Portable side blast forge

[Broadus]

I've finally decided to level up from a break drum forge, and I want to do it right this time. I've been studying up, and I think I may have designed the forge I want.

I just want to check that I'm not overlooking any fatal errors in my design, which I know has flaws.

I would have used a tried and true premade design but I couldn't find one that had all of the features I want. Those features being; a compact, water cooled side blast forge with a hood which will function outside, this is a lot to ask for. Basically a do all forge I can take almost anywhere.  This would be much easier if I didn't also want it to look good. The main problem is to get the hood (super sucker because its the smallest that will function outdoors) and the bosh tank to fit in the same space. My solution to this is make the bosh a kind of U shape so that the hood can fit in the middle. I'm not even sure if this is even necessary because the bosh tank is now stupidly big (13 ish gallons according to the liquid volume calculator I used.) so I wonder if I could just get away with just a wide shallow bosh. The reason I wont just make a thin tall bosh (which is obviously most effective) is because I don't want the hood to hang off the back of the forge, I know its finicky but I want a really nice presentation when I take it to the fair, and because I'll have to look at it the whole time I work. So I'm trying to keep the bosh tank the same dimensions as the base of the hood. 

 

So does anyone see anything about this which won't work?

Thanks in advance, Broadus.

[Charles R. Stevens]

Er, I don't see a brake drum...

trim that "starter hood"

[Broadus]

Not upgrading a brake drum forge... upgrading away from a brake drum...

 

I quickly learned that brake drums don't really work as forges...

[MrDarkNebulah]

What are you using as the firepot?

[Charles R. Stevens]

A side blast forge typicaly dosnt use a fire pot, MDN. 

Just giving you a ration Bro, many smiths started with, and some still use brake drums. But I agree they are a PITA. 

What is your fuel of choice? If using coal or coke, how big a stock are you planning to work? 

I would move the hood forward, instead of rapping the bosh around it. 

32" square is probbabely a better base. Bosh hangs on the back, the hood sets on the backedge so the center of the fire is I front and in the center of the base. 

[Everything Mac]

Have you considered making the tue iron longer so you can put the chimney in front of the bosh? That seems easier than trying to fabricate a U shaped bosh to me. 

 

But of course that means a bigger overall foot print. - pros and cons. 

Looks to me as though you have done your research, the plan looks good. If you are able I'd fabricate the bosh out of stainless. Or consider getting it galvanised. Burning it won't be an issue as it will never get over 100 degrees.

 

Failing that I'd planned on painting mine with a cold galvanising paint called Galvifroid. Then I picked up a "proper" forge with a cast iron tue and bosh so the self build went out the window. 

 

Best of luck. I look forward to seeing it finished. 

Andy

[Broadus]

Charles I will probably be using bituminous, but if smoke becomes an issue with a crowd I'll probably use anthracite or charcoal, maybe Coke, I'm hopeful the hood will take care of that though. 

And I'll be mostly doing very small stuff with this forge, 1/4-1/2, though I'll probably push its limits setting up some tooling. 

I really don't want to push the hood out into the "bin", I think a hood places awkwardly can look really tacky (I'm going to be demonstrating at a a big festival with it, so presentation is important). I'm not worried about the added difficulty of fabricating the u shaped bosh, the guy who I'm going to have help me weld it up (since all I have is an arc welder and I'm rubish with it) has made motorcycle gas tanks. Though I may make a smaller bosh and make a bigger gap between the bosh and the bin.

thank you very much for your insight! I know you're one of the only side blast forge guys on this side of the pond. 

 

Mac I definitely won't be making it out of stainless! I'm too stingy for that. But I was going to make it out of a thicker sheet (11 gauge, or 1/8"). I'll have to look into galvanizing! Though my dad said he had some sort of gas tank liner stuff, "red coat" or something. I don't know how it's so with heat though. Small footprint comes first as this is going to be my mobile forge... I'm going to build a MUCH bigger one in my shop when I get everything cleaned out.

[turbo7]

It looks to me as if the bottom of the chimney is surrounded by the bosch? If that is the case wont this heat your cooling water? To a point where the water wont be doing any cooling at all. Why not just go with a sacrifical tuyere instead of a water-cooled one?

[Broadus]

I suppose it would heat the water more... Though I don't think it would heat it enough that it would stop cooling the tuyere, though I will make a small air gap between the hood and the bosh, possibly even fill the gap with refractory of some kind. Without the bosh the placement of the hood gets awfully awkward... Does anyone know if the super hood would work in a more upright position? 

[John B]

Just a couple of details, you have failed to show where the front of your tuyere is, this forms the basis of your fire centre, so you can move your chimney forward or, move the tuyere and bosh back a relative amount which would then allow you to have a rectangular tank as opposed to the U shaped one. (I am somewhat concerned about convection currents and water circulation if you go with the U shape).

Are you using hand cranked or electric motor for fan?

If you use coal or charcoal and a hand fan, you will not have to dissipate so much heat as you would using coke which you have to keep a constant air flow through.

You also include Super Sucker chimney, How high is this going to be? If you move the chimney forward over the fireball, then the heat will rise straight up , super suckers need height to draw efficiently, this may affect stability and pose mounting problems.

Nice theory, and drawing, I hope this is useful and helpful, you have put a lot of time and thought into this project, and I don't want to put a downer on it. The time to alter plans is before putting them into production.

Good luck and I look forward to seeing pictures of it finished and in action.

[Wayne]

If you are doing a portable forge, how portable?

I have an all metal portable forge that breaks down into base, hood, steel plate that sits in bottom of the hearth and takes a fabricated firepot and to the rear a set of double lunged pear shaped bellows.

The base is fixed with carrying handles on each side that double as tong racks.

A water cooled bosch is fine but you will have to source the water each time - 13 galls = approx 130lb so the base needs to be strong enough and you have to keep the tank topped up.

I am not sure if the chimney would be tall enough to provide any appreciable draw especially in the open air. The hood on my forge is less for smoke and more to provide a wind break - useful if using charcoal and to provide shade over the fire to judge the colours.

It closes the back  over hangs the entire hearth for the shade and wraps around about one third of the way to support the hood and provide more shelter. The top of the hood is a truncated pyramid in shape as a nod towards a chimney.

[Kozzy]

Still throwing out an "experimental" idea here--ceramic tuyere.  It has a low thermal conductivity and can be pretty tough stuff.  It's not your Grandma's crockery.  Maybe put a little refractory protection so you don't chip the end...but it'll definitely be about as tough as a metal tuyere at temp without some of the other problems.  

The benefit is that you should be able to eliminate water cooling altogether.  Cost for a 12" tube with a 5/8" bore (.875 O.D.) is about 60 bucks USD.  There are thicker walls available.

I just noticed coorstek has an online store that sells a ton of options retail  http://css.coorstek.com/scripts/css512.wsc/op/op_indexB2C.html#66453  (moderators, eliminate that if needed but the intention was to show the standard availability list, not "sell" stuff).  The Alumina says it's usable to 1700 C or 3092 f  I didn't look at the other ceramics for their ratings.

Is a hundred buck experiment worth trying before you do all the fabrication and fiddling involved with the water cooling?  Nothing says you can't go back and correct it if you don't have success.

[Broadus]

The height of the chimney illustrated is only that tall because I ran out of paper, I could make it much much heigher. I really dislike using Coke so I don't have to worry about designing it for that.

 

So if this overly complicated bosh won't work I'll just compromise and push the bosh back and the hood forwards... Before I start fabricating does anyone know if the super sucker would still work outside if it was oriented like in diagram B? 

I will be powering it with a hand crank blower, but I may build a pair of bellows for the sake of presentation. And I definitely won't be building a bottom blast, a side blast seems like a much better design, and it has "visual mass" where as a bottom blast is just a flaming table, once you add all your forge jewelry and du dads I've found it that the flaming table can become to look very messy and confusing, especially to someone who doesn't know what they're looking at. 

 

If the alternate hood orientation won't work I'll go with design A.

 

thanks for all the help! 

 

 

[Charles R. Stevens]

Disappearing posts?

Or is my coment to snarky?

[Broadus]

Disappearing posts I think? Charles I only see your two posts from yesterday 

[Charles R. Stevens]

Pm sent. 

Se dosnt look so bad, scorea (volcanic cinder rock) and ash would be a light fill 

[John B]

Your C design will work outside just fine, this one is at a show where the forge hearth has been brought in from a working forge, there is a very short chimney section which is in effect a register plate for a taller chimney when it goes back to the workshop. 

 

You could take your water tank further up to incorporate the hood support to help stiffen the canopy, this would mean you could have a narrower bosh with the same capacity as a smaller and wider one, a drain tap should also be incorporated if you are going to be using it at various events.

 

,

[Broadus]

I greatly prefer the look of that style of hood, but I was under the understanding that, that type of hood drew smoke based on the rising smoke just being funneled up. Though your forge does have quite a wind block...maybe that's the solution I need!

[John B]

It is rising heat that causes chimneys to draw, not the smoke.

One way to start any chimney to draw smoke away is to light a ball of newspaper or some small kindling and pre warm the chimney as you start to light your fire. Hot air rises and this helps to get the smoke (heavy air) to rise. The smoke will ignite when it is hot enough to, and will clear, whilst you work.

Once your fire is going there should be no smoke from it, its new fuel that smokes.

The picture does not accurately depict what you perceive as a wind block, there is a side screen as well as the hearth back, in effect forming an L shape and you work it from the open side depending on which way the prevailing wind is,  May be site dependent depending where crowd is looking at you from. This side screen can be detachable so you can choose to use it or not, it is not unknown for one to be hinged from the canopy itself, 

Edited May 6, 2016 by John B
Side screen details added

[Broadus]

I understood all of that, and I was calling the side screen a wind block. I've heard and seen that a big hood like that doesn't work outdoors, is it the side screen that makes yours work? Sorry if this sounds argumentative, I'm just making sure I get it right... That style of hood looks so much better and is much simpler to design around this style of forge.

[Latticino]

Side screens not only help with crosswinds, as you have noted, but significantly reduce the amount of airflow needed to go up a hood to capture any fumes generated from below it.  Has to do with edge effects and containment of plume.  Theoretically a hood with good side skirts, if close enough above the fire to capture the plume and having a nice gradual taper to the stack, should capture more heat and fumes than a side sucker with equivalent stack (though the latter work quite well also).

[Charles R. Stevens]

Nice to have a shady spot to judge steel temps, hoods are good that way

[Broadus]

Oh!! Well that's great! I I can go back to my original design! I was so bummed out when I found out I "had" to use a side draft hood outdoors! Thanks guys!

By any chance does anyone know any good plans for a real hood? If not I'll find/make some. 

[Frosty]

I only have one observation and bit of advise I'd like to offer. I don't burn solid fuels often but my experience has shown me a side draw hood clears smoke better than an overhead. That's just my experience.

My observation regards this thread is your concern with appearance. A professional looking kit is important to a good demo. However it doesn't matter how good it looks if it doesn't work well. Most people don't know what a "real" forge is supposed to look like but they don't like breathing smoke or getting showered with ash. They almost always like a sniff of coal smoke but not being engulfed by clouds of it.

That's all I have to add, worry more about how it works than looks. Form follows function is the moto of successful operations.

Frosty The Lucky.

[turbo7]

One thing that really helps a chimney draw is having larger area of pipe and smaller area of inlet. Hood and side screens will help outdoors especially when using charcoal.