Fenrisulfr Posted December 10, 2015 Share Posted December 10, 2015 Since i'm tired of using an airdrier and leather is pricey i've been looking to make some cheap bellow for my new forge i plan on making,and i came across those japanese bellows,I like working wood and it doesn't cost a lot,surely less than leather or an old forge bellow,and they look like they blow some air!Too much to be honest!One problem i had with my air drier is that it blew too much air and since i'm using charcoal i've been told i don't need too much. I've understood how those bellows works but all the ones i saw on video looks to blow like a tornado.Anyone has made a medium-small sized one and can share the measures with me? I wouldn't want to mess it up or make it so small that it's doesn't work well. Quote Link to comment Share on other sites More sharing options...
Kozzy Posted December 10, 2015 Share Posted December 10, 2015 Maybe I'm not understanding which style you are speaking of but every image for "japanese box bellows" is hand operated and therefore you would control the airflow by the speed you "pump" Here is a dimensional drawing of one--a couple of others come up with dimensions also in a google image search. Quote Link to comment Share on other sites More sharing options...
Fenrisulfr Posted December 10, 2015 Author Share Posted December 10, 2015 Ik that but in many videos i've seen even when they were moving the panel just a few inches it looked to blow a lot of air, i'd like it to be as small as i can. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted December 10, 2015 Share Posted December 10, 2015 Note that I built the prototype for my Y1K twin bellows using Naugahyde from a discarded couch, the wood was an old thrown out printer cabinet---nicely oak veneered plywood. I figure I spent less than a dollar building it---mainly for the nails. For my big double lunged "great bellows" I used the heavily treated canvas used on oil wells---went to a place that made them and got the scraps---that only worked for 20 years; well it was still working great when I moved 1500 miles and it went to a friend as I ran out of space to pack it. Please take off your aluminum hat so we can read your mind about how big your forge is and how you will be using it (fuel, how often, size of work, forge welding, etc) Details are needed to make specific suggestions! (I have a friend who considers 1' diameter stock as "small" where he works pointing out that such terms don't convey information well...) Quote Link to comment Share on other sites More sharing options...
Fenrisulfr Posted December 10, 2015 Author Share Posted December 10, 2015 I need to redo my forge but it won't be very big,something like 15 cm width x 30-40 cm in length,covered on the long sides with refractory bricks.I work stuff like knives,jewelry and axes. Quote Link to comment Share on other sites More sharing options...
Kozzy Posted December 10, 2015 Share Posted December 10, 2015 Those plans are basically designed to use a single sheet of plywood. You might save a little space building smaller but probably not cost or labor. The plan shown has an internal dimension of roughly 1.8 square feet. Just for kicks, say that one could move the piston at a rate of 1 foot per second (4 seconds for a full stroke) without being too over-taxing: That translates to about 110 CFM. A shorter box (smaller in length only) would just mean changing stroke direction more often and losing a little work efficiency but not much. Compare that 110 cfm to many of the blowers advertised which seem to run in the 135-165 CFM range--and tend to be choked down a little by a gate. Quote Link to comment Share on other sites More sharing options...
hiltsbilt Posted December 31, 2015 Share Posted December 31, 2015 Mine are way big, about 4 foot long and I still don't have a problem controlling the air flow. But I would make them about 3 foot long if I made a new set :-) Quote Link to comment Share on other sites More sharing options...
hdvoyager319 Posted October 14, 2019 Share Posted October 14, 2019 I am interested in building a Japanese Box Bellows. The Push Rod travels about 4' per stroke, push about 12,700 cubic inches of air per stroke, double action. Push/pull the PushRod 4' per stroke seams like ergonomics issuet because of the stroke length. Has anyone shortened the stroke by increasing the cross section area of the piston? A piston measuring 24" X 18" area would push about the same volume of air with a 29" stroke as by the 24" X 11" area with a 48" stroke. The air flaps would need to be increased in size to allow the free flow of air with the short stroke piston. The effort to move the piston may increase because of the increased area of the piston and the resistance of the outlet air tube's diameter. With the box bellows resting on the ground under the forge, the blacksmith could attach a vertical pivoting lever to the push rod to make pumping easier.. Add a counter weight system to the lever, all the blacksmith would need to do is pull the lever handle and the counter weights would push the piston back while forging. The forge fire wouldn't cool as much because air would be pumped continuously to the fire. The blacksmith would operate the lever back and forth to pump the needed volume of air to the fire. The bellows system would be positioned so a right or left handed blacksmith could pump the box bellows with their dominate arm. My forges, Rivet and stationary, have the rotary blower set up to the left of the forge for a right handed blacksmith. Being left handed, forging and cranking with the same arm is doubly tiring. Has anyone altered the box bellows piston size and/or changed operating push rod to operate with a lever as discussed above? Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted October 14, 2019 Share Posted October 14, 2019 First of all; how much air does your forge need? Picking a random number out and trying to build to that is not a good idea if it turns out you only need 1/2 as much... Fuel affects how much air you need. If you are using real charcoal you will not need much air as you do for coal. Size of the forge and intended use does as well. Note that the box bellows does have a zero flow point in the crossover from pull to push. For a true continuous flow you need something like the european double lunged bellows where the top lung is just air storage and so intermittant pumping keeps it charged for continuous flow. I have used a large box bellows built by Ric Furrer; it's stroke length was under 2' as I recall. I preferred my large double lunged bellows as I could pump up the top chamber and go get a tool or a drink of water before I needed to pump it up again. I could pump it to a welding heat using just my pinkie too! (The size of the top lung and weight on it and diameter of the nozzle affects how long it takes to empty.) The box bellows requires continuous pumping. Where the box bellows excels is in the Space required and portability! Adding counter weights means that you have to lift the extra weights every stroke making it more tiring. Quote Link to comment Share on other sites More sharing options...
anvil Posted October 14, 2019 Share Posted October 14, 2019 I've not used a box bellows but I have built a great bellows. I agree with Thomas. A great bellows is a joy to use. I used rip stop nylon instead of leather and old pine tongue and groove flooring for the woodwork. I was in a 12'x12' old 1930's garage. I hung it from the ceiling to save space. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted October 14, 2019 Share Posted October 14, 2019 They are great it made and installed correctly; as mentioned I could pump mine with my pinkie. A smith I knew worked at a "historical village" where they had converted a building to a smithy and put the bellows overhead but had the handle for the bellows hooked up such that he had to wrap a strap around his arm and haul down with a lot of force to get it to work---blew out his shoulder and hip after working with it for 10 years. Quote Link to comment Share on other sites More sharing options...
hdvoyager319 Posted October 14, 2019 Share Posted October 14, 2019 I am left handed so having a box bellows that can be moved to accommodate either a left or right handed blacksmith or student will be a huge plus. How does a Box Bellows compare to a Traditional Bellows and to a rotary hand crank blower to maintain a hot forging and welding fire? The fuel I will be using is Anthracite Nut coal mixed 50/50 with Bituminous Blacksmith coal. I have tried the combination and found that it works. The Bituminous coal keeps the Anthracite coal burning, the flames from the Anthracite coal eats the smoke from the soft coal. They both coke nicely. Since the portable Side Blast Forge is in the planning stage, I don't know how much air will be required for forging and welding. Is the Box Bellows intermittent air blast a problem for welding? From the above comments, it is encouraging that the box bellows is very easy to pump. What are the bore and stroke dimensions of the box bellows that you use? Quote Link to comment Share on other sites More sharing options...
anvil Posted October 15, 2019 Share Posted October 15, 2019 18 hours ago, hdvoyager319 said: They both coke nicely I suggest you try burning just your bituminous coking coal by itself. I suspect you will find you get a better coking fire just using it. Also, if you keep the green coal out of your coke, it won't smoke Quote Link to comment Share on other sites More sharing options...
hiltsbilt Posted November 17, 2019 Share Posted November 17, 2019 opps Quote Link to comment Share on other sites More sharing options...
hdvoyager319 Posted November 17, 2019 Share Posted November 17, 2019 I am also interested in building a box bellows system. Just thinking about the criteria of the Box bellows, the stroke should be relatively short, yet be easy to push/pull while delivering the needed volume of air to reach welding heat. I like your idea tp be able to pump from both sides. My current side blast forge set-up has the anvil and power hammer on one side and the vice on the other side. Currently I will be using an electric blower until the Box Bellows are built. I watched a video of a Japanese sward maker using a Box Bellows. It appeared that his normal stroke was a little over 2' but when he went to welding, the stroke was reduced to about 1' but with very fast strokes. The air blast in his forge didn't appear to be interrupted when welding as was with the full stroke used while forging. 18" x 18" x 20" stroke gives a 650 cubic inch volume per side. If adequate volume of air is achieved by short pumping the existing bellows, then increasing the piston to 21" x 21" decreasing the stroke to 13" per side you would have a volume of 570 cubic inches per side. I believe that a total in/out stroke length of 26" would be easier to manage than the 40" or longer full stroke. Short stroking the 18" x 18" piston would give much less air volume. The larger piston will increase the pumping effort unless all the air inlet and air outlet openings are enlarged to the maximum possible extent to reduce drag. . The air outlet pipe would likewise need to have the ID increased as large as possible. From what I have read, the box dimensions are determined by what can be made from a 4' x 8" sheet of plywood. Going with different box piston size and stroke length dimensions, probably will require more than one sheet. Quote Link to comment Share on other sites More sharing options...
pnut Posted November 17, 2019 Share Posted November 17, 2019 2 hours ago, hdvoyager319 said: The larger piston will increase the pumping effort unless all the air inlet and air outlet openings are enlarged to the maximum possible extent to reduce drag. . The air outlet pipe would likewise need to have the ID increased as large as possible I think you're correct. If you don't increase the air outlet pipe I think you would have to pump very slowly or risk blowing the coal out of the firepot. Especially if using charcoal. It's a balancing act between air volume and air pressure. Pnut Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.