Good Old Wood

Jack Kramer

Check out the construction of any number of telescopes, and you're likely to see a lot of wood being used as a main ingredient. Even commercial manufacturers often provide wooden tripods. Apart from the fact that wood is the most readily available and easily-worked material, there's a good reason for using lots of it. Wood has superior dampening characteristics. This means that vibrations settle out more quickly in wood than in metal of comparable mass. A number of years ago, I wanted to rework my telescope mounting, and as luck would have it, another member of the club offered to give me his old German equatorial mounting. He's a tool and die maker and had done a beautiful job of machining this mounting and pedestal of heavy-gauge aluminum. After making a new saddle to mount the scope, I couldn't wait to try out my prize. But upon aiming the scope at an object in the night sky, I found that the mounting was like a giant tuning fork. The vibrations took forever to dampen out. Despite various stiffening measures, the mounting never did prove satisfactory, and I ultimately refabricated the base of the mounting primarily of wood.

While on the subject, it should be noted that one of the problems afflicting department store telescopes is unstable mountings and tripods. While the most expensive ones have passable equatorial mountings, the wooden tripods are flimsy. But didn't we just say that wood is a good material? Sure. But when the department store telescopes are advertised with "hardwood tripods", don't you believe it. Invariably they come with tripods made of a soft wood that isn't nearly stiff enough. (They don't have a lot of hardwood in countries like Taiwan.) Add to this the fact that the tripod is braced with metal struts connected with hinges to the legs of the tripod. This design might be okay if the legs were truly made of hardwood, but as it is, the hinges have too much slop to provide any added stability. Then they add soft rubber "anti-skid" tips to the feet of the tripod that...make it more jiggly!