Forge length

[fishfinder401]

Hi everyone, my apologies if this has been discussed before, i searched but couldn't find it.

So, my question is, I am planning on getting my first gas forge to let me heat treat a little longer of blades than my small kiln and coal forge will let me. my current limit seems to be about a 8in blade.

So, I am thinking of getting the diamond back 2 burner knife maker, the chamber is 13.5 in long, but how long of a blade could i theoretically get to temperature inside of it?

I was originally going to get 3 burner from majestic forge, but had heard some negative reviews of fuel consumption and quality so i may be steering away from them, unless someone else convinces me otherwise.

any tips on what size blade i should be able to harden in it?

Thanks

Noel

[Binesman]

First i would recomend reading up on the forge 101 pin.  Second i would recomend googling waynecoe artist blacksmith and reading the forge build plans on his site.

What im getting at is you can build a much better forge for what you want a lot cheaper.

As for what length you want it realy depends on how the forge is built and how well it holds heat.  My forge is 1 foot long and by sealing most of the front and back and carefully passing the blade through and allowing soaks as needed i was able to heat and quench a 26" blade (i could probably push it up to 36ish but 26 is the largest blade i have made)

[Charles R. Stevens]

Many knife makers have gone to vertical forges to minimize warping. 

What kind of coal forge do you have? It makes a difrence in how I can help you modify it to work. 

[fishfinder401]

4 minutes ago, Binesman said:

First i would recomend reading up on the forge 101 pin.  Second i would recomend googling waynecoe artist blacksmith and reading the forge build plans on his site.

What im getting at is you can build a much better forge for what you want a lot cheaper.

As for what length you want it realy depends on how the forge is built and how well it holds heat.  My forge is 1 foot long and by sealing most of the front and back and carefully passing the blade through and allowing soaks as needed i was able to heat and quench a 26" blade (i could probably push it up to 36ish but 26 is the largest blade i have made)

I will, thanks for the recommendation, and i would build one, but right now i think i would prefer to get one i know works, and get used to that first( i have never actually even seen a propane forge in person before) and the diamond back i am looking at  seems to be well insulated from what i have seen, but the fact you can heat a 26 blade from a foot long forge 

6 minutes ago, Charles R. Stevens said:

Many knife makers have gone to vertical forges to minimize warping. 

What kind of coal forge do you have? It makes a difrence in how I can help you modify it to work. 

that's interesting, when i do eventually make my own forge( which i plan to do eventually) ill give making it vertical some consideration

And i have an old riveters forge, and i have modified it with an extra air source from the side to add some length, which got it up to about 10in. 

[Charles R. Stevens]

What I would recomend is taking a page from the compleatly modern blacksmith and cut a piece of 2-3" pipe in half and lay it in the bottom of the pan, use some Adobe mud to seal things up. A few 1/2-3/4" holes spaced down the length will give you a 16" fire or so. Might have to build up the sides with mud to get enugh fuel depth. A bent piece of sheet metal even to help form a fernace . So now with a 16" 'trench fire you can move the blade back and forth and heat a 24" or more blade. 

Another option would be to build a strictly heat treating trench forge, somthing like a meneiture sword forge. 

Now gas is nice because when it's dialed in you can't burn up the steel but honestly as heat treat is the least time involved knife making task. 

[ThomasPowers]

I'd spend some time going to ABANA Affiliate meetings and learn about various propane forges before sinking that much money into one.

Very seldomly do you need to heat the entire blade all at once so if you buy a forge for heat treating expect to either buy another one for forging or waste a lot of money heating a forge that's too big for what you are doing.  (perhaps 4 to 5 heats for heat treating vs how many for forging???  Heating more than you can work results in decarburization, grain growth and scale losses.

[Charles R. Stevens]

On Thommas and Binesman's suggestions, I have seen it recommended building a good burner that can be taken from vertical heattreat fernace to horizontal forge. Personaly a PITA when one can build 2 T burners for cheep. 

As you already know from forging with your coal fire, you can only effectively forge 6" or so per heat, and as a knife maker who has read the knife class section, you know that unesisaraly heating steel can have undesirable effects in the steel. So for gas a small one burner and a long (vertical) one burner forge are suggested. Steve forges and forge welds in his coal forge. And I know for a fact their is a 34" longsword blade in his shop he forged and heattreated. I suspect he used the long gasser for heat treat but he has a long hearth and manifold available to convert his coal forge for such duty. 

For my self, I have a two burner proforge as my daily driver, being a farrier being able to heat 4 bars/shoes at a time is advantageous, and grain growth and Decatur aren't concernes, but unless I'm forging oxbow sturips I generally use coal and charcoal at home, and am seriusly considering building a coal forge for the truck.

 

[fishfinder401]

I am also planning on using it for making some Damascus so it would get more use than just the heat treating, and I plan on still using my coal forge as my main one for regular forging, because it heats just what i can forge which definitely has its benefits with not unnecessarily heating the steel like you said, just difficult with larger pieces, and its not the easiest for me to get coal, so the amount i found i burn when doing forge welding doesn't seem worth it when i can use propane for that that i have easy access to

I have considered making a trench forge, i just honestly don't have the room for that right now, still at my parents place, and pushing it as far as the space i am already using for my setup

so, as far as vertical forge go though, Have you seen anything on the Ellis 12 VT? or their horizontal 8 HT?

Also, I appreciate all the the advice, I have been pretty much completely self taught, so others opinions are greatly appreciated

[ThomasPowers]

WHAT!  So your basic plan is to buy a dump truck to haul large loads a few times a year; but you plan to use it for road racing too so it's ok?

[fishfinder401]

2 minutes ago, ThomasPowers said:

WHAT!  So your basic plan is to buy a dump truck to haul large loads a few times a year; but you plan to use it for road racing too so it's ok?

I don't really see how that analogy works with my situation...

[Charles R. Stevens]

A forge for patern welding billets is a very difrent forge than a forge for heat treating long blades. A billet welding forge being the rally car wile the sword forge is the dump truck. 

Getting a gasser to forgeing heat out of the box isn't easy. Most are not lined with divide see insulation or Ir reflecants. No rigidiser/hard facing and you risk lung damage and no IR reflectent you was't a bunch of fuel and may not reach welding heat with out excessive scale. So you spend $600 for $60 worth of parts and still spend $90 to make the forge right? Please read forges 101 and burners 100 in the gas forge section. I would rather you spend $200 on building two good gassers and $500 in materials.  

Thommas, I know Steve still welds bulite in his coal forge, are you using gas these days?

[fishfinder401]

2 minutes ago, Charles R. Stevens said:

A forge for patern welding billets is a very difrent forge than a forge for heat treating long blades. A billet welding forge being the rally car wile the sword forge is the dump truck. 

Getting a gasser to forgeing heat out of the box isn't easy. Most are not lined with divide see insulation or Ir reflecants. No rigidiser/hard facing and you risk lung damage and no IR reflectent you was't a bunch of fuel and may not reach welding heat with out excessive scale. So you spend $600 for $60 worth of parts and still spend $90 to make the forge right? Please read forges 101 and burners 100 in the gas forge section. I would rather you spend $200 on building two good gassers and $500 in materials.  

I am not looking for something specialized to do either amazingly, and i'm only looking at heat treating a 16-18 or so blade, not a sword. the forges i mentioned either do have the rigidizers and reflectants or use a ceramic insulating hardboard, not the kaowool that needs to be coated, and the forges i have been looking at also have been proven to easily get to forge welding temperatures.

I have done my research ( but i'm not pretending that i know more about it than someone who has extensively used them before), I wasn't looking for how to build the perfect forge or anything like that, I was just looking for some insight  in general on the relation of the how long of a blade i can get up to temperature for a given forge length( which i know can have a decent amount of variation depending on the forge), or if someone had opinions on the forges i mentioned

and i do realize that building a forge would be cheaper, but for me, at the moment i would rather spend some extra money now and be able to use it sooner, not spending my little freetime over the next few weeks trying to build something and having to experiment with it 

[ThomasPowers]

For forge welding a billet you usually want to get a small space MUCH hotter.  Heating a large space that hot is just tossing money into the fire.

Usually we get people here that claim to be budget constrained and then say things like: "I  can't afford to spend US$20 to buy proper forge insulation so I will use something cheap that won't work and spend $200 extra on fuel"  Well that's how I read it...you can see why I get perplexed.

Also billet welding tends to be hard on a forge; paying extra to buy and then heat excess space and then wear it out faster seems contraindicated to me as well.

[fishfinder401]

3 minutes ago, ThomasPowers said:

For forge welding a billet you usually want to get a small space MUCH hotter.  Heating a large space that hot is just tossing money into the fire.

Usually we get people here that claim to be budget constrained and then say things like: "I  can't afford to spend US$20 to buy proper forge insulation so I will use something cheap that won't work and spend $200 extra on fuel"  Well that's how I read it...you can see why I get perplexed.

Also billet welding tends to be hard on a forge; paying extra to buy and then heat excess space and then wear it out faster seems contraindicated to me as well.

that's why i was thinking a forge with an internal dimension of about 1ft would be a decent compromise, because from what i heard earlier in the thread it would be able to do the size blades i am looking at, but not be excessively big, and yeah, i have seen those kind of posts you are talking about where people arent willing to spend a little more upfront to save more money later on, i hope that isnt how i came across,  and that's not in the position i am in, i plan on being able to spend around 500, so i can get something that is decent out of the box( with either a coated or solid refractory material because realistically i only have a little time on the weekend to work on this stuff, and right now, i don't have enough time to put enough time aside to build a proper forge myself while doing the forging i need to ( i have a few knifes i need to make and finish before Christmas)

I should also mention that for me right now forging is mostly a hobey, so its not going to be used 8 hours a day everyday, or anywhere close to that( although i wish i could say it would be used that much

[Charles R. Stevens]

We so many new and ill informed smiths come here, as well as have so many folks either lurking now or in the future we ere on the side of cation. 

From oersonal experiance the soft brick or board liners tend to be sensitive to both flux, thermal cycling and physical damage. They still benifit from a coat of castable and a coat of IR reflecting coating. The same for rigidiser on Inso or kool wool. Borax eats it or you poke it either way, be prepared to coat/re coat. In my oppiniin a two burner is still waisting a lot of fuel for general forging and billet welding. Depending on where you are. Here I don't get a subsidy for buying LP or propaine like others in the world do.

Myself, at $160 a ton coal is a good option, or building a small gasser instead of my proforge. I might even desighn one I can flip on end and place an insulated body ontop for gental heating for heattreatment. 

Mike has found some soft (insulative) fire brick that seem to hold up beter so relineing a small share body might not be so bad these days.  

One foot square?! 144 square inches? How much much valume  dose the blade take up? Is this inside or out side? 

[fishfinder401]

Haha not one square foot, just one foot in length... One square foot would be l way to big haha. And why would 2 burners still be larger than needed? 

And I can understand you erring on the side of caution for those reasons

That is really good to know about coating even the solid insulation, what would you recommend?

And I wish coal was that inexpensive for me haha, I have to buy it in 60lb bags for about like 15 a bag I think, and the place is only open during work hours...

[Charles R. Stevens]

Mike and Jerry are the i house experts on gas forges, one should be along to chime in

[Binesman]

Fish the more i read the more i have to say you realy need to build your own forge.  Im still working atm but ill be off and home in anhour or so and will use the com instead of phone to give you the reasons.  8n the mean time you only need a single burner my 1' tube forge 10" OD 6" ID is only a single 3/4" burner 

[fishfinder401]

I agree that making my own would be ideal, but i just don't have the time right now, but who knows, ill see what you say, maybe it will convince me!

[Binesman]

okay fish here we go.  This will be long and drawn out.  Please understand that a lot of what I'm telling you I have learned from practical experience and observation.  Frosty/Wayne/Mikey all have forgotten more about this material than I will probably ever know.  So if one of them pops in and says something contradicting me LISTEN TO THEM.  Also i'm not a very sciency guy so some of this may be explained very simple (it is not done as any form of insult to you.  the problem is me not you)

Lets start with each piece of the forge.

ceramic fiber blanket/board.....these prevent heat from escaping.  they don't store heat or anything else they just stop it from running away.  Blanket MUST!!!!!!!! be ridgidized I can not stress this enough.  I have never used board.  I have been told by the furnace repair shop I purchase my blanket from (they have never used board either and thus this info is 3rd hand) that board presents just as much threat if it should be punctured/scraped and that it too should be ridgidized.  I can not confirm that information however if I where using it I would error on the side of caution and ridgidize it as well.  If flux touch's blanket/board it pretty much pulls a wicked witch and melts in seconds.

 

refractory....(personaly I use kastolite)  This traps the heat holds it inside and reflects it back in to the forge.  It also forms a nice protective layer over the blanket/board giving you safety beyond the ridgidizer.  Flux will eventualy tear up refractory (some more then others kastolite stands up to it fairly well) also giving your blanket/board protection from flux.  It is more thermal mass meaning it will hold the heat better allowing you to reach temperature and turn down the gas.

 

kiln wash....there's lots of different ones and lots of different reasons to use one.  they can make the forge heat faster/hotter/hold temp better/protection, that list can go on and on.  i'm going to talk to you about 2 ITC 100 (this is what is used on any production forge I've seen with a kiln wash).  ITC heats up FAST it will get your forge to temp in probably 1/2 the time as a forge without it.  It will let the forge get hotter I don't know how much so but if I where to guestimate i'd say 300F or so.  It does not provide any further protection in fact it seems to scrape off VERY easily and in my experience when flux hits it you can kiss it goodbye.  The next wash is Matrikote (this is what I use and I have not seen it used on any production forge).  Your forge will actualy heat slower (you have added thermal mass) the amount isn't that much when going up to the 2k range it takes me about a minute longer in a matrikote coated forge.  The forge will get hotter (performs just as well as ITC in this category).  It is more thermal mass meaning it will hold the heat better allowing you to reach temperature and turn down the gas.  It is a hard face (kind of like concrete) it doesn't come off very easy and it holds up to flux better than refractory.

 

So here's my "layers" of a forge.  irrigation pipe (shell),  2 layers of 1" blanket each ridgidized (2 layers for safety and ease of changeout if something manages to get far enough down to damage blanket).  This is what stops the heat from escaping.  Then 1/2" layer of kastolite 30 refractory This is what actualy holds the heat and transfers it to the material i'm working.  then a kilnwash of matrikote90ac see about for what this does.  

The end result is that whatever PSI I need to get the forge to the desired temp I can pretty much 1/2 once I reach temp (I have seen no production forge that will allow this)  The big benefit to this beyond saving money in fuel is it makes allowing material to soak MUCH easier.  this is a HUGE benefit when making blades.  Also when i'm forge welding I have both a kilnwash and a refractory hardface to protect my blanket.  I have never had to replace a blanket yet.  Matrikote is pretty easy to recoat mix with water and paint it on that's it. The few times my refractory has been damaged it has not been from flux it was from dropping material.  kastolite is just as easy to recoat mix with water and trowel on.

 

In the end for the things you want.  You NEED a refractory hardface and I would highly recommend a matrikote kiln wash.  Neither of these things will be in any production forge (maybe some of the industrial or VERY high end consumer but nothing your spending <500 on).

 

I understand the hesitance and the issue of time.  I will say when I build a forge the majority of the "time consuming" is building the burner and getting it dialed in.  What I would recommend then is build the forge body.  Wayne Coe sells all the mats you need other then a shell.  you can get a piece of irrigation pipe localy (every city has someplace that sells irrigation pipe) for like 20 the blanket/kastolite/matrikote will be <100 from wayne and that should give you leftovers.  That leaves you a 400 budget for a burner and a regulator/hose.  pickup a TREX they are very nice spend 1/2 a day building the body and have a forge that will work for what you want be efficient and LAST.

 

[Frosty]

Neither Diamond Back nor Majestic are rigidized or kiln washed. They use insulating board refractory which sheds smaller particles of the same stuff as a ceramic blanket. They're also vulnerable to flux erosion. Breathing hazards all. Rigidized, a hard flame face will make it MUCH safer and kiln washing improves efficiency for not that much outlay.

A little practice and you can heat a good length evenly in a 12" forge chamber for heat treat. Like any of the craft it's a little knowledge and a lot of practice. If you use a muffle you could heat treat a great sword in a rivet forge. Warpage would be a factor but if you keep rolling the pipe it should cancel out. Using a piece of moderately heavy wall pipe as a container for the blade and bringing the pipe to temperature it will heat the blade much more evenly and minimize decarb by keeping ambient air off it. 

This really isn't about the forge it's about how you use it.

That said I agree with buying something and getting to work rather than tinkering a home build. Some of us like tinkering as much or moree than beating hot steel. It's all good.

Frosty The Lucky.

[swedefiddle]

13 hours ago, ThomasPowers said:

WHAT!  So your basic plan is to buy a dump truck to haul large loads a few times a year; but you plan to use it for road racing too so it's ok?

Good Morning, Fish

The relevance is plain as day. You are setting criteria and you haven't started. Forget the Prince Valiant, start Forging and learning, start simple. Excaliber will come later, after you have learned how to burn Steel a bunch of times. Start with simple trinkets, work up to shives. Baseball doesn't go, 1st, 3rd, homerun. You start with T-Ball first!!

Neil

[CMS3900]

Hey Fish,

After reading what your trying to this is my opinion. Your trying to do three things at once: Billets, HT, and normal forging.  Each of these to be successful to a point need to be designed for the process. 

Billets: A vertical blown forge is king for this because you have less to worry about with flux destroying your forge as it drops harmlessly to the bottom which is usually filled with cat litter. Look at Bruce Bump, Jason Knight, ect.. and there using a vertical "Don Fogg" style forge. Some smiths like Ed Caffrey use a vertical that has a cast liner which is slower to heat but a lot more durable.  There are two very reputable turn-key vertical setups out there around your $500 price range.  PM me for links.

Normal Forging: Several bladesmiths have told me for normal forging all you need is a forge big enough to stick the work in. You could forge in a vertical forge as well.

Heat treating: If you only plan on using basic knife steels then a forge will do the job. Even a forge smaller than the blades length will work moving it back and forth. The coal forge with some techniques will allow you to use the same process to HT longer blades too.  However; anything that requires a specific soak time at a specific temperature is very tricky to do without a oven. For further consideration, the cost of a large HT oven or forge vs. the times you will need it might not make sense at this point. It might be worth the dollars to send large pieces out to be HT, which would open you up to use more than basic knife steels.

My suggestion would be get a good K type thermocouple (omega or similar), a long one that you could stick in your coal forge if need be, and a read out (amazon).

 

[Binesman]

6 hours ago, Frosty said:

Some of us like tinkering as much or moree than beating hot steel. It's all good.

Yeah im guilty of this and it may be clouding my opinion.  Just whatever tou do buy or build please make sure it is ridgidized.

[Frosty]

17 hours ago, Binesman said:

Yeah im guilty of this and it may be clouding my opinion.  Just whatever tou do buy or build please make sure it is ridgidized.

Exactly. Blacksmithing is inherently dangerous on many levels. Be smart and make it as safe as possible so you can do other dangerous things. . . carefully. If you're using ceramic blanket refractories use whatever methods necessary to separate it from the air. The first few forges I built were before I'd heard of rigidizers. The FIRST one was just a roll of kaowool with a chicken wire shell and my first functional T burner. Being a 1" burner in about 400 cu" forge it melted the kaowool before the steel came to temperature. There was so much dangerous about that set up it makes me shudder. I'm glad it didn't last more than about 5 minutes before melting.

I still have the second forge it has a 1" kaowool outer liner and a 3/4" Pyramid Super air set flame face inner liner. It in all stuffed in a 10" dia. steel pipe about 3/8" wall. It's very similar to what we read about guys building early on, incredibly over built where it doesn't need to be and under built where it needs the extra. 

After seeing what happened to my first forge the second one's kaowool was completely sealed in. I cast the Pyramid Super flame face liner between sono tubes with a 3/4" annulus. (space between the tubes) Once set and cured I wrapped it in one layer of 1" 8lb. Kaowool and used news paper and tape to compress it so it'd slide into the pipe. Then I painted the exposed Kaowool at the ends with thinned Pyramid Super and once dry I welded the ends on. I used a hole saw to drill the burner port and sealed it with thinned Pyramid Super. The Kaowool was sealed in but good.

I didn't do this for health reasons, I didn't have a clue what I was playing with. I did it that way to keep the flame off the blanket so I wouldn't have to buy more and replace it when it burned up.

Were I still making pipe forges I'd do it the same way but use 2 layers of Kaowool and Kast-O-Lite 30 as Pyramid Super hasn't been available for 30 years. 

There are some tricks BESIDES PPE! to minimize the hazard. Use a SHARP knife when cutting it and compress it tight. The fewer strokes you use the fewer particles are shed. The other trick I use it to wet it down so free particles don't drift.

Do NOT blow off with air or try vacuuming particles off! Take a cool shower to remove particles before turning up the temperature. Hot water opens your pores and allows crud to enter your skin.

Yeah, the shower is a bit of over kill but it can't hurt, might help.

Frosty The Lucky.