John Martin

Building A Bellows

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I built a "great bellows" using 2 sheets of plywood so it was wider and longer than the above one. I used heavily impregnated canvas for the "leathers"---the tarpaulin stuff used to make wind wings for oil drilling rigs in OK and got it as scrap from a company that did make those for pretty much nothing.

I had no trouble with a fairly large diameter valve as I used light sheet aluminum and a very easy hinge. I covered the seal zone with felt---which quiets them down too!

For the nozzle an old late 50's early 60's conical table leg can be used and cut down till you get the size of orifice you wish.

I used this bellows for about 20 years and preferred it to my good hand crank blower which I preferred in turn to an electric blower.

I much preferred the double lunged bellows to the chinese box bellows I have used as there was a considerable time one could do other stuff while the top chamber was emptying with the bellows and with the box bellows air flow stopped as soon as you stopped pumping it.

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Shown below are photos that I took about an hour ago. I am using the same opening size and valve parts that I used for my wheeled Traveling Forge. The openings are 7" square as called for in the mid-1800s U.S. Army specifications for the Traveling Forge. For these openings I am using the following parts as shown in the picture on the right:
- Two 9" by 10" plywood blocks, 3/4" thick
- a 10" wide by 2ft long piece of baler belting from the local farm store
- Craft felt (either self sticking or use glue)
- an inexpensive dog leash
- craft sticks
- a couple of screws.
- latex gloves

As shown on the left.
1) attach the felt to one side of the belting
2) cut the belting to 1ft lengths
3) put on gloves
4) use craft sticks to mix and spread epoxy on wood blocks and attach to other side of each piece of belting
5) put weight on block to hold it firmly in place on belting
-----
6) when glue is cured, use screws to hold end without block to one side of opening, centering the block over the hole
7) use a piece of dog leash as a stop to prevent flap opening more than 45 degrees. Use screws to attach one end of the piece of dog leash to the top of the plywood block, and the other end to a spot in front of the opening, opposite from the screws. Length and location of ends of the piece of dog leash is determined by holding the flap open at 45 degrees.

The rubber belting acts as the hinge, and will last for a long long time. The felt quiets the valve and improves the seal. The piece of dog leash limits the opening of the valve to a 45 degree angle so that the flap does not get tangled in anything and the flap/valve responds quickly. The wood blocks serve to both act as weights and to keep the belting flat. This arrangement works extremely nicely on my wheeled Traveling Forge, so I can't recommend it higher.

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post-2340-0-54211600-1331167901_thumb.jp

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Hopefully this drawing will clarify a few points. The drawing shows which direction the valve should open and the limiting strap. The hinges for the valves in a traditional (non-Traveling Forge) need to be at the side towards the nozzle of the bellows. The strap limits how far the valve will open. The openings cut into the spacers above the valves, need to have the opening allow clearance for the valve to open. The upper valve should be far enough away from the bottom valve so that the bottom valve will, in the unlikely worst case situation, rub against the flat bottom of the middle-board and not against the valve opening in the middle-board.

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Another "grace note" is that you can build the valves on removable sections that mount into larger holes in the solid boards so that if there are problems on the middle board you can get in and fix it by removing the valve section on the outer board and then removing the inner valve. ISTR removable valve sections being used in De Re Metallica so it's not a new idea at all (500+ years old)

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If you want to try one of these:



You can find instructions in Hasluck's Smith Work downloadable from here:

http://www.wkfinetools.com/mLibrary/Hasluck/1904-smith%27sWork/1904-smith%27sWork1.asp

There was a video on youtube, someone made this other bellows but it seems the user closed his account and I think I can't upload a ~8Mb video here for you to see in use, but the plans are here:

http://cd3wd.com/cd3wd_40/JF/JF_OTHER/SMALL/04-084_blacksmiths_bellows.pdf

It seems it works very good; at least with charcoal (it needs less air)

Hope it helps...

Rubén

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If you want to try one of these:



You can find instructions in Hasluck's Smith Work downloadable from here:

http://www.wkfinetools.com/mLibrary/Hasluck/1904-smith%27sWork/1904-smith%27sWork1.asp

There was a video on youtube, someone made this other bellows but it seems the user closed his account and I think I can't upload a ~8Mb video here for you to see in use, but the plans are here:

http://cd3wd.com/cd3wd_40/JF/JF_OTHER/SMALL/04-084_blacksmiths_bellows.pdf

It seems it works very good; at least with charcoal (it needs less air)

Hope it helps...

Rubén

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I made the bellows from that second link. They've been working OK for about a year, but they are definitely not great. However, they only took me a few hours to make and all the materials were free, so no real complaints if you're looking for something cheap and easy to start out with. I got the tubes from a local garage, old metal strapping from the lumberyard, and the scrap wood I already had on hand.

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Thanks for the interesting discussion. I do contemplate to build double bellows to substitute for my foot driven rotary blower which does not supply any air once stopped.

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Rock star, if you spay out the first and last leaves and flip the center board you get just a bit more width. 

Inertube makes good leathers as well, especially if you are using canvas.  

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On 3/7/2012 at 5:57 PM, David Einhorn said:

Shown below are photos that I took about an hour ago

An excellent how_to!. Thanks.

I was unable to view your pics.

I used  ripstop nylon instead of leather. They worked fine.  

Also, I found that the action improved when I hung horse shoes on the end of the pole. I was able to add them until I got the action I needed. 

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Note that both "Divers Arts", Theophilus circa 1120 C.E. and "De Re Metallica", Agricola. 1556, include plans for building single action bellows for forges/foundries/smelters.

 

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