metal telescope mirror

I recall reading that Newton envented his own telescope, using a mirror which he made out of speculum metal. I would guess that he didn't have much available to him in the way of metal working equipment, so one thing I'd like to know is how he did it and how one can imitate his method. The other is how one might do it more easily in a modern home shop.

For example, can you do it with an ordinary metal lathe or would you really want to use a numerically controlled lathe? When the machining is done, would you have to do some kind of scraping or polishing of the mirror or would it be possible to use it as is?

Ignorantly, Allan Adler snipped-for-privacy@zurich.ai.mit.edu

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Reply to
Allan Adler
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If you just want to make a mirror, it's probably easier to make a glass one.

You can do this with just a thick bit of glass, some beach sand, some roofing tar, and little else to generate a near-perfect curve.

Adding a few small bags of various grades of abrasive, some polish, and a few other inexpensive items makes it quite possible to do without any other tools.

Reply to
Ian Stirling

Reply to
Machineman

Actually, making mirrors is done by hand. Not even a lathe is used in the work on the metal. There are a number of sites on the web where mirror making is described and my site

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is one where things are described. Working with metal is just like working with glass. The construction of reflecting telescopes was a great step forward with the astronomical community as the possibility of short focus widefield large scopes became possible.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

Reply to
Bob May

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