Ep. 328: Telescope Making, Part 2: Serious Gear

Some astronomers are control freaks. It’s not enough to buy a telescope, they want to craft every part of the experience with their own hands. If you’re ready, and willing to get your hands dirty (and covered in glass dust), you can join thousands of amateur telescope makers and build your own telescope from scratch.

2 Responses to Ep. 328: Telescope Making, Part 2: Serious Gear

  1. Bob Blinn January 19, 2014 at 4:18 pm #

    Thank you so much for episode 328. To me, mirror grinding is based on a very old and universal principle of hand craftsmanship which was swept away by interchangeable parts and mass production. The principle is that parts will fit well if they are ground together. We can imagine how this might have been applied in many ways in pre-industrial eras. When two glass discs are ground together while constantly changing their relative rotational orientations, the only surfaces that can result will be two corresponding spherical surfaces that fit perfectly. The same is true for polishing, except, for polishing, the convex tool is surfaced with pitch to carry a polishing compound. The last step is to deform the near perfect, polished concave sphere into an aspeheric conic section, which for an amateur like me is usually a parabola. The difficulty of this parabolizing step increases inversely and geometrically with the selected focal length of the mirror. To me, the charm and wonder of amateur mirror making is that something so extremely precise, even within a few millionths of an inch, which has the power to bring to an observer astonishing cosmic wonders, can be fashioned from a crude chunk of glass (even a surplus maritime porthole glass) with nothing more than a pair of muscle powered human hands, some abrasives, a lump of pitch, a lamp, a pin hole, and a knife edge.

  2. AmyD. January 28, 2014 at 8:57 pm #

    I started grinding my own mirror a few years ago. It’s not done yet – I had to put it on hold for a few years due to illness. Hearing this podcast has re-inspired me to get it finished!
    Thank you!

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