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Brake Drum Forge, Smokestack Question


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Hi everyone,

This is my first post so I'll introduce myself; my name's Jared from Montana, USA. I'm technically finishing my second forge now, a barbecue grill/brake drum combo charcoal burner (the first forge years ago never worked out).

Anyhow, last night I lit the forge up for the first time and it definitely got hot! The only problem I had was the mass of smoke and sparks that flew everywhere even on the lowest blower (hairdryer) setting. I live in a tight packed residential area (no noise or nuisance codes, thank goodness for me), and I'd rather not risk burning someone's house down especially when summer comes around.

I've been reading around here since last night about how to make a chimney flue to pull those wild sparks and clouds of smoke away from me and nearby flammables. Unfortunately, many of the threads are old and picture links are broken. All I know so far is that everyone recommends at least 10" dia pipe, and some places mention a shelf inside the pipe that stimulates the draft. Besides this I know really absolutely nothing.

I'm on a shoestring budget right now, and don't have a welder (or know how to use one). So, I'm attaching pics of what I have so far and reaching out to people more knowledgeable than myself for advice on how to install a working flue pipe to a charcoal grill with standard tools.

What i'm pondering so far is making a pipe like those you see on some Traeger pellet grills on the side of the body (pic attached). Maybe create some kind of metal box next to the brake drum that still fits under the lid, which connects to a pipe that goes out the side of the grill body below the lid line? Would this have any hope of creating a draft? This forge is meant to be portable from the garage to outside, so the pipe can't be too massive...

Thanks!

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Hi Jared, welcome to IFI. From the picture I see a problem. The hair dryer is supplying way too much air for charcoal even on low setting. Before you try & build a hood and stack, you need to find a way to bleed off a lot of the air. There are several threads dealing with making air control for charcoal forges.

Read through this thread for starters.

https://www.iforgeiron.com/topic/30887-forges-and-fires/

 

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Hey thanks guys,

 

Someone in that recommended thread mentioned a kind of current dampener to limit weaken the flow from the hair dryer. Is that a good place to start?

I had no idea until today that the forge design I chose was ideal for coal rather than charcoal. I'm not interested in coal personally, making this thing out of a grill is already non-traditional enough for me (I'm a history nut). Right now I'm about out of investment money to add much more piping to this thing until I get some paychecks, but I can see converting this into a side-blast someday as long as the current bottom-blast design with weaker airflow is at least workable for now....which I hope it is.

 

Did anyone have thoughts or ideas of how to incorporate a smokestack of some kind?

Also, ideally once I get everything going, about how full of charcoal should I fill the drum when I'm ready to heat steel?

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To make charcoal you remove most of the volatiles from the wood. The charcoal therefore smokes very little. The sparks are a product of too much air. Separate the dryer from the air pipe with a 3 inch air gap. Aim the dryer toward the air pipe for more air, and not so much toward the air pipe for less air to the forge. 

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12 hours ago, Stahlmann said:

 I can see converting this into a side-blast someday as long as the current bottom-blast design with weaker airflow is at least workable for now....which I hope it is.

It would require little to no extra money to convert what  you have to a JABOD style forge, assuming the legs and wheels on the grill can handle the weight.

https://www.iforgeiron.com/topic/44842-just-a-box-of-dirt-or-a-simple-side-blast-forge/

 

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You can fill the area around the brake drum with cheap unscented kitty litter mixed with sand then wet down to make bentonite clay.  Here is a thread about hair dryer for blowers. The post by Charles is the best for getting air to the forge without electricity. Before I started using coal I used lump hardwood charcoal (not bbq briquets) with my hand cranked Champion blower and one turn on the crank would supply plenty of air.

https://www.iforgeiron.com/topic/54044-hair-dyer-blower/

 

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Lots of ways to skin this cat, if you had done a bit more research the $60 you have tied up in pipe and blower could have been cut to less than $20 in efferent side blast . With the set up you have, you need to bring the drum up to nearly the height of the rim of the Grill, fill can be dirt, sand, gravel, lava rock, cat litter or any thing that the hot drum will not burn. Another option as mentioned is to drill a hole in the side 4-5” below the rim and install a length of 3/4” schedule 40 pipe for a tuyere. A $10 double acting air bed pump provides air and soil fills the grill with dirt, and either a dirt bank or some brick to work with. If weight is an issue 1/3 clay and 2/3 expanded mica is light 

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Great info and links guys, thanks!

That JABOD style forge looks like a great idea! I think I can get mine similar with the grill setup. I have a couple bags of perlite I can fill the bottom with to keep the weight low, then add a sand/cat litter mix above it up to around the top of the drum. Or does it work better to mix the perlite in with the sand/clay? If I ever needed to remove the clay to make the forge even more portable, I think keeping the perlite by itself would allow me to reuse it and save money rather than throw it away with the heavy clay. Just an idea.

On 2/27/2018 at 5:22 PM, Charles R. Stevens said:

With the set up you have, you need to bring the drum up to nearly the height of the rim of the Grill, fill can be dirt, sand, gravel, lava rock, cat litter or any thing that the hot drum will not burn. Another option as mentioned is to drill a hole in the side 4-5” below the rim and install a length of 3/4” schedule 40 pipe for a tuyere. 

Am I understanding correctly that I should put insulation/fill material under the brake drum to raise it to the grill's edge? If so, is there a reason I can't just fill the area around the drum to at or slightly above the drum edge? How many inches of charcoal, minimum and maximum, should I have sitting above the tuyere (both horizontal and verticle forms)?

 

I'm considering keeping the piping below the fire pot so that it can still act as an ash dump, and if necessary in the future be used as a bottom blast for coal. Good idea?

My interest is in making knives mostly, and so for longer blades would it work to make a furrow in the clay above the top edge of the drum so that longer blades can still lay horizontal? Would that make the fire pot too deep? I'd like to keep the drum in there so I don't have to destroy pretty much everything I've already done, and so it can work as an ash dump and potential coal forge, but is the brake drum pretty much mostly in the way at this point?

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Non flamible material, I only mentioned expanded mica if weight was an issue, insulation isn’t necessary. But to heat the center of a bar reaching down into the grill to reach the fire is a problem. 

With a side blast and a 3/4” schedule 40 tuyere (7/8” ID) one would be looking at 4” or so from the top of the tuyere to the top of the hearth, with some 2-3” of fuel over the work. If you look at the illustrations from the pinned article you will see a bank or bellows stone to pile fuel against. A charcoal fire with a the described tuyere produces about a 8” hotspot, I find a trench some 8x4” strait on the long sides and sloped from the bottom up. Works well and is easy on fuel. 

As to a bottom blast needs a deeper fire for charcoal, some 6-7” or so, any deeper simply wastes fuel so not moving the drum (fire bowl up isn’t a real option

 

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9 hours ago, Stahlmann said:

but is the brake drum pretty much mostly in the way at this point?

In general, yes.  If you were going with side blast then for sure it's just in the way.  If you want to supply air from the bottom it changes things a little.  The drum you have is still way bigger than you need for a fire pot, and as Charles pointed out you will have a hard time getting your stock in the right part of the fire with the current drum location.  A smaller drum, or better yet, a brake rotor will provide a more reasonably sized fire pot.  However, you will still need to raise the fire pot up close to level with the top edge of the grill in order to make it reasonable to work with. That could be accomplished by using fill material of course, but you still have to attach your air supply/ash dump piping to the pot, which usually means bolting on an adapter plate of some kind.  Getting good welds to drums or rotors is usually beyond the capabilities of hobby weldors with cheap welders.

If you go with a side blast all you have to do is create one hole in the side to introduce your air supply, fill your grill, and shape the bowl.  If you don't like it then you just remove the dirt/clay and try again.

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