Side Blast Forge

[Tom Poelker]

I have built a double lung bellows and a fire pit for an 1820s historic recreation site.
The bellows will blow directly into the fire from the side.
I suspect that this will make a lot of difference in fire management.
Any resources on working with a side blast fire?
Any suggestions?

[eric sprado]

You will find it VERY Easy. Clinkers fall below the tuyere input so don't interfere with you fire. Remove them at the end of your forging session.

[Rich Hale]

I believe there is some good information in the area below this thread under forges........

[Dan P.]

What kind of tuyere are you using?

[Frank Turley]

We can't see what you've done, but the British book, "The Blacksmith's Craft" has good sections on the construction of a side-blast, water cooled tuyere in Chapters 1 and 3. Chapter 3 addresses fire management. This book can be downloaded: http://www.hct.ac.uk...blacksmith.html.

J. E. Hawley's book, "The Blacksmith and his Art" shows the construction of a side-blast forge. Hawley used wet wood ashes as a base under the fire.

[HWHII]

Here is one that I built. I got the plans for the water tuyere from Dave at Dave's Welding. They came from a old California Blacksmiths Associations news letter. Mark Aspery provided the drawings and article. Dave builds one's simular to this one and sells them. Mark Aspery likes and uses his type of forge when he does his demonstrations. Hope this helps.

[Farmall]

Mr. Turley, the Herefordshire School of Technology has rearranged their website. I found that out when I used your link. The new location of the "Blacksmith's Craft" is here:

http://www.hct.ac.uk/Downloads/cp_blacksmith.html

[silkhopesmith]

I doubt you will find any evidence for water cooled tuyers in th 1820's. Most mention of them is 50 years later. Before you decide to make one you might want to look at period sources.

[Don A]

Mr. Poelker,

Will you be using charcoal? I assume so for 1820's.

I use a side-blast with bellows rig at the historic site where I volunteer. My "forge" is pretty much a large iron angle with a 1.5" pipe welded at bottom center. I keep a selection of fire brick handy and arrange them for whatever fire width/length/depth I might need.

If you are using charcoal, try to arrange your forge so that you can have 4 or 5" fuel under the work with about as much over it. You will be suprised how little air you need in a good, deep fire, especially with smaller stock.

[ThomasPowers]

Location? An 1820's historic site in England might use a different fuel than an 1820's historic site on the American Frontier; or in South Africa or Australia...

[GregDP]

Hi Mr. Poelker. Nice to meet you. I'm assuming you've spent a little time at the forge. I'm not really a voice of experience, but sometimes that can be a good thing.
As a relative novice I can tell you what my impression of a using bellows and forge has been the few times I've helped Solvar demo. I've been really spoiled by electricity!

Side or bottom draft it doesn't matter. Fire and hot air rise. A side draft forge can change the type of fire you have, but not as much as I thought it would! There is an extra level of control over how far your fire spreads. Most often, when air enters from the bottom of a fire, it hits the fuel and diverts in every direction. But! With a side draft forge something great thing happens. You can really control the reach of your fire. This is the single most useful aspect of this sort of fire.

The calorie powered forge and bellows I used were crafted with medieval wood cuts in mind. They were not troublesome to manage alone. The lever action helped with the weight of the bellows but I found it less tiring to lift more, but move less distance. The bottom lung pumped air into the hearth while inflating the top. A powerful blast could be encouraged with practice. Charcoal was the primary fuel. It was great for the small demo projects we were doing. I did find the back wall difficult to get used to working around. It's perfectly functional on 180 degrees. But for some projects it would require you to switch sides. This was only bothersome when using two anvils and two halves of the fire. The back wall did a great job protecting the small steel tuyere.

The one I made used coal. It had a 1"x1' to pipe for the air blast and was crudely crafted from clay and brick with an electric blower. The air blast was about 3/8" from the bottom of the forge. It worked well, but there was a flaw. It was possible for coke to be pushed into the pipe. It could be blown out with too much air. Even so it didn't get too hot. It was well insulated and I could even mound coal over it without problem, but I seldom let the fire spread that far.

I do not want to underplay the value of fire management, but I don't want to make it seem too intimidating either. Honestly, fire is fire is fire. If there is fuel, oxygen and enough heat, fire will occur. It will grow and you'll get used to it. :) I'd love to see some photos of your build!

[David Einhorn]

Here are some "side blast" forge images. To help clarify conversation the term side blast usually refers to air being blown into the forge, and side draft usually refers to air leaving the forge through the side arrangement of the flue opening.

From left to right the images are:
- On the far left, plans for the forge shown in the image of the forge on the far right.
- A patent for a portable army forge that is very similar to the image of an earlier naval forge shown in the picture from the Monitor Leigh.
- A U.S. government drawing of a mid-1800s portable forge used by the U.S. Army.
- A picture of a forge being used on the Monitor Leigh circa 1863.
- A picture of a wheeled mid-1800s U.S. Army "Traveling Forge" that I built over a four year period.
- Picture of the forge I built that is shown in the drawing on the far left, inspired by the photo of the Monitor Leigh, but not an exact copy. Sorry I don't have a picture of it finished.

[John B]

The one I made used coal. It had a 1"x1' to pipe for the air blast and was crudely crafted from clay and brick with an electric blower. The air blast was about 3/8" from the bottom of the forge. It worked well, but there was a flaw. It was possible for coke to be pushed into the pipe. It could be blown out with too much air. Even so it didn't get too hot. It was well insulated and I could even mound coal over it without problem, but I seldom let the fire spread that far.

The 3/8" above the bottom of the forge is a certainly a flaw, the air outlet needs to be at least 3" (preferably more) above the base of the fire, this not only helps reduce coke entering and blocking the tue, it's main advantage being to allow the clinkers to form well below the fire itself allowing for longer working time before having to remove the clinker.

Just as a matter of interest to anyone considering making a side blast arrangement, a 3/4" diameter air exit is adequate and economic for most situations, stepping up to 1" plus increases the amounts of fuel used, even with good fire management, this larger size is normally used in commercial situations with a large throughput of industrial type and larger sections of materials (2" plus)

Even a 3/4" diameter set up is capable of firewelding 2" square wrought iron, may need a little patience, bit we have done it, so know it is possible

[GregDP]

Mr. Einhorn thank you for taking the time to clarify that. I learned the terms wrong reading about forges online and it's been tough to shake the bad habit. I'm draft daft. :P
The one inch black steel pipe, I think has a smaller ID than 1". But it certainly was an awful lot of air. My original design didn't have a brick on the far side on the fire pot, but after a short test it proved necessary to keep a deep fire. I never set out to make a sideblast forge but only make a forge I could use. I'd really like to try another style to ovoid those pesky little bits.
3" in my mind that seems high, I guess that's just the bottom blast mentality kicking in.. Lots of room for clinker, but how big would that make the rest of the hearth. My imagination is running away with me as I try to envision it I'm weighing out many pro's and con's!
I've always found clinker troublesome and end up moving my fire upward as the day goes on. Starting out lower just seems like a great way to worry about building taller fire less. You've inspired me.

[John B]

Hi Greg,, it does not effect the rest of your hearth size, only the depth, beneath the tuyere where it is within the hearth, and 3" is a modest depth, most of the ones we use have between 4" to 6" deep below the centre line of the tue.

In practice with a sideblast forge, irrespective of the actual base to tue centreline, the height of theworking fire is more constant, the clinker forming below and in front of the tue rather than forming a false semi solid base to your fire as is the case when using a bottom blast. It is also more easily identifiable as to when clinker removal is needed than in a bottom blast hearth.

This clinker formed is easily removed without overly disturbing the working fire as it trickles down into this space beneath the tue, and coagulates there, switching off the air blast for a few minutes allows you to remove the clinkers usually in one piece using a poker and slice

The main problem with the side blast forge is the loss of tuyere length over time as the front burns back, this obviously depends on what fuel you are using, the tuyere's material, and the length of time the blast is on, this is overcome by the introduction of a water jacket and bosh, however this does affect the footprint and size of the hearth, and you also need a convenient water supply, for a small footprint a bottom blast forge is the way to go.

[HWooldridge]

John, do you fill the entire hearth with dirt or ash, or do you use coal/coke in the whole thing and let it form a natural firebed?

[John B]

John, do you fill the entire hearth with dirt or ash, or do you use coal/coke in the whole thing and let it form a natural firebed?

Firstly you need an area in front of, above and below the tue that is the working area of the fire itself, This area is at a convenient position in the hearth itself. (This is the equivalent of your bottom blast fire pot).

The front of the tue is positioned away from the back of the hearth, and there is usually a vertical wall at the rear of the hearth, this is where you can pile new fuel to rake down and use in the fire itself when working, there can also be high sides (with cut outs for pass through situations) or relatively low sides. High sides give more opportunity to feed the fire from other areas when it is lit and you are working it.

The only area you need be concerned about is being able to sustain a fire, and to feed that fire, the surrounding spare volume is immaterial, and so can be filled in as you please,

If making a new hearth, I fill in the spare area with anything suitable to give a levelish area to the top of the tue whilst leaving the fire pot area clear, this could consist of old firebricks, dry sand, or old ashes and cinders if you have any, it is just to bulk it up and save using fuel which is expensive and will eventuially be reduced to a dust filled mass, so don't waste fuel, just fill the void with an appropriate substance.

It has been observed that a new hearth that has been filled using coal, after being first used, and then left overnight, the whole hearth was found to be glowing the next day as the fire had spread through the coal, feeding off this excess new fuel, a total waste of money when ashes or other infill could have been used in the first place. (but thats the voice of experience)

With the side blast, if you need a bigger fire, you stack it higher and wider, but it is still in the same relative position over the top of the tue, so the actual "fire pot area" remains reasonably static. Just clean out any excess dust and clinkers before starting up each time.
At the end of the working day because we are in a safe environment and coke goes out quite rapidly, I tend to just shut down the airgate and leave the clinker to set, it can then be easily removed (along with any excess dust) before starting the next session.

[Dan P.]

Here is how I prep my forge bed;
Ash and dusted wetted, and formed into a little nest directly in front of the tue. I would say the top of the tue hole could be level with the top of the surrounding bed, something like that. I used a tin can as a form around which to mould the dust, which is thoroughly wetted and tamped down. It keeps the fire nice and tight. I have to do this once every while. I'm also of the school who leave their clinker where it is, only removing it first thing in the morning.

[Dan P.]

Sorry, double post, but I will take the opportunity to add that tinned jackfruit are not worth buying. They're just sweet and bland.

[Frank Turley]

DanP,

What is beneath your dampened nest, some sort of bed, and how deep? The COSIRA book says "burned cinder and ashes." I've also read "clay," "dirt," "rubble & dirt."

Thank you.

[Dan P.]

Frank, underneath the bottom of the nest is maybe an inch of ash, then firebrick, then the bottom of the forge. Otherwise that particular forge bed is padded out with rubble and sand. Any non-combustable will do, as long as their is a flattish part for the coke supply to sit on, and a downish part for the fire to go in, and it's not going to get too mixed up in your coke.
It is important to have some ash between the bottom of the nest and the firebrick because, as I'm sure you know, the clinker will fuse with the firebrick.
To build the first ever fire bed I have always been lucky enough to have been able to take the ash from another forge. Failing that I suppose any non-clinkering (i.e. not sand!) ash type material would do.

[Countryforge]

A while back I built a side draft 6 inch high sides the tuyre is 3 inches from the bottom but I have a 1 inch piece of fire brick stopping the heat from traveling to the bottom, see thread "English forge" on "solid fuel forges" for some pics showing the Boss assembly

[kubiack]

I’m about done building one based on Mark Asprey’s plans. I used his design for the blast pipe/tank and chimney. I talked to Mark before I started to get some more details on the rest of the forge and its use. You can see the details here http://www.iforgeiron.com/topic/26716-side-blast-forge/. I just have to finish the tong and fire tool holders and put a coat of paint on it. Ill be posting some pictures once its finished.

Dan P, thanks for the detail on the fire bed. I did something similar when testing my forge but had no ash and had to use dirt instead. How well does the bed build of ash and dust keep its shape through a days worth of forging?

[Dan P.]

How well does the bed build of ash and dust keep its shape through a days worth of forging?

Not very well. Certainly if I am going to need a clean, good fire for something delicate I will just make it new.
Otherwise it is impossible to say when it "generally" needs to be re-done. Every fortnight maybe?