On Saturday, May 19th, 36 members attended an all day workshop at the Willard House Clock Museum in Grafton, MA. This is part of Chapter 8's strong educational program. All three speakers are Chapter members and experts in their own fields.
John Losch presented his views on Lubrication-One man's method. He gave some history of early lubrication with the materials available at that time. He pointed out that you lubricate for two reasons - reduce friction and prevent corrosion. For friction, any sliding surfaces under load and any arbor that rotates 360 degrees. Detents, warning - pins, hammer pins, clicks, click springs, crutch, verge, and mainsprings are usually oiled. Levers and chime hammers are examples of parts that fall by their own weight and are not lubricated. And leave the fan, fan spring and arbor alone-just the pivots. John indicated he preferred to test a repaired clock before lubricating. This way, oiling does not mask problems.
John showed some different types of oilers, but he prefers to use simple ones made by hammering brass or metal rods into small spaded ends for dipping into the oil. For mainsprings he uses a paste or artist's brush to get between the leaves. Oil sparingly, with oil sink just ½ to ¾ full. If you fill the sink, the oil will run down the plate and leave the pivot dry. If he overfills a sink, he uses tweezers with tiny dental cotton points to remove the excess oil.
There were many questions up to this point, which John answered, and then he gave his preferences for what lubricants to use. He feels that the companies that make clock and watch lubricants know what they are doing-so use their products. With one exception, he does not use automotive or synthetic machine oils on most clocks. Automotive oils have many additives and detergents that cause metal to rust. For mainsprings, Losch prefers an automotive 90 weight EP, and Vaseline for extra heavy springs. He left the audience with an interesting observation. Synthetic oil will probably provide longer running, but in doing so this masks possible dirt accumulations that could turn the pivots into great paste grinding machines!
Pendulums, Plain and Compensated was a talk given by Richard Ketchen. He brought with him about a dozen large and unusual pendulums to highlight his talk. Ketchen said that although Galileo was the first to suggest a pendulum, it was Christian Huygens in 1656 who gets the credit for putting one on a clock. These were not isochronous, and were subject to circular error and changes due to temperature. George Graham made a compensating pendulum by using mercury in a jar to raise the center of gravity with rising temperatures. This compensated for the lengthening of the pendulum rod. It is the center of gravity of the pendulum bob and rod assembly that determines the length for timing, not the weight of the bob itself. In 1726 John Harrison, brought out the gridiron of brass and steel to compensate on his clocks for use on ships. And finally we have Invar for making pendulum rods.. This is a modern metal that has no coefficient of expansion. And with a bob fastened to the rod in its center, expansion is equal both up and down. Richard then showed a gridiron pendulum that he made. It was a work of art and machining skill. There were many questions about the types of pendulums members came across and the theory behind them.
After a pleasant picnic lunch, Margaret Rodgers gave a very unique presentation on Bronze Powder Stenciling. Instead of just giving a lecture on how to stencil with powders, she had developed a hands-on program for the group. Everyone participated in actually doing a stencil. With a tremendous amount of planning, Rodgers prepared simple stencils and kits of paper, tape, ultra suede, bronzing powders and a prepared black strip of DuragloTM, which was still tacky with varnish as a base for bronzing.
Rodgers, a member of the Historical Society of Early American Decoration, first gave a brief history of the ancient art of stenciling, which goes back to the Egyptians. Later, in England, bronze powder stenciling became popular as a replacement for gold leaf, which was expensive as well as time and labor intensive, as a form of decoration on trays, furniture, clocks, and reverse painting on glass. Bronze powder stenciling offered a faster and more convenient method of decoration. She then explained what she wanted to accomplish and how the participants were to proceed. The objective was a splat for a clock top which was to be decorated on the Duraglo surface. This cardboard-like material, when varnished, leaves an example for the artist to follow for future work. The participants first made a master tracing on a paper with a pen from a design provided with the notes she passed out. Then one of the stencils was placed on the Duraglo and bronzing powder applied with the finger wrapped in suede. Additional stencils were then placed and bronzed to complete the pattern.
The results were interesting. A few potential artists emerged from the group and others gained a deeper appreciation for what those decorators and restorers do who work on their clocks! It was fascinating to watch Margaret handle a large group like ours and see to it that all were able to carry out her instructions to varying degrees. Her expertise and planning preparation was nicely demonstrated. She left the group with a detailed set of instructions for further homework if they so desired.