Help with bituminous coal forge fire maintenance

[ZBarrett]

I know this is a very newbie question, but I feel that I'm not very efficient with my coal.  I've done some reading and have watched some youtube videos and I kind of know in theory how to manage my fire, but I'm not getting a consistent heat, or i'm smothering the fire when packing it down, or there are big clumps of coke that crust the top, heck sometimes I end up with a hole right above the clinker breaker.  I just want to be efficient and not waste time/fuel. How do I know if I have too much air or not enough.  I guess I'm just trying to get the "coal fire management for dummies" explanation on this.

[ThomasPowers]

It depends a lot on the coal you are using, the type of forge and blower you are using and what type of fire you need for what you are trying to do.

For example: using a nice coking sewell seam coal, in nut size, in a bottom blast, good sized cast iron firepot, for welding up billets, using a cave fire aka closed fire:  You want the nice solid cap; but don't want an empty area right above the clinker breaker. So once your fire is going good and you start adding more coal to maintain it you will take your Slice and near the edges of your fire shove it down towards the tuyere, shoving coked coal down into the hollow leaving the cap in place. Then add more coal to the low areas to coke up and a bit more on the cap to maintain it as it burns from below.

Using the same; but for an open fire for general work, break up the coke with the fire poker as needed to make it easy to insert the workpiece. Raking coke chunks from the edges as needed and adding coal to the edges to coke.

Blast control has so many variables that I'll say: use enough for what you are doing and not too much!

Best advice I can give you is to find someone close to you using the same sort of equipment and coal and see how they do it.

[ZBarrett]

Hey Thomas thanks for the reply.  The coal I buy I'm told as per the website is bituminous blacksmiths coal from Virginia (pea size from the looks of it).  I made my forge, it's 1/2" mild plate, that's  9"x10"x4.5"  I use a 70 cfm bathroom fan as a blower bottom blast.   I have spoken to a local smith about doing grunt work around the shop so I can observe, I just need to wait for businesses to open and book time off  (shhhhh don't tell the wife this is how I want to spend my vacation lol) and who knows how long that could be in here in Ontario.  Here are the pics of my forge and blower.  Yes I know the welds are ugly, I'm teaching myself to weld still.  I'm doing just basic work, I'm wanting to be proficient  with the basic skills before getting onto forge welding. (no matter how badly I want to make damascus)

 

[ThomasPowers]

So don't be afraid to disrupt large chunks of coke so they filter down in the fire better.  I often slap them with the slice or fire poker. 

Do you have a foot switch that turns off the blower when you leave the forge for the anvil?  It helps cut fuel consumption when you are getting started.

[ZBarrett]

I usually just close the air gate. I have a light switch that can turn it on and off,  I was just told that was very hard on the fan and to use the air gate instead.

[Frosty]

When you pack the fire, don't pack it too hard you can stop air flow if you over do it.

Frosty The Lucky. 

[anvil]

Here's basic fire control.

You need ~4" of coke underneath your work and ~2" of coke on top. This will create what's called a neutral to reducing fire.  This means the 4" below has consumed the oxygen before it reaches your work. The 2" on top does the same from oxygen coming in from the top.You need to maintain this. Keep your "green coal around the perimeter and keep it wet. The green coal will make more coke and your type of coal should make a good coke ring around your fire pot. When you notice that hole above your clinker ball you have what's called a hollow fire. Take your poker, which you should have already made, and gently break up your coke ring and fill the hollow space and make sure to maintain the 2" topside as well. At first you will prolly do this and get a mix of coke and green coal in the hollow. The green coal will make smoke. It will also create a "dirty" fire. With practice you will learn to keep the green coal out of your fire. You only want coke around your work. So it's important to work towards getting no green coal into your actual fire, keeping 4" below your work, and 2" above and the hollow gone.

Have fun.

[ThomasPowers]

Some of the good coal types don't need to be wetted down.  All the ones I've tried out west in the USA have needed it.

[ZBarrett]

Thanks guys this has been very helpful.  I do keep my coal wet in a bucket, and use a sprinkling can to keep things moist as per the back yard blacksmith, great book by the way.  I now have a better idea of what to do once I have the cap made,  I also believe I might of been packing things down too hard. Now hopefully I can get out and do some leaves and hooks....once I can get a baby sitter or school is opened....I hate this isolating thing......sorry about the small rant.

[ThomasPowers]

Almost worse is that I am stuck going to work everyday while a lot of smiths I know are going wild in their smithies in the spring weather.

[ZBarrett]

I hear ya Thomas.  I am working but only two days a week (service tech) and teaching my son his school work which is a full time job on it's own.  By the time I get free time I'm exhausted.

Going through the forums is great but I do get jealous seeing all the things everyone is making. 

[Donal Harris]

On 5/4/2020 at 1:49 PM, ThomasPowers said:

you will take your Slice

Pardon the newb question, but what the heck is a “slice”?

[anvil]

 I wet all my coal. The water is used to control my fire size from long and narrow to as broad as my fire pot will allow.. It keeps hot gases going where I want, and aids in the coking process.

Lol, I've used coal from good ole back east pochantus to Carbondale and all the rest of the western coals.

If I'm burning coke, I don't use water. I control my fire size much differently when using coke.

[Irondragon Forge ClayWorks]

A slice is a fire tending tool, similar to a spatula used in cooking. Here is a video showing how simple it is to make. Can be used for chopping up large chunks of coal or charcoal and moving the fuel around.

 

[Donal Harris]

It is restricted. Says I must have something called a G Suite account?  But I was able to view it buy searching in YouTube itself.  
 

I’ve always thought that thing was a shovel, because that is what people I’ve seen using it appeared to be doing.  I usually just use either my rake or poker to move coal or coke around.
 

It looks easy to make one and did a much better job than my primitive looking rake. (My rake looks something like the thing they use in casinos to rake in dice.)  And having seen his video, I will drill my holes to fit the rods I have available instead of drilling a hole and then trying to forge the rods to fit the hole.  

 

[bluerooster]

I find that I'm constantly poking the fire. Either to fill a void, or poke out a clinker, or add coke, or something.   My fire pot is kinda shallow at only 4", and as a result I build the fire kinda mounded above so I get close to 6" of hot coke.  about 2" of coking coal, and about 3" of wet coal.  I usually have quite a mound of coal/coke, with a hole in the top to allow it to breathe.  I have been known to pack it down too tight for air to flow. (oops) But I'll poke around and loosen it up a bit.   I don't really mind the "coke cave" as it seems to help hold in the heat. But it gets busted up eventually.    I try to feed the fire from the sides, and not from the top.  Pushing the coke into the pot, and sliding coal over it to coke up. But inevitably I get a little green in there too.  Not much but enough to smoke some.   But it's usually on top of the coke, not down in the pot.

After about an hour or so, everything that I've loaded into the forge for that session, has pretty much coked up, and I get very little green going into the fire from then on. But there is some, from time to time.

  For my forge, it requires constant tending.  But it works for me.

[anvil]

Sounds like you have a good grasp of fire management. The routine doesn't change, it just gets more habit.

I don't make a "coke cave", I just make sure I have ~2" of coke on top.

Your fire pot depth is fine. ~4" of coke underneath your work is sufficient.

" I usually have quite a mound of coal/coke, with a hole in the top to allow it to breathe".

Always keep your coal and coke separate. Green coal makes smoke and is considered what makes a "dirty" fire.