Noobie Posted March 1, 2008 Share Posted March 1, 2008 Well, I've been visiting websites for years wanting to setup a forge and start pounding some metal . Now that I actually can, and have a basically limitless supply of metal on hand for free or minimal I want to start designing a forge and building it. Now, I've just recently started a new job at a steel mill, They use natural gas for everything, from the reheat furnace to the cutting torches, So I know it can easily get hot enough to work steel with, Any particular advantages between natural gas and propane? And what kind of blower system should I look into? I've looked at several of the gas forge designs on the site, And I will use similar ignition and fuel injection systems, But not much was said about Blowers. I've been thinking of making the forge out of an old acetylene tank, one of the big fat round ones Any, pros/cons on that one? And of course since I cant afford to do everything at once I will probably be using part of a steel slab from work as an anvil, we ship everything from electrical steel to armor plate so I'm sure something will work. And I can easily cut down and bevel any said chunk of steel into something workable I should think, the machine shop guys shouldnt have a problem with that. Anyway, more information is always welcome. Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted March 1, 2008 Share Posted March 1, 2008 I personally would find another container other than a Acet tank they are full of a material to reduce hazard and residual gases may ignite or blow up when you cut it. I have not used natural gas but I think there is a problem with gas delivered for home use as it is low pressure and may not operate a gs forge. At the lest look into the area a bit...have fun Quote Link to comment Share on other sites More sharing options...
Jmercier Posted March 1, 2008 Share Posted March 1, 2008 The issue with natural gas is that the supply lines to your home are not usual high enough pressure for most of the purposes needed for forging and other shop jobs. Usually it's rather expensive to get the proper high pressure service you'd need for forging. Quote Link to comment Share on other sites More sharing options...
Glenn Posted March 1, 2008 Share Posted March 1, 2008 Read Rich's warning about the acetylene container. There are other items out there that are a lot safer to use. Quote Link to comment Share on other sites More sharing options...
Noobie Posted March 1, 2008 Author Share Posted March 1, 2008 the acetylene tank would be cleaned out first.. it starts to blow at pretty low pressure and temps, plus has acetone in it to stabilize the acetylene. And cottonlike stuffing, but oh well. Alright, I'll look more closely at propane then, Thanks all. Quote Link to comment Share on other sites More sharing options...
Jymm Hoffman Posted March 1, 2008 Share Posted March 1, 2008 Just a quick reply as I head out to my shop for the day. I have been using blown forges since 1993, with low pressure propane. The systems have evolved out of Johnson Furnaces. Many industries use Johnson style furnaces on natural gas, at house hold pressure and higher pressure blowers. These are very inefficient and slow to heat up. Mine on the other use about 1/2 gallon of propane an hour on the 2 burner to 3/4 to a gallon on a 3 burner, depending on the size of the forge. I buy blowers from Kayne & Son that work great for my smaller every day use systems. While I use propane and have not tried my system on natural gas, they should work just fine. They are not as complicated to build as naturally aspirated systems. One trick is having a higher pressure blower. Now to the size of your system. Too many people want to build industrial size forge/furnaces when they only need something much smaller. How much metal can you pound on at one time? Unless you are heat treating very long pieces, bending very long pieces, or have a large power hammer with a crane, I would recommend starting with a shell that is no more than 12 inches long and 12 inches wide. I have used old 20 pound propane tanks with great success and made a living using these. I do have a larger one for larger scale work. These are lined with 2 inches of ceramic fiber blanket and a layer of ram refractory on the bottom to protect the blanket and it helps the way the system works. I will post some more information later. Off to pay the rent and taxes. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 3, 2008 Share Posted March 3, 2008 SOFA had a propane forge workshop where we made forges from scrapped Oxy, N2, Ar, etc tanks. The tank test place *gave* us the tanks but required we cut them in two on site---they even gave us the gas to do so we had to bring our own torches. Makes for a heavy forge, good for somethings, bad for others. I welded a sq tube on the side for a third hand and the weight will hold most of the stuff I work with. The shell of most gassers is rather trivial---it's just to hold the kaowool in place. I have seen one professional smith that needed a large forge for 1 job and just tied a roll of kaowool up with binding wire and stuck the burners in that. Acetylene tanks are durn hard to demil, the stuff inside can even be asbestos, theough modern tanks use diatamacious earth in them. residual acetylene and acetone can be toxic/explosive, etc. if you just want a bigger tank get a scrapped old propane tank from a propane dealer and using proper technigue clean it out and use that. Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 3, 2008 Share Posted March 3, 2008 I agree, an old acet tank is more hassle than it's worth even if you ignore potential danger. As an example for a student of mine who was looking for the PERFECT piece of pipe for his forge before he started building I used hardware cloth to make the shell and a double wrap of Kaowool with a firebrick laid on the bottom. The forge ws up and running in about five minutes. I don't recommend allowing the Kaowool direct contact with air as there is some hazard from silicosis from airborn particles. What I like for pipe forge shells is SS stove pipe. It's light, plenty strong unless you're going to forge some real heavy weight stuff and it's workable with hand tools, no welding necessary. If you use off the shelf sizes you can use other fittings to make the build even easier. Wall brackets for example make perfect legs. If you want an oddball size you can put different size pipe together to make them. For instance a piece of 6" and a piece of 8" snapped together along their seams makes 14" dia. SS is a poor conductor as well so at least some heat is reflected back into the forge and the more heat you keep inside the less fuel you need to keep it hot. Every little bit counts as long as it isn't a major hassle. Frosty Quote Link to comment Share on other sites More sharing options...
Dave M Posted March 4, 2008 Share Posted March 4, 2008 I have a bunch of different gasser forge bodies. The first 1 I bought at the auto parts store or wally world it is 1 of those red spare air tanks 10 gal. $19.95 worked great and is still in use after 4 years. The rest I got at the dump, a bunch of different sized portable air compressor tanks and for small forges I picked empty party store disposable heluim tanks. On some of the bigger compressor tanks I have cut the dished ends off and used each end to make 2 coal forges and then used the main body of the tank for propane forge or to make fire pits for camping. Heck I pick up as much as I can from the dump, my ride on mower & walk behind mower & 2 snow blowers & table saw & tiller + chain saws and weed wackers. I have only had to buy new plugs then clean out and put fresh gas in all of these, oh who ever owned the table saw put the blade on backwards.:o Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 5, 2008 Share Posted March 5, 2008 & table saw I have only had to buy new plugs then clean out and put fresh gas in all of these, oh who ever owned the table saw put the blade on backwards. Gass powered table saw? Cool I thought only people in AK had such things. :cool: Frosty Quote Link to comment Share on other sites More sharing options...
Johannes Posted March 5, 2008 Share Posted March 5, 2008 Cant you just avoit the potential danger by filling it up wit water and then cutting it with a grinder..? thats what I did with an old propane cylinder, worked wonderfully. Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted March 5, 2008 Share Posted March 5, 2008 The issue with natural gas is that the supply lines to your home are not usual high enough pressure for most of the purposes needed for forging and other shop jobs. Usually it's rather expensive to get the proper high pressure service you'd need for forging. I've a good friend that uses natural gas and he makes cable and patteren welded knives with no proble. He made his forge from a large oxy cyl. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 5, 2008 Share Posted March 5, 2008 An acetylene tank is already full, you can't add water to it. It contains a filling (asbestos, diatamaceous earth, etc) that is soaked with acetone and the acetylene is dissolved into that. Acetylene can explode even without the presence of air. Acetylene can explode when pressures get above 15 psi. Acetylene can explode if the freespace containing it is large enough---why dinged tanks are discarded, the damage may have opened a void. DON"T MESS WITH ACTEYLENE TANKS! As was mentioned you can fill other types of pressurized gas tanks with water and make a safe if messy way to cut them up. Do not use a cutting torch to cut empty thinwall tanks as unburnt acetylene and O2 can build up to reach explosive concentration and you then find yourself holding a torch on a BOMB---lots of deaths each year from folks doing this to 55 gal steel drums. (Thick wall tanks can go boom too but you are less likely to have sheet metal shrapnel sleeting though your body Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted August 1, 2009 Share Posted August 1, 2009 (edited) Using a steel blade backward (NOT CARBIDE) is an old trick for cutting corrugated roofing and other light sheet. It hammers out a slot. Works rather well in a table saw or skill saw. Oh yeah, I've run quite large forges on domestic low pressure gas, no problem. Edited August 1, 2009 by nakedanvil Quote Link to comment Share on other sites More sharing options...
Muttt Posted September 5, 2009 Share Posted September 5, 2009 (edited) I saw some really cheezy really simply built gas forges that can easily get to weld temps. I didn't want to mess around with venturi's so I made mine with a blower. I got an 11 inch wide piece of water pipe from an aircraft carrier from the local scrap yard. It's about 18 inches deep. I welded a circular plate over the back end and torched a 1 1/2 inch hole in it so I can stick a long knife for sword out the back while heating. I torched another 1 1/2 inch hole on one side and welded a 1 1/2 inch pipe coupler to the side. Then, I screwed a 6 inch long piece of pipe into that and added a gas valve on the elbow. I then attached another pipe to the elbow and I use a shop vac on reverse for a simple blower. I use an extension cord with a dimmer switch to control the air speed. I had a local propane shop make me an adapter so I can just screw on one of the hosed I use for my grill when camping. I use a 5 gallon propane tank. I lined the inside of the pipe with kaowool and laid two hard fire bricks in the bottom for a sacrificial surface because using flux eats the wool. The whole thing is really simple and easy to use. If I need more heat, I put a small piece of fire brick in the opening to choke it down a little and increase the heat inside. Easy to build, all parts can be bought at home depot and a camping store or propane store. The Kaowool and fire bricks can be bought at a clay/kiln supply store. Here is a pic of my forge with only one layer of kaowool and a soft fire brick out front for a shelf to set your work on ........ Here is another pic of my forge with the second layer of wool and a brick in the opening........... Here is a pic of it fired up ....... you can see the gas valve and the shop vac hose. I leave the forge in the weather. I can just detach the shop vac and take it inside when it rains........ Hope some of this helps. There is no need to dump tons of money on burners and all that. Some of the simplest things work great forges and it doesn't need to be "over engineered". You can see where my pipe is welded to the side of the forge and the six inch pipe ...... that is my burner. Simple and easy to replace ..... unscrew it and get a new one from home depot. Here is a pic of the a really simple design that I based my forge off of. This one is really small so I super sized mine a little ...... Mutt Edited September 5, 2009 by Muttt Edited due to wrong picture ..... replace with proper one Quote Link to comment Share on other sites More sharing options...
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