multi-port side-blast charcoal forge design, input requested.

[Javan C.R. Dempsey]

Hey guys. I'm finally getting around to building a new charcoal forge, I've been planning on for a while, but I'm hoping for some input on some design concerns that have manifested in my brain since I finally got the components together.

I'm building a linear, rectangular forge, with a roughly 18"x6" wide firepot. Its going to be hard firebrick floor, with 2" ceramic fiber walls coated in castable refractory. The whole package will be contained in a steel frame.

I'm hoping to make this a pretty versatile design, by having multiple tuyeres entering each side that can be closed off with ball or gate valves.

I've only used a washtub style charcoal forge with a botton tuyere made from drilling holes in a black iron pipe. So I'm not sure what diameter I should make the side jets. I was thinking 1/2" or 3/4" should be sufficient, but I'm guessing. I'm thinking 3 jets per side, should I use more?

I'm also wondering if I should fab a manifold to feed the jets, since my experience with the linear tuyere indicated that I won't see consistent air output across all jets without somethint like this?

Anyway, I appreciate any input on this in general. There is a boatload of concise info available about the finer points of coal forge design, but very little other than vagueries regarding charcoal. I'm not desperate for fire or anything, I've got running forges, so I'm looking to build the ideal here, not just "get something that'll heat steel" going. I just like forging with charcoal, and would prefer to stop using gas except when I'm making damascus.

[tomhw]

It sounds like an interesting project, Javan. If you are just beginning the blacksmith craft you might consider a forge design based on something tried and proven. Firstl gain some mastery and skill and you will then have a better grasp of how to make the kind of forge that fits your needs.

It is remarkable how little the equipment our craft has changed over the last several millennia. That is so because the skill of the smith is more important than his tools and equipment.

It's hammer time!

[Javan C.R. Dempsey]

I'm not a beginner. I hoped to make that clear. I have a firm grasp of my needs, but as I outlined, there are some variables i'd prefer not to have to tinker with too much.

It may be true that our needs haven't changed much over the course of the craft, but the near death of it, and the subsequent resurgence, has had an impact on the distribution of infomation and misinformation regarding it.

The use of coal as fuel in the scheme of the overall history of the craft is fairly young compared to charcoal, which makes it pretty ironic that there's so little information on the use of charcoal today. I hear a lot of repeated information, very little of it first hand, hell very little of it directly referenced from literature.


Anyway, apologies for the rant. I'll figure this out on my own, but I'd prefer not to waste time replacing piping, cutting new holes, etc, 10 times before I get it right.

[Ramsberg]

Hey Jevan,

The best advice I can give you is to make a small "test forge" .

One with a manometer, which is a balanced water column or coffee to see it better, in a clear tube which shows the air pressure, on the air delivery tube.

Then make a small section of the trough that you want to produce. Then fashion a bit of the wall out of a steel plate, with the ability to bolt on different outer plates.

Then make a bunch of different plates with different sized and shaped holes in it.

Not just round either, some with slits of different openings.

Then keep a record of the tests as to the total port passage area, head pressure on the air and shape and type of flame produced in the charcoal for that plates orifice at different air pressures.

This may sound like a lot of work, but it should be doable on a good Saturday or two.

Then with the information you have gathered with your test forge with its single orifice, which was designed to be easily swaped out, you will not only know exactly what size and shape of orifices you need, but you will be able to supply said infomation to literally THOUSANDS of other blacksmiths who are wanting to do the same thing or maybe something very different with charcoal!

Probably the most important knowledge you will gain is how the orifice shape and air pressure effects the flame shape and size.

My initial response to your question was going to be a suggestion to use a continous slot in the side of the forge with some kind of plate on the back of it to shape the area of the flame. Then I realized that although I believe it would work great, I honestly don't know for sure.

In other words. You pointed out that there is a great deal of lost and mis-guided information in blacksmithing, I couldn't agree more. Maybe your efforts with the shunned charcoal forge will begin to reverse that problem.

Caleb Ramsby

[ThomasPowers]

We certainly can't address your jet issue without knowing how it's being blown---sort of like asking "How big a jet do I need to produce 1 gpm of water? Without telling us if the water is at 1 psi or 10,000 psi.

Anyway that is a fairly wide forge for small jets of low pressure air. How I would do it is to not fill in around the jet area and test it with various sizes and see what works best for the set up you have.

For my Y1k forge with twin single action bellows and no check valves I use one 1.5" pipe flattened a bit as the tuyere with it centered and low in the side of the trough

My original adjustable length trough forge I used a bottom tuyere of a pipe with a ton of 1/4" holes drilled along the top 1/3 of it and than had a "ram rod" that fit in from the non-blown end to control how much of the trough would get air.

[Javan C.R. Dempsey]

Sorry good point, I'm going to start with a hand crank blower I've got sitting around. Its a champion, but not a big 400, when I played around with a trough type forge similar to the one you're describing Thomas, it delivered enough air to easily melt steel if I wasn't careful.

If for some reason that doesn't deliver enough air, I'll put a Kayne and Sons forge blower on it, and if that's not enough I've got a 440cfm high pressure inline blower. ;p. I'm thinking the hand crank will work.

I'm thinking of building a box below the forge body that will be the manifold, and just elbow out and back into the forge. Someone who's done a lot of work with charcoal on another forum is telling me that I'm going to need larger jets, but I am leaning toward doing some testing of the type Caleb describes. His idea of a sliding slot sounds very intersting initially, but I'm concerned that it wouldn't allow even air output, for the same reasons I need a manifold for the jets, unless I built air chambers much larger than the slot on each side?

I'm going to tinker with this some today and report back.

[John B]

If you have adequate air volume you should niot get pressure drops at the tues, we run 12 forges off one blower and none suffer pressure drops even when all 12 are in full competition use.

I am sure you are more than aware of this but I will point it out anyway,

When using charcoal, the fire will spread to the limits of the fuel in and around the pot, if you don't control the amount of fuel being used, by controlling the size of the fire, you will waste a lot of fuel,

IMHO Thomas's idea of the sliding adjuster is the best simple solution for adjusting the length/size and intensity of the fire

Good luck with the project.

[Javan C.R. Dempsey]

Aye I'm setting it up so that I can easily cut down the linear volume of tthe forge by dropping firebricks in.

[ThomasPowers]

For another off the wall suggestion: Can you find a set of table legs from the old tapered tables of the 50's and 60's---preferably painted and not chromed and then run a test where you trim them and stop when you get the size that seems to work best?

I use a couple of those legs for my bellows nozzles and have used them for spear sockets too.

[Arbalist]

First off, this is a very interesting project and I'd certainly like to see how you get on with this. The manifold idea sounds good and ball valves are pretty cheap. If you can make the tuyeres removable I'd just start with small holes, say 1/4" and enlarge them if/as required. Whatever you do I'd really like to see some pictures of your progress.
Good luck with the project!

Vic.

[Jacob Oberle]

Javan, your initial ideas for a multiple tuyere charcoal forge with manifold, ball valves, and box bellows bellow forge sounds exactly like i am invisioning for the forge i want to make. I may just go for it myself and i'll check back in once i have enough experience with it; if anyone is even still interested (I'm noticing now how old this post is...)

Unless you experimented with this design already and could spare me any mistakes.

by the way It's nice to hear I'm not the only one out there with seemingly crazy forge design ideas.

jake