

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If you go to www.elliscustomknifeworks.com you will find a link to the person who bought the bussiness from them. I understand that he intends to offer everything that they did including horizontal and vertical forges as well as blown and venturi burners. I think that Riverside Machine Shop also sells a vertical forge designed for knife making.

 

Doug

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If you go to www.elliscustomknifeworks.com you will find a link to the person who bought the bussiness from them. I understand that he intends to offer everything that they did including horizontal and vertical forges as well as blown and venturi burners.

Hello. I'm that guy. I will be fabricating forges again in the near future. I'm also happy to help walk anyone through building their own.

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Nice to hear from you, Wayne. I hope to be able to do bussiness with you in the near future.

 

Doug

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Thanks so much for all the reply's from everyone, unfortunately the gas forge will have to go on hold for a while as I am being given a charcoal/coke forge for FREE, and that was just to good to turn down.

 

I have a few questions about this forge however I realize they will be hard to answer with out pics of the forge, however hopefully you can help.

 

The forge is blown from the side, and it appears to just be a basic metal box with out refractory, however this is rather large. should i coat the entire thing with some refractory, or would I be better off getting some fire bricks, and filling some of the space to make a sort of fire pot.

 

Also what fuel would you suggest for this type of forge? coke of charcoal?

 

my personal preference is charcoal as I move around with the Australian Navy so it may be hard to secure a supply of coke for it but I'm not sure if this is the best way to go.

 

p.s. For anyone wondering it was offered after I asked on the work classifieds about buying a gas forge :)

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By "rather large" (and here that Australian connection is kicking in...) do you mean about a meter per side, maybe 15-20cm deep, and with a big hollow cast iron tuyere coming in from the back?

 

If so, major score! Those were designed for coke, but will run charcoal just fine. I think a firebrick floor is all they need, but one of the English smiths (ahem-Owen!) who use them regularly may have some more input.

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hey alan i just managed to get the photos and exact dimensions home :)

 

overall size is 900H x 800W x 370D, the tray on top is 130H x 500W x 370D

 

Forge1.jpg

Forge2.jpg

Forge3.jpg

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COOL! B)

 

Sorry for the delay in response, things get away from me sometimes. :wacko:

 

I'd think a floor of thin firebrick and some clay lining would make that a very nice forge for charcoal. That uncooled tuyere wouldn't stand up to coke for long, and the single-action foot bellows (my favorite part of that forge!) would have a hard time keeping coke going.

 

Here's a link that might help withideas on how to fire that puppy up:

 

http://www.bladesmithsforum.com/index.php?showtopic=9873

 

Since the search function on this site is basically worthless, I suggest doing an advanced Google search for the exact phrase "side blast" on domain "forums.dfoggknives.com". You'll get a LOT of stuff that way.

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well I guess I'm coming hack with a guilty look on my face as its been fired up and I must say its good fun :) works a treat with charcoal so I'll keep with that however I do need to get some firebrick for the floor to help look after it, should I just put a single layer covering the whole floor for general use? or should I make some sort of shape to help contain my fire, as I noticed when using it that the fire tended to go everywhere as soon as I took the piece out.

 

time to go find someone who will sell me fire bricks :)

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Glad it works for you! :D

 

As for fire containment, some of the threads I saw mention using bricks to do so, some poeple use a sprinkler can of water. Clay will work instead of bricks too. It doesn't last well if you use a lot of water on the fire, though.

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