Here we have the latest forge building class. My friend and previous student Max showed up for an intermediate class in tool making and forge building. We started out with a refresher on basic technique and hammer control. We then proceeded to work on building 2 axe head tools specific to Max’s business of cob construction and natural stone stove building.
Max had a design for this axe head that made it look like a small Polaski. That is an axe head on one end and a hoe on the other. However, rather than being as large as that fire tool, this one was about 10 inches overall. We started with a piece of 1 1/2″ by 3 inch solid square stock. We set up the piece to slit and drift open an eye for the handle. This required both Max and I to provide the team hammering technique to drive the slit chisel through both sides. We also decided to make two of these in case we were off with the slit chisel and screwed one up. Once we had the eye holes drifted out to the right diameter I sent Max -with some prior instruction- to work with the Little Giant to draw out the blades. There is a great feeling of accomplishment when one is able to create from scratch a workable tool. Go to our videos page and you can see a pretty satisfied Max at the power hammer.
On the second day of class we focused on building Max his own forge. This is where the student not only learns how to build a forge but makes their own to take with them. The photo at the top shows the materials needed. We were using mostly recycled materials. The burn chamber was part of an old air compressor tank, the feet left over angle iron and the air intake was a car exhaust pipe. We spent the better part of the morning running to the hardware store for the gas fittings and some smaller black pipe, then over to Harbison for our Kao-wool and fire brick, then back to the smithy and put them all together. We needed my forge to heat up the air/gas out flow pipe. This is where the mix enters the burn chamber. The 2 inch pipe is hammered or necked down to form a rectangle about 1/2 an inch wide for an opening.
Between heats we worked on the chamber. First was to weld on feet. Basically it consists of two pieces of angle iron welded on to either side to keep the chamber from rolling. Another advantage to using angle iron is that you can drill holes and weld on nuts so that bolts can be used as feet and for leveling.
Please note that if you begin to forge the air/gas mix out-flow pipe too fast you will crush or cave in the pipe too quickly. In the next picture Max needs to open the pipe at the orifice just a little.
Next up is cutting out the opening in the burn chamber to receive the mix pipe. This required the use of the plasma cutter. We placed the pipe at an angle so the when in use the air/gas flow will rotate around the inside of the chamber. Always tack weld the pipe first and check your angle.
Next up we drilled the exhaust pipe elbow for our gas pipe fitting. This is where the gas will mix with the air.
Our gas pipe consists of 1/2 inch black pipe 10 inches long. It is threaded on both ends and can be purchased at your local hardware store. On one end we placed a nipple cap. This cap has a 1/16th inch hole drilled on the end. The hole allows the gas to be compressed into a jet at the mix point.
The gas pipe is then placed in the exhaust elbow where the cap rests about an inch to two inches back from the opening. Note in the photo the hose clamp. This will allow you to connect and secure the mix pipe with the forge.Make sure you line up and center your gas line before welding.
The air/gas mix pipe can now be placed on the burn chamber. From this point on you will need to lay in you Kao-wool and set fire brick shorts inside for the floor. For the air system I use a $15.00 dollar hair dryer. If you choose this remember to disable the hot air switch so that the blower does not overheat and shut off. The blower is set at the bottom of the exhaust pipe and can be held fast with duck tape. For the gas line you will need some flexible steel pipe. The hardware store will have the one you need. They are sold for gas lines to dryers and gas stoves. A 5 gallon propane tank can be used but I use a 25 gallon tank. Remember, within the line from tank to forge you will need a stop cock for an on off switch and an adjustable regulator to “dumb” down the gas as it leaves the tank. For this forge you will need about 12 fire brick 3″ x 7″ or so needed for the doors and also 2 flats that are needed for the floor. I keep both ends available that way to either work from both ends at the same time or to be able to place longer pieces through. This forge will attain a forging heat of about 1800 to 1900 degrees.
If there are further questions on this model or you would like to take this class please write me here at the Smithy. Thanks to Max Edleson.