Mechanical structure



The motor drive is very important in a photographic telescope. There should be no systematic errors or irregularities in movement. I was looking for an aluminium tube for my first telescope (Newton) in an ironmonger's shop situated in the province of Padova when I saw a wonderful pulley made of cast iron. Its diameter was 1m and its width was 15cm; it had a hub with a diameter of 25cm. It was suitable to a shaft of 15cm, which can support a telescope with a objective of 50cm. Five spokes with sturdy ribbings on them and a width of 2 cm joined the hub with the rim of the pulley, which had a thickness and a width of 5cm: wow! However there were 2 problems: some conical cogs that lained out 1.5 cm from the diameter of the rim and the weight of the pulley, which was more or less 70 kg. I didn't know what to do with the pulley: how could make it suitable for my telescope? Where could I find a lathe turner able to work it? I came back home with the aluminium tube for the Newton telescope but the pulley was still in my thoughts. I looked up "lathe for big diameters" in the yellow pages: fortunately there were 3 lathe turner not very far from my town. The next day I visited them all and I found a lathe able to work my pulley. I rushed to the ironmonger's shop: I was afraid I wouldn't find the pulley, but fortunately it was still there. I bought it and loaded it on the luggage-rack (the pulley was almost too big for it), then I took it to the turner. After a few days it was ready: the first step was done.

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