Forge project

[Wendelspanswick]

Thanks very much for the offer but it a little far for me to travel and probably awkward to transport. Also the build is half the fun.

I am struggling to decide witch is better bottom draft or side draft. What are the pros and cons with either.

I have used both, all 8 forges in the Guilds workshop at Cannington were water cooled back draught but the portable forges were dry bottom draft. These dry forges were used for shows and roped in as extra forges during competitions.

The problem we found with the bottom draft forges is the clinker* sinks to the bottom where bits of it are constantly being blown back up on to the workpiece, unless you wire brush the workpiece constantly it ends up with a blemished finish. The clinker tended to block the perforated bottom plate as well.

With a back draught forge the clinker sinks below the level of the fire, the workpiece needs a lot less brushing and results in a more blemish free finish.

As apprentices we used to hate using the portable forges and during competitions where apprentices from all over the country would come to the Guild forge us 'local' apprentices would bag the permanent forges knowing that the visiting apprentices would get the portable forges. Home advantage every time!


Clinker, a red hot sticky mass that forms at the base of the fire when forging and is normally removed at the end of the day when it has cooled into a solid mass. The clinker is a mixture of all the impurities from the coke and the scale that falls of the workpiece, it's like red hot toffee and is a bugger to remove if it cools on a workpiece as it is as hard as glass and sticks like s**t to a blanket!

 

[dan.taylor.1]

Agree about clinker, but with careful design it can be got round, my forge has clinkers every time I use it but they never stick to the work or block the air.

Dan

 

[blacksmithstris]

I have a bottom blast forge and if I'm working it all day, the clinker needs removing half way through day and at the end of the day. Don't really see it as that much of an issue, hook it out and keep working, tends to come out in one big clump anyway. You can avoid that 'shower of lava' and the fire spewing out, blowing the clinker back up by not blasting the air abruptly when you know that there's likely to be clinker collecting at the bottom. Suppose you just need to managing the airflow and clean out the fire more often with a bottom blast.

I also have a gas forge and love that too.

 

[julianthegypsy]

Having used both, clinker is easier to clean from a side blast, but its never really been a problem on my bottom blast. I just turn the fan off for a minute and hook it out like a doughnut. At the end of the day I leave it and dig it out in the morning. Don't try digging it out hot, as someone already said, it's like semi liquid toffee

 

[Spark plug]

Ok so for the DIY use I will give a forge it appears it won't particularly matter weather I go for a bottom draft or back draft.

So I'm thinking Ile build it around the material I have available.

I have plenty 8mm plate witch I could use would this be too thin for a bottom draft as most people seem to use around 12mm for the fire pot.

What would be a useful size I'm not sure what I could end up making with it I have been planing on something like 600x1000mm, and what would be a good depth?

 

[blacksmithstris]

I have some plans for a bottom blast forge from the Blacksmiths Guild if you would like them?

 

[Spark plug]

I have some plans for a bottom blast forge from the Blacksmiths Guild if you would like them?

That would be very help full.

 

[blacksmithstris]

plans sent

 

[Windy Miller]

I have some plans for a bottom blast forge from the Blacksmiths Guild if you would like them?

Ay chance I could have a copy of those plans too please? I need to upgrade from my brake drum forge!

 

[blacksmithstris]

pm me your email address and I'll send them along, anyone else who wants them are welcome to do the same.

 

[Spark plug]

plans sent

Received, very much appreciated.

 

[steve.h]

I used a coke/coal forge for a couple of years, it is nice to work with a fire as it gives a feeling of a lik with the past. The op saying about cost of fuel with a gas forge, I dont think a gas forge costs much more than a cke forge to run, less time to heat up, no loss of fuel during cooling down. a lot of time is saved during firing of the gas forge as there is no "tending the fire" so more of your time is given to working the hot metal.
One of the biggest draws to the gas forge for me is neighbours, once a coke forge is running it is reasonably clean but still has the smell of coke, during lighting I have always struggled with lots of smoke. the gas forge doesnt suffer with smoke or smell, so now all I have to worry about it the noise of hammering the hot metal, although I have a couple of large magnets and a chain around the base of the anvil and the anvil is sat on a wooden block so a lot of the noise is deadened by these factors.
A gas forge doesnt need the same space as a coke forge with the area around for coke etc, I dont like the drum forges as its all too small. the other good thing about a gas forge is less cleaning of the workpiece, so time saved again. there is only a need for a 6" extractor rather than a chimney if working in a workshop...
HTH.
Steve.

 

[julianthegypsy]

Ok so for the DIY use I will give a forge it appears it won't particularly matter weather I go for a bottom draft or back draft.

So I'm thinking Ile build it around the material I have available.

I have plenty 8mm plate witch I could use would this be too thin for a bottom draft as most people seem to use around 12mm for the fire pot.

What would be a useful size I'm not sure what I could end up making with it I have been planing on something like 600x1000mm, and what would be a good depth?

8mm would be plenty thick enough for a bottom draft, but you wouldn't need to make the whole thing out of it. Make a plate about 200mm square and drill your blast holes in it, then build the rest out of two mil and bolt it in. In the unlikely event that it ever wears out you can just replace the plate for a couple of quid.

 

[Spark plug]

Ok Ive managed to get a few jobs done, so the forge is back on the cards.

In the meantime I have had the opera unity to speak to two retired blacksmiths. They have recommended me to build a rear draft forge, so I've picked up a sheet of 3mm to make the fire pot.

They also told me to line the fire pit with fire pot with fire brick to concentrate the heat within the fire.

I'm haveing problems locating fire bricks at a reasonable price, as I worked out I need 50-60 (depending on size).

Can anyone point me in the right direction?

 

[steve.h]

I used a bottom blower type forge, I lined the fire pot with castable refractory as the heat was making the 4 mm fire pot side white hot and soft. I used one of the 4 inch fans (they large fan type as you find in grow shops). the forge on a med air flow would burn 1.2 inch bar in under 2 minutes, it was really good, my problem is neighbours that live very close, once the forge was running it was fine but it smoked the whole street out while starting up.
I am now in the process of building a gas forge. I understand what the OP says about wasting gas, this might be the case but the forge will be up and running in less time, you have more control over the forge, you can have one piece of metal heating while working another, you dont have to spend 30-40% of your time looking after the fire and so your time working with the forge is a lot more productive.
The cost of running a coke forge overall is about the same as the gas forge, but as I say your energy goes into the work piece rather than tending the fire.

 

[steve.h]

Castree kilns are a good scource of firebricks, castable refractory and all the other bits you might need...

 

[Wendelspanswick]

I never bother with firebricks, if you make the forge big enough the unburnt coke, ash and coke dust will insulate the steel from the heat.
When I started my forge for the first time, 900mm square x 350mm deep or thereabouts, I filled it with new coke and dampened it down around the outside. Once you have used it a few times the ash and dust from the first fires collect round the outside of the fire pit insulating the unburnt coke from the heat.
If you want a small fire pit you push the ash in, bigger and you pull the ash out towards the edge.
It also means you can shape the fire to some degree, a long fire is good for heating long lengths for twisting or corn ears etc.
Having the forge full of coke means you can just drag in fresh fuel when needed.
The beauty of coke is as soon as you shut the draught off the coke goes out unless you jam a lump of wood in the fire.

 

[Spark plug]

View media item 7963
Well I finaly made a start today after getting sum fire bricks to work dimensions out so I don't have to cut the bricks.

Up to now I have the base and 3 sides cut and tacked together for the fire pit, with sum stiffeners tacked under the base to stop it sagging.

 

[Maker]

I cut a butane tank in half, drilled a hole in the side for a tueyre of 2mm tubing and a hair-dryer. I never used it as a forge because the smoke would annoy the neighbours apparently but I lit it on bonfire night, tried to melt a piece of aluminium in it and then suddenly it went really bright and melted the end of my tueyre into nothing. I can only imagine the rusty forge (iron oxide) and aluminium caused a Goldschmidt reaction (AKA thermite). Be careful with rusty metal + alu.

Yours looks really good so far.

 

[captain-destructo]

I cut a butane tank in half, drilled a hole in the side for a tueyre of 2mm tubing and a hair-dryer. I never used it as a forge because the smoke would annoy the neighbours apparently but I lit it on bonfire night, tried to melt a piece of aluminium in it and then suddenly it went really bright and melted the end of my tueyre into nothing. I can only imagine the rusty forge (iron oxide) and aluminium caused a Goldschmidt reaction (AKA thermite). Be careful with rusty metal + alu.

Yours looks really good so far.

or possibly magnesium alloy?

(i think thats how you spell it)