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Making a homemade forge, does anyone have any reccomendations for a suitable blowtorch?

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RickJoW

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Hello Fellas

As stated im making a homemade forge ( old breadbin, refractory lined) and I wanted to know if anyone can suggest a suitable torch to heat it? This will be for knifemaking so ill need to get it pretty hot.

Cheers

Richard
 

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There are lots of instructions on how to make "gas forge venturi burners" or "gas forge burners" if you want to make one from scratch. There are also kits you can buy as well as complete burners. Good luck with your project.

Pete
 

--Tom--

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Amal make good burners for small forges, I use one in mine.
Sadly a lot of the information on how to put them together was an old forum that is now lost.
 

Yorkieguy

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If it’s a simple small forge, (google ‘coffee can forge’, ‘paint can forge’) most use a mixture of plaster of Paris and sand for the refractory, and a standard propane blowtorch. (MAPP gas achieves a higher temperature and can be used with propane torches).

Good luck with the project.
 

--Tom--

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Here are two threads where Tim Gunn goes into some details:


 

Illy

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I made my own but whilst it worked, it just showed up its own limitations and I quickly got frustrated with it. I would recommend a Devil Forge (available online). Not expensive and perfect for knife making. There are lots of positive reviews out there. All you need to add is a gas bottle.
 

RickJoW

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Well, I failed. I got a Bernszomatic TS4000T and tried to use it for my hardening. It got nowhere near the red glow necessary to get the blade up to temperature.


Heres a shot of my set- up so if anyone has any suggestions they would be most welcome. This torch nozzle cost me seventy pounds and as far as i can see it just wont do the job. I was using MAPP gas which state it will go to 2400°C (and the nozzle is rated for that) but far as i can tell its next to useless for this.
 

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--Tom--

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That’s a lot of volume to be heating with a torch, how big was the knife?

Do you have a back and a way of closing down the front?
 

RickJoW

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The knife blade is about nine inches Tom.

Of course I can close the front. I'm using firebricks. I don't have back opening, but I could. Seems to me though since the attempt at heat treat went so appallingly bad that would reduce the heat accumulation even more.

I just don't think the torch is up to it despite being rated to be.

Before I gave up I tried heating just my pieces raw without the oven using direct torch heat. Still wouldn't get to temp.

In this instance I wasn't yet HT'ing my blade. It was two small pieces I'd drilled for a file guide. Thinking of using charcoal now.
 

Fergie 307

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You need a seriously larger burner. Like I say try the big burners roofers use. You could probably hire or borrow one first to make sure it does what you want.
 

Fergie 307

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There are loads of forge burners on E Bay, from about 30 quid. Best bet for your small forge. My idea of the roofers burner works well but only used it in something about twice the size of yours, might be a bit OTT.
 

Illy

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Well, I failed. I got a Bernszomatic TS4000T and tried to use it for my hardening. It got nowhere near the red glow necessary to get the blade up to temperature.


Heres a shot of my set- up so if anyone has any suggestions they would be most welcome. This torch nozzle cost me seventy pounds and as far as i can see it just wont do the job. I was using MAPP gas which state it will go to 2400°C (and the nozzle is rated for that) but far as i can tell its next to useless for this.
That was my experience with a blow torch fired home made forge. I did get it to temperature but it wasn't even everywhere alongth the length so I would have ended up with areas not hardened. So it went in the bin and I bought a small Devil Forge instead.
 

Terrytpot

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Well, I failed. I got a Bernszomatic TS4000T and tried to use it for my hardening. It got nowhere near the red glow necessary to get the blade up to temperature.


Heres a shot of my set- up so if anyone has any suggestions they would be most welcome. This torch nozzle cost me seventy pounds and as far as i can see it just wont do the job. I was using MAPP gas which state it will go to 2400°C (and the nozzle is rated for that) but far as i can tell its next to useless for this.
I’m spitballing here but would imagine the problem you have here is one of not enough air to fuel ratio. I made a small Venturi type of cylinder for starting off my barbecue which is fairly tame but when I “squirt “ the base of it with air from my compressor it soon livens things up 😉
 

novocaine

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1. you need oxygen, preferable in the form of air. right now you are choking the flame which will reduce it's heat output, it is drawing air through the burner already, but not enough to sustain a very hot flame, a fire needs fuel and air to burn hot. try a low pressure air feed around the burner air inlet to increase the pressure slightly, don't go to made as it will snuff the flame if you get away from the right mix.
2. If your torch is that way up, you are also spitting liquid down the torch that will cool the flame considerable.
3. you need a considerable smaller chamber for a torch that size, think 2" square and just long enough for the blade rather than 4" square and to long for the blade. you can use a few fire bricks in what you have to make it smaller.
 

chaoticbob

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The knife blade is about nine inches Tom.

Of course I can close the front. I'm using firebricks. I don't have back opening, but I could. Seems to me though since the attempt at heat treat went so appallingly bad that would reduce the heat accumulation even more.

I just don't think the torch is up to it despite being rated to be.

Before I gave up I tried heating just my pieces raw without the oven using direct torch heat. Still wouldn't get to temp.

In this instance I wasn't yet HT'ing my blade. It was two small pieces I'd drilled for a file guide. Thinking of using charcoal now.
Rick, when you say the torch isn't up to it 'despite being rated to be' I wonder if you are talking about temperature or power - elsewhere you say the the Bernzomatic torch is good for 2400 C, which makes me think perhaps temperature is what you're going by. But it's power that is more important in this application - which is why others have recommended a bigger torch. Your torch is rated at around 1.9kW max power, which is just too puny to get the heat into the refractory.

I use a Sievert 7.7kW torch with a standard propane bottle for this sort of thing - Gas Products do a kit for under £70. Once you've got the handle, regulator and neck tube, burners going up to over 40kW, if you need them, are relatively cheap.

You don't say what refractory you are using, but that's important too - solid fire clay bricks soak up heat and take ages to get to temperature. I have used a home brew refractory using clay and vermiculite with good results, but now just use commercial vermiculite slabs (the type of thing used for lining wood stoves). It would be no problem getting a 9" blade up to HT temperature with this arrangement and the Sievert torch.

It's not surprising that you couldn't get your pieces up to temperature using direct heat from your torch - it's just not powerful enough.

Charcoal can work for sure, but it has its own problems, not least controlling the temperature - which is important for heat treatment.

Bob.
 

Brian18741

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I used a super simple "2 brick forge" and a map gas blowtorch for a good while before getting my forge. Works great for heat treating etc but I wouldn't want to be heating metals to forge for a long period on it,would get very expensive very quickly!
 

johnnyb

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years ago I made an awesome gas forge using a t.rex burner and a gas bottle with a blanket type refractory painted with some stuff. the burner was incredible seriously hot. I sold it on ebay to a lads mum who wanted to be a blacksmith. a religious guy called rex makes them in the US. they were simple enough but being a venturi burner they need to be tuned not unlike a ported cylinder head!
 
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