Saturday, October 25, 2014

Homemade Knives (124 Pics)

Charcoal is the fuel, the heat source and the source of carbon for the smelter. Charcoal has to be chopped to a specific size for the operation to run smoothly. The bore of the furnace is 11 inches so that seems to be the right size for the charcoal: 8-10% of the inner diameter of the furnace.

The ore is from a ceramic supply place. The name of this particular compound is Spanish Red. It is a light dust that stains everything almost permanently red and contains 80% hematite.

The furnace design is based on the shell of a water heater. It has been cut in three sections for easier assembly and dis assembly. Here is a diagram.

The parts were cast with refractory made mostly of sand and cement with an inner lining of high temperature furnace cement. It held up pretty well to the heat but crumbled at the time of taking it apart.

The tuyeres were made of simple black iron pipe fittings. They stayed cool by the constant air flow through them and since they don’t protrude in the inner chamber they don’t become melted away.

Here is an additional picture of the bottom part of the assembly after pouring the refractory and letting it dry. It is shaped like a funnel as in the Japanese tatara

View of the assembled parts halfway through the construction

Covered the smelter in refractory blanket to increase the thermal efficiency. That actually worked really well. The temperature measured at the bottom of the top third of the smelter reads 1000 degrees F.

Home made manometer to gauge the air flow pressure. The manometer was indirectly reading the amount of air flow very accurately. The air flow was kept at about 15%.

Here it is running on charcoal now and with the first charge in. The temperature reads 1800 degrees F and it remained there or above for most part of the run. Charges started at 1/2 kilogram of ore and went up to 1.25 kilograms halfway through the run. Using about 2 kilograms of charcoal per charge.

The manometer is indicating the change in pressure during the run.

Bubbling at the tuyeres. Now taping the arches and keeping the tuyeres open and trying to keep up with the schedule of charges.

Even at this point 2 hours into the run there are lots of sparks coming out of the tap arches.

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