Instructor Richard Sanchez shows student Charles Howard molding techniques.
Photos by Larry Angier & Carolyn Fox
Every collector likes to get inside his engine. There's no such thing as too much grease, rust, dirt or expense. Machining a part to its exact specs gives a special sense of accomplishment in the finished product.
Now for the truly adventuresome hands-on restorer there's the opportunity for the ultimate do-it-yourself project casting an original part by pouring molten iron into a sand mold formed by your own hands. The place where all this happens is Historic Knight Foundry in Sutter Creek, California.
The foundry is housed in a big old weathered rough-timbered building at the end of Eureka Street. The interior carries the scars of a 1936 fire as well as past glory. Today, as in the past, gravity flow water from the Mokelumne River enters the building, rotating the water wheels and setting an elaborate, precisely balanced system of belts and pulleys into quiet motion.
The central machine shop is powered by a 42' Knight turbine. Large machine tools are powered by individual Knight water motors. Many of the machine tools were produced on site. There are several lathes up to 10 feet in diameter, a 7 foot radial drill and a 16 foot planer. Other pieces were carried by sailing ship around the Horn to San Francisco and brought overland by wagon.
Established in 1873 at the height of the California Gold Rush, Knight Foundry supplied heavy mining equipment as men dug ever deeper in search of the precious metal. Now the only water powered foundry and machine shop in the country, Knight Foundry was in continuous operation until its closing in 1989. Brought back to life in 1991 by Ed Arata and his partner Robin Peters, the foundry continues to pour special order castings, fill commercial orders and, perhaps most importantly, serves as an educational center for 19th century casting skills. Emphasis on education is not new. For much of its history, Knight Foundry produced the best trained and most highly respected journeymen in the industry.
One of those 1880s machinists was Ed Arata's grandfather. Born in Sutter Creek, Ed has traveled around the world, and is now resettled in his hometown, dedicated to preserving Knight Foundry and the art of sand casting.
Intimate living history three-day workshops take each participant step-by-step from pattern making to mold making, pouring and finishing. Each step requires making decisions, taking chances and working with natural material. Students can have as much hands-on experience as desired, and there's always an instructor nearby to get the participant out of whatever jam he's gotten himself into.
Everything begins in the pattern shop where mechanical drawings assume a life in wood. Knight prefers to use seven-year-old sugar pine. The wooden pattern must be carved slightly larger than the desired size of the finished piece, allowing for a 2% shrinkage when the molten iron cools.
An alternative to the wooden mold is using the original piece the restorer wishes duplicated. However, in this approach, proper preparation of the original is essential. Dimensions must be increased by the use of a filler agent, and the piece must be absolutely smooth and properly beveled. Without the proper angle it's impossible to remove the piece from the sand mold.
Cores made from a mixture of sand and resin are shaped and integrated with the pattern to achieve the open interior areas that are often necessary in a finished piece of cast iron. When iron is poured into the mold, the core keeps molten iron from filling that space. Next the pattern and cores are placed in a wooden flask and surrounded by a molding mixture of silica sand, ebonite clay and carbon. Properly prepared, the sand mold offers a perfect reverse image of the finished piece. After the pattern is removed, the mold cavity is ready for the pour.
The pour is the high point of all foundry work. Recycled scrap iron is heated with coke for several hours in a huge cupola furnace. An array of sparks fly from the opening as a blast of air shot into the furnace increases the intensity of the melt. This causes the fire in the cupola to thunder with such intensity that it vibrates the hillside around the foundry.
After cooling, the finished casting is pulled from the mold either by manpower or crane. The piece is then machined and finished to final tolerance.
If this sounds a bit ambitious for you personally, Knight Foundry is willing, capable and eager to supply you with finished reproduction pieces. Some workshop attendees have done both.
Gas Engine Magazine reader Lauren Langdon of Buhl, Idaho, has attended several sessions, making some parts himself and leaving others to the experts.
Lauren says, 'It's real exhilarating. There's nothing like being right there with your hands on the ladle pouring. You can see the problems the men had back then. The water powered, belt driven equipment is something to see. You can't find it anyplace else. Of all the things I did in 1993, this was the most rewarding. I'm going back.'
Several workshops are held throughout the year. Along with a unique experience, you'll come away with new friends and perhaps a deeper appreciation of iron history and the men who worked the industry. You'll no doubt add new words to your vocabulary. The terms parting powder, flex and drag and sea coal will start coming up in your conversation.
For the less adventuresome, the Foundry is open for self-guided walking tours, offering up-close views of the experts working their trade.
For information contact Ed Arata, Historic Knight & Co., PO Box 158, Sutter Creek, California 95685, phone 209-267-5543.