I Already Own a Coal Forge, Why Should I Switch to Gas?

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Dave Budd

Gold Trader
Staff member
Jan 8, 2006
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Dartmoor (Devon)
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I use both gas and coke forges (well, and proper old fashioned charcoal with bellows when teaching/demonstrating) and each has it's up side and down side.

Gas is the easiest to learn with because it is much more difficult to burn the metal during heating and because you can see what you are doing (it isn't buried!). Gas is also less dusty and you don't need a power supply if you use naturally aspirated burner. If you are making a production run of things, then you can safely have several pieces of metal heating up side by side as you cycle through them. BUT, Gas is noisier (stood next to a jet engine all day), much hotter to stand next to so you have to use tongs or a very long bar to hold on to. It also heats everything evenly, which can be great for even heats over a uniform surface/volume (such as a billet) but also means that if you need to heat the thicker section of say an axe head, then the thin edge will be losing metal in the form of scale fo ages as the lump gets warmed through. Also, you can only make whatever shapes and sizes of work as will physically fit through the door and into the forge chamber. So forget hooked blades like sickles, large axes, large scrolls, etc.

Coke is dusty, has clinkers to contend with and that you will need to learn fire control (which does come quite quickly). BUT, you can adjust the size of fire to suit the work and if the work is too big to heat then wiggle it around and it is fine. You can locally heat an area of just a couple of inches by adjusting where in the fire you stick the thicker section of metal. You can with practice have several irons in the fire, just put them into a warming area rather than a heating area in the fire and then relocate when needed. Coke forges are more durable as you can't so easily catch and destroy the lining. Flux if welding doesn't dissolve the lining as it does with gas forges. Because you can get things hot fast, you get less scaling and thus less material and carbon loss from the steel (though you can adjust a gas forge to help a little there too). My coke forges are much quieter, but that is down to the type of blower you have or where you stick it.

So, really, neither is BETTER but each has benefits to making tools. I've taught people to use both, either upon request so that they could see which they liked most before setting themselves up, or because the item/student would benefit from one type or the other. Normally I use coke to teach in the main workshop because people always prefer to forge with proper fire, but pattern welding I prefer to use gas and when I had a blind man on a course I used it then too.
 

VaughnT

Forager
Oct 23, 2013
159
21
Lost in South Carolina
Gas is available everywhere, doesn't smoke out the neighbors, and is generally cheaper to operate than coal. While a coal forge is truly wonderful and I miss mine every time I walk in to the smithy, I can't deny that my propane forge is really nice to have.

The downside to propane is that you can't shape the fire like you can with coal. If the piece is too big to fit in the forge, you have to build an entirely new forge to allow for the piece. And this is going to happen. Lots of folks say, "Oh, I'm just interested in making knives."... and they actually think that will happen. Nope. You'll start out making knives, then you'll see a really cool plant hanger or shelf bracket that you'd like to try duplicating. Happens every time without fail. The Fickle Finger of Fate!

Definitely suggest propane for folks that are just starting out. It makes life just a little bit easier, and that's a good thing when you're trying to learn the trade.
 

Seabass

Tenderfoot
May 2, 2012
92
0
Borders, Scotland
I have the use of ceramic chip forge and it's pretty useless compared to the coke forges I've used in the past and on courses. Hard to control the heat and to get a short heat as mentioned above. No use for large section materials which you could wack up heat quickly on a coke forge.

Lack of decent smell either!
 

spader

Full Member
Dec 19, 2009
917
0
Scotland
I was planning to make a little make-shift forge with a few bricks stacked making a wee heat chamber in the corner of the back garden, and then using an old vintage paraffin blow torch. Not sure if this will work.
 

Dave Budd

Gold Trader
Staff member
Jan 8, 2006
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www.davebudd.com
it's not very stable though, so you'll either be pumping it the whole time to maintain pressure and thus temperature, or it will get hot and then cool really quickly. Still, I've never tried to make a gas forge with anything but, well, gas! I've used most solid fuels that will burn (wood, charcoal, coal, coke, peat, poo and even nasty briquettes once) and have seen waste oil fuelled forges, but they are burning the oil vaporised (see the 'backyard foundry).
 

Everything Mac

Bushcrafter (boy, I've got a lot to say!)
Nov 30, 2009
3,106
76
32
Scotland
I can't see a parafin torch being very effective. Get yourself a weed burner and use that to get you going with a propane tank.

I can't add anything more to what has already been said. Both are nice for different reasons. I prefer solid fuel for general forging and gas for blades.

All the best
Andy
 

spader

Full Member
Dec 19, 2009
917
0
Scotland
Yep, paraffin blow torch was just an idea - trying to minimise smoke from the heat source in case next door neighbors might complain about their washings get smoky smell while drying in the gardens, and also minimise the cost as well, as I am a newbie. But I would still try it out as an experiment one day. I have a few old rusty files kicking about in the shed, which could be forged into utility blades.