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Dale's Rocket Powered Forge Bellows

Dale Hodgins

Joined: Jul 28, 2011
Posts: 5490
Location: Victoria British Columbia-Canada
Dale's Rocket Powered Forge Bellows

I've been immersed in YouTube videos about blacksmithing for the last few evenings. Watched everything from Vikings working bog iron to modern automated factories cranking out railway rolling stock.

One thing I've noticed with every small solid fuel forge is that all of them rely on some sort of powered bellows. Most forges employ something electric but sometimes a hand bellows or some other contraption is used. Often the bellows is left running while the smith forges the metal, so plenty of fuel gets wasted. The problem seems to be that the workers only have two hands. Even guys burning expensive propane often leave it burning away for lack of a foot operated means of turning it down as they head to the anvil. ------------------------------------------------------------------------------------------------------

I searched for rocket stove forges and some have tried them but have had difficulty reaching the nice white hot temperatures which allow for easier going. Just a few hundred degree drop in metal temperature requires far more hammering and it's hard on the hammer, anvil, work piece and the guy swinging that hammer. In order for a rocket forge to cook hot enough, it might need to be of large diameter and have an eight foot rise. That's just not practical for most folks and you'd have a giant flame shooting out the top similar to the one coming off Ernie Wisner's double chambered cob oven. A flattish work piece held at the wrong angle could easily channel that dangerous flame toward the blacksmith. ---------------------------------------------------------------------------------------------------------

Use a Small Rocket as a Bellows For a Charcoal Forge.

If a much smaller rocket of 4 to 6 inch diameter were used, the chimney could be built at the perfect height to set a metal or ceramic forge basket full of charcoal on top of the chimney. The rocket could be fed just enough fuel to keep the air flowing. This would allow plenty of oxygen rich air to go along for the ride. All of this rising air would rush through the charcoal, just as air from a bellows does. A sufficiently heated chimney would continue to draw air even when the fire is out. Thus, our charcoal would receive a stream of pure preheated air and easily reach forging temperatures. I imagine that something similar to a brick kiln with a chimney and an open face could allow gasses to escape while creating a radiant cap on the forge.

This configuration would tend to gobble quite a bit of charcoal if the basket were simply allowed to cook away full time. Therefore, we only want the bellows on the coals during metal heating and it needs to be interrupted while the blacksmith is forging on the anvil. There are several simple ways to accomplish this.

1. The basket is slid onto a stone or brick shelf beside the rocket stream between heatings. Super simple.
2. A foot pedal actuated baffle restricts rocket airflow when it's not needed.
3. The basket could be mounted on a swivel pin and another pedal could move a cable which swings it over the rocket stream when desired. Something as simple as a knot in the rope and a notch in a board could lock the system on “idle” or “full blast” as desired.

Any combination of these or other steps to interrupt the bellows would save both rocket fuel and charcoal.

Quite often, some simple fan such as a hair dryer is used to fan a small forge. Once the rocket fire is out, the air from one of these could be piped through a sealed feed door cover so that the hot riser can preheat the incoming air. A simple foot switch like those that control floor lamps could allow the blacksmith to activate the fan while both hands are occupied.

Does anyone have other ideas that could be employed to make a rocket powered forge more efficient and user friendly ?

Thank you: Dale Hodgins

Dale's picks - These are some of my favorite threads. Greed - My garden - ethics - Good wood bad wood Alder - Bees - Pulling nails -
Satamax Antone

Joined: Sep 24, 2011
Posts: 1590
Location: Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
Hi Dale.

N°2 is impractical, as it would smoke, and be the same as having an open forge imho.

Well, first of all, what do you want to do exactly with your forge? What kind of size and shape? Having a small fire underneath, that's not too daft. Could start the forge on wood. I mean, put wood at first on the bottom, which in turn would light up the charcoal or coal on top. But tending both fires could be a bit of a chore. This could be a solution. I think, forget about removable basket. Forge are fuel guzzlers by nature.

The other solution is a rocket forge with some mass in the riser. So it wouldn't loose succion when you open the door.

Satamax Antone wrote:

But it's a diferent type, it's not an open forge, but rather an oven type. Here, i've drawn it long, but could somehow be made square. That's why i was asking about what's the main purpose of the forge you want. If for long stuff, knives, swords, spears etc, what i've drawn could be adequate. If for doing stuff like spirals and the like for forged steel gates, doors etc, the long shape is no good. Then a square one, with two sides closed, and two sides with sliding up and down doors. Tho, that would afect the burn much, and the draft too, stealing air from the bottom flow through the grate. But i can't see any other way to do it, than oven style. Mind you, the Canyoon/Donket/peterberg batch rocket could also reach the proper temps.

Well, that's just my opinion.

God of procrastination Sad for sir Terry! 28 April 1948 – 12 March 2015
Robert Ray

Joined: Jul 06, 2009
Posts: 1339
Location: Cascades of Oregon
Purpose of the forge would have a lot to do with the design. I've never been able to get a real good weld with charcoal, but that might just be me, maybe a rocket type flame would allow that. Same with a gas forge great for forging but for what ever reason I still can't get the clean welds I achieve with coal. I' ll be interested in your results.

"There is enough in the world for everyones needs, but not enough for everyones greed"
Dale Hodgins

Joined: Jul 28, 2011
Posts: 5490
Location: Victoria British Columbia-Canada
My immediate forging desires can all be met by something the size of a laundry basket. Simple re manufacture of existing tools is the only forging I've ever done. Damaged hammer heads are 10 cents each at junk sales. The same goes for axe heads, big wrenches etc. I'd like to make some into adze, gouge type tools. I had one made from a leaf spring and it was great. I roughed out about 200 wooden bowls with it. Hinges, handles and hangers would be another interest. I doubt that I'll ever have the skill patients or inclination to make a high end hunting knife or a Samurai sword. Rustic functionality is all I want. I hope to never put more than an hour per pound into steel and iron items that I make. -----------------------------------------------------------------------------------------------------------------------------------

I want to start with something the size of a gas barbeque. I'll probably remove the legs from an old one and cut a 8 inch hole in the base so that it can be slipped over a rocket. I need this size of rocket as part of an outdoor kitchen, and once it's in place, I intend to try forging with it, smelting aluminium, heating a small moveable pizza oven etc. I'm viewing it as totally expendable, since the cost is very low. I have some ceramic experience and will create whatever is needed as I go along when it comes to grates, baffles, lids or whatever makes it work. There's a good chance that I'll melt one of those aluminium barbeques. If that happens, I'll make something far better out of clay and refractory materials.
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