You Can Cast Iron
Old engines fascinate me. I love to restore old machines. Many machines are scrapped because of broken castings, or parts cost more than a working machine is worth. I knew of several machines that could be had for little more than the time spent to recover them…If only I could produce iron castings. After some research, I found that iron could be easily melted in a cheaply built shaft-furnace called a “cupola”. With this in mind, broken machines that had been junk, were now viable restoration projects.
Casting iron parts may seem complicated at first, but after a little practice, it comes quite easily. The casting process is briefly described in the following photos. The example in this case is a set of shoe anvils for my brother in-law’s shoeshine booth. Because the shoe anvil is a round part, it is split down the middle and held together with short dowels. Just as easily, I could have used a machine part; however seeing a split pattern is a good start.
One half of the pattern is set on a section of plywood called a molding board.
A flask holds the sand mold together. It is divided into a top section called a cope and a bottom section called a drag. Set the drag around the pattern. Dust the pattern and molding board with parting dust, which is a plastic powder used to make the pattern release from the sand. Set a “riddle” or screen over the flask and pattern and shovel some molding sand in. Work the sand through the screen to remove and trash or lumps. Carefully pack the sand around the pattern by hand so as to not jar the pattern out of place.
Ram the sand tightly around the pattern with a rubber mallet
When the mold is full, strike off or scrape the flask with a striking bar.
Repeat the process until the top surface is smooth and level. Set a bottom board over the mold and roll the whole thing over.
Lift the molding board off to expose the bottom half of the pattern in the sand.
The top half of the doweled pattern is set in place.
Dust the pattern with parting dust. In this case I am using an old sock to hold the parting dust.
The mold is filled and struck off like the bottom.
Cut a sprue and some risers in the mold by driving a short section of thin pipe through the sand with a hammer. Open the mold, remove the pattern, blow out the loose sand and cut a runner or trough for the molten metal to flow. (note: the photo shown is from a faceplate casting) Vent the mold by piercing the sand with a stiff wire.
The mold is closed and the flask is removed from the sand. Several finished molds are waiting to be poured.
Fire up the cupola and tap a ladle full of hot iron.
Pour the waiting molds, in this case a 58-pound lathe faceplate is being poured.
When the castings cool they are dug out of the sand. A fresh shoe anvil casting straight from the sand.
The runner is cut with a hand grinder and broken off with a hammer.
A few passes with a hand grinder and the casting is ready to be drilled and painted. Other castings poured that day included these head and tailstocks to be used on a small cam grinder, and the face plate.
Pouring iron is easier than you might think. Once you can produce castings, many good restoration projects are now available to you. New machines can be built from scratch. The possibilities are endless.
Never underestimate the importance of safety in a foundry. Metal is extremely hot and will spatter if spilled on a wet surface, (this includes concrete). Be sure to wear long pants and sleeves. Boots, goggles, a hat and face shield or welders mask. Good luck and happy casting.
Author: Steve Chastain
Steve’s web page – stephenchastain.com