For a long time I wanted a homestead blacksmithing shop, and finally have located an anvil and have a shed to house all the equipment. The shed is off-grid with very little hope of ever having electrical service, so I need a manual method to supply air to the forge. Traditional leather double action bellows are beautiful, but very complex to construct. Fortunately Youtube has a wealth of blacksmiths who have explored a whole range of forge blower options. Many bladesmiths and knife makers have excellent videos showing the construction of Japanese Fuigo style box bellows. These are large units usually that supply large amounts of air to long forges for swordsmithing.

I do not aspire to bladesmithing, but a bellows constructed of wood was a very attractive concept as I have most of the necessary tools and skills for woodworking. In the process of researching designs, I came across the design for a Chinese/Korean style box bellows. In principle it is very similar to a fuigo, with the primary difference being that the plenum chamber is located inside the piston chamber where the Japanese Fuigo has a separate external chamber for the plenum. Without the ability to test either design and not having any real understanding of the pros and cons of each one, I decided to use a version of the Chinese/Korean style. My main reason was simply ease of construction. With the internal plenum I could construct the plenum with three small boards and have a compact unit with all parts having easy to fabricate 90 degree angles, with the possible downside of having to reduce the size of the piston. I was also unable to figure out how the plenum valves are arranged in a traditional box bellows of this style, so I added two valves in a similar position to the way a fuigo plenum valve system is set up.

The dimensions of my bellows were mostly dictated by the available materials I already had and a piston travel that seemed comfortable (24 inches). The box is 30 inches long, 12 inches tall, and 9 inches wide. The piston is approximately 8 inches square, and the plenum chamber is 3 inches by 8 inches by 24 inches. I used a single piston rod made from scrap copper pipe with an outside diameter of 5/8ths inch ( I believe it is 1/2 inch pipe but I'm not very familiar with plumbing sizes and terms).

After completing the bellows I successfully hooked it up to my forge and heated up some scrap rebar to a bright orange heat which was very exciting.

Here's the video with Mors Kochanski where I first saw this style box bellows. You can see that the plenum valve is different from what I've built, but I could not figure out how their arrangement was set up, and I couldn't find a good image of one of these valve setups online.
   • Blacksmithing Piston Bellows  

I also found Dave Foote's channel to be incredibly helpful as he worked through the process of building a very nice bladesmithing bellows. I highly recommend his series of videos about his fuigo build.
   • Japanese box bellows  
   • Japanese Box Bellows 3  
   • Japanese Box Bellows Part 4  
   • Fixing the box bellows  

All in all it was a really satisfying project, very rarely do I build something that I am 100% happy with, but this one made that cut.