rdennett Posted July 28, 2012 Share Posted July 28, 2012 I am trying to help a friend who is new to blacksmithing set up a forge where he has no access to electricity. I myself have a small double lung bellows that I constructed, but I was hoping to figure out a good way to construct a centrifugal fan from easily obtainable junk using minimal tools. A Japanese-style box bellows would be good to, but without a table saw or something that can make straight cuts in plywood, it is difficult to get the piston to work correctly. They also tend to be heavy and bulky and this may need to be portable. Right now, I am trying to figure out to improvise the bearing and pulleys or sprockets and shaft collars that would be required. My friend does have access to an auto body yard. Any good blowers in there he might look for? Also, any pictures or videos of homemade hand-cranked blowers would be awesome too. Thanks, Rob Quote Link to comment Share on other sites More sharing options...
Gundog48 Posted July 28, 2012 Share Posted July 28, 2012 With access to an auto yard your best bet is to get a snail shell type blower from a vehicle, basically the biggest one you can find, I'm using a demister fan from a bus which is incredibly powerful. Bring a 12V car battery and take it back and charge overnight. Really simple solution and probably the easiest to pull off. Judging by your choice of language you're not from the UK, but if you are I can get you a duel fan bus demister fan that can push 700CFM on 24V and about the same as a crank blower on 12V and ship it to you for a reasonable price. They cost about £200 but I have a source for used ones! If you definitely want to go with a hand-operated unit- I've seen ones that utilise an old bicycle mechanism to get the gearing. You could salvage one of these fans and drive it with this mechanism. Making the actual 'fan' part would be difficult if you wanted to do that yourself, but it has been done many a time with sheet metal. I'm sure someone will be able to provide a link to a project. Quote Link to comment Share on other sites More sharing options...
Sweany Posted July 28, 2012 Share Posted July 28, 2012 A friend of mine refit an clothes dryer blower to hand crank operation, It worked pretty good Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted July 28, 2012 Share Posted July 28, 2012 I must be missing something here; would there be anything wrong with a typical Champion or Buffalo hand crank blower? They can often be found for not much money and do the job nicely... Quote Link to comment Share on other sites More sharing options...
Glenn Posted July 28, 2012 Share Posted July 28, 2012 A Japanese-style box bellows would be good to, but without a table saw or something that can make straight cuts in plywood, it is difficult to get the piston to work correctly. Hand saws have been used for years before the table saw was invented. Why not a box bellows from a piece of plastic pipe. No one ever said it had to be square. Quote Link to comment Share on other sites More sharing options...
iron woodrow Posted July 28, 2012 Share Posted July 28, 2012 700cfm at what pressure, gundog? Quote Link to comment Share on other sites More sharing options...
Gundog48 Posted July 28, 2012 Share Posted July 28, 2012 The original output has almost zero static pressure, but with the adapter box that brings it down to a smaller size to fit the pipe, the pressure gets pretty high. Pressure is really more important, but try telling my old forge that! I tried seeing that this could do at full blast and it melted the steel body! Quote Link to comment Share on other sites More sharing options...
rdennett Posted July 28, 2012 Author Share Posted July 28, 2012 I must be missing something here; would there be anything wrong with a typical Champion or Buffalo hand crank blower? They can often be found for not much money and do the job nicely... Define not much money. I don't see them for much under $100 and that's before shipping. Thanks, Rob Quote Link to comment Share on other sites More sharing options...
rdennett Posted July 28, 2012 Author Share Posted July 28, 2012 Hand saws have been used for years before the table saw was invented. Why not a box bellows from a piece of plastic pipe. No one ever said it had to be square. What kind of pipe? What sort of dimensions do you need? Also, hand saws are great, but it takes a lot of practice to cut straight lines with one. I don't know if my friend is sufficiently adept with one to produce adequate parts. Thanks, Rob Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted July 29, 2012 Share Posted July 29, 2012 Define not much money. I don't see them for much under $100 and that's before shipping. Thanks, Rob Well, everything is relative but by the time you build a bellows or blower, you might well have $100 in it. If I was trying to do somethng as cheaply as possible, I'd look at repurposing a leaf blower. They can be found on Craigslist for as little as $25 or maybe a bit more. Lots of pressure with about the right CFM for a forge. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 30, 2012 Share Posted July 30, 2012 I've built a bellows for about US$1 before, not much in the way of straight lines needed either. Also look at how Weygers built a "self blowing" forge using apiece of pipe and a paint can---it's in "The Complete Modern Blacksmith" which if you are in the USA you can almost certainly get at your local public library using ILL. As for pipe---PVC pipe, easier to work with minimal tools, lighter and easier to find in large diameters. Quote Link to comment Share on other sites More sharing options...
rdennett Posted August 2, 2012 Author Share Posted August 2, 2012 I actually have a copy of Weyger's book. Will the draft on that forge really create good forging temps? Also, I am not sure where to get PVC pipe over 6 inches in diameter. Would that be enough? If so, how long would it have to be. My bellows are roughly 2' x 3' and barely adequate. What volume of air does a bellows need to displace at a stroke assuming you aren't Superman? FYI, here's a link to a pic of mine on another forum: http://texasbushcraft.forumotion.com/t475p15-homemade-forge#3796 Thanks, Rob Quote Link to comment Share on other sites More sharing options...
Jeff Lodge Posted August 2, 2012 Share Posted August 2, 2012 Got an old bike laying around? You can use the chain, sprockets, and pedals for the gearing, then build a box and fan out of wood and mount the drive sprocket to the fan and there ya have a hand crank blower. Quote Link to comment Share on other sites More sharing options...
rdennett Posted August 2, 2012 Author Share Posted August 2, 2012 I thought about that, but the trouble is that the drive sprocket is on the inside of the frame. When I have seen people use bicycles for this, I believe they typically remove the back tire and rig up some kind of belt to go around the hub and a pulley on the axle of the blower. I am not quite sure what I have to work with there. Thanks, Rob Quote Link to comment Share on other sites More sharing options...
VaughnT Posted August 3, 2012 Share Posted August 3, 2012 Look for an old hand-powered bench grinder at the flea markets. Had a guy on here post a thread where he took the stone off and attached a home-made impeller and housing. The grinder is usually very cheap and gives you the gears and crank already in place. All you need to do is make a sheetmetal impeller and surround..... Quote Link to comment Share on other sites More sharing options...
rockstar.esq Posted August 9, 2012 Share Posted August 9, 2012 I built a box bellows out of a single sheet of plywood, a ball of string, a yard of felt, and a box of wood screws. I learned that a 12" square piston on a 42" stroke puts out WAY more air than a hobby forge needs. If you can get 4" diameter PVC you could gang several pistons together with fairly short strokes. A very simple way to cut PVC pipe is nylon string. Just wrap it around the pipe and pull it back and forth shoe shine fashion. It cuts quite well. Another advantage of the PVC pipe is that you can buy straps, brackets, and fittings for it. Electrical conduit is roughly the same size, all the brackets will fit. To make pistons you can buy pipe caps and trim them to fit the pipe's ID. If you use a propane torch, stove, or campfire to soften the plastic, it cuts much smoother and faster. I've also ruminated about the potential of recycling HVAC round duct since that's VERY easy to come by. Gundog is right that forging is more about air pressure than speed. Blowers are way different than fans. Hand crank blowers are the ultimate evolutionary solution to your problem. For me, $100 for a hand crank blower was too much. Since this is my hobby, I can't "charge an hourly rate" to what I build. If I were trying to make production, $100.00 is no hurdle. Quote Link to comment Share on other sites More sharing options...
JNewman Posted August 9, 2012 Share Posted August 9, 2012 Stop by a construction site doing sewer work with a six pack and you should be able to get some short pieces of large diameter PVC pipe. I have seen pictures of blowers built in third world using a bicycle wheel just attach some flat pieces of wood or plastic to the spokes to make your impeller. With the amount of air you will move with a wheel sized impeller your volute will not need to be that efficient. With a bmx sized wheel two plastic trash can lids and some duct tape you could make a pretty good blower. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted August 9, 2012 Share Posted August 9, 2012 Don't need that big a diameter of pipe---take a look of the pipe bellows used on Java for blowing forge fires for forge welding of kris's they just use a section of bamboo and chicken feathers on a stick! Quote Link to comment Share on other sites More sharing options...
rdennett Posted August 15, 2012 Author Share Posted August 15, 2012 Stop by a construction site doing sewer work with a six pack and you should be able to get some short pieces of large diameter PVC pipe. I have seen pictures of blowers built in third world using a bicycle wheel just attach some flat pieces of wood or plastic to the spokes to make your impeller. With the amount of air you will move with a wheel sized impeller your volute will not need to be that efficient. With a bmx sized wheel two plastic trash can lids and some duct tape you could make a pretty good blower. I am not quite sure how to do the bicycle thing without cutting off one side of the frame and rig up some kind of bracket to support the now-unsupported side. Is there another way you had in mind? When I see images of third world smiths using bicycles to power their forges, they are using the rear wheel as a large-diameter pulley to drive the small pulley on a blower spindle. The idea of ganging together several short pieces of PVC sound interesting, but I am not quite sure how to rig up the valves (unless you are not talking about double action bellows). Still, I will pass this along. I think my friend may have lost his fire for the project. To be fair, not too many hobby smiths forge in Texas in August. Rob Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted August 15, 2012 Share Posted August 15, 2012 Shoot I must know dozens of hobby smiths forging in TX, LA, NM, GA, FL, in the summer. Valving can be as simple as leather flappers glued over largish drilled holes---in the side of the PVC for a double action pipe and in the wooden piston/ends for a single action. Quote Link to comment Share on other sites More sharing options...
Woody Posted August 15, 2012 Share Posted August 15, 2012 Uh Guys...... The wheel has already been invented and so has the forge blower. Time is money any time you spend building something that you could purchase rather inexpensively you are spending time that could be better spend making things that you could sell. My first forge was a double habachi with my shop vacuum for an air supply. First time I kicked on the vacuum it pretty much took care of the eyebrows. If you hook a leaf blower to it stand way back the first time you light it off. :rolleyes: Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted August 15, 2012 Share Posted August 15, 2012 Sometimes it's the journey that's more important than the arriving. Quote Link to comment Share on other sites More sharing options...
Frosty Posted August 15, 2012 Share Posted August 15, 2012 Uh Guys...... The wheel has already been invented and so has the forge blower. Time is money any time you spend building something that you could purchase rather inexpensively you are spending time that could be better spend making things that you could sell. My first forge was a double habachi with my shop vacuum for an air supply. First time I kicked on the vacuum it pretty much took care of the eyebrows. If you hook a leaf blower to it stand way back the first time you light it off. :rolleyes: Don't forget to have your fire insurance paid up, just don't let the adjuster know about the leaf blower. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted August 15, 2012 Share Posted August 15, 2012 I started smithing with an electric blower around 1981. When I acquired a good hand crank blower I found I preferred it to the electric one---save for billet welding. When I built and tweaked in a double lunged bellows I found that I liked it over the hand crank blower---except for billet welding and transportation! Quote Link to comment Share on other sites More sharing options...
Unforgivun Posted August 15, 2012 Share Posted August 15, 2012 Look toward the bottom. Easy enough.. can be scaled to numerous sizes. 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.