From Fran: Aldrich has received a donation of 24 Pyrex© mirror blanks from United Lens company in Southbridge, MA. We are very grateful for this donation and plan to make them available at no cost to Aldrich club members who commit to finishing a mirror in our mirror workshop, and constructing a telescope using the finished mirror.
Steve & Fran (club ATM mentor) discuss mirror making
The mirror blanks are precision annealed, 8.375 inches in diameter, conical in shape, and pre-molded to ~f/6.7 focal ratio. They can be used to make any reasonable focal ratio equal to ~f/10 or lower. A good description of this type of mirror can be seen at the Robert Royce website
. These mirrors are lightweight, and equalize thermally with the ambient temperature more quickly than the standard mirror blanks which are more massive. In addition, they can be easily mounted in homemade mirror cells, reducing mirror cell costs considerably (see mounting ideas
These blanks will be available for the next Aldrich Mirror workshop which will run from September 2016 to the holidays this year. We estimate any Aldrich member should be able to finish a high quality 8.25 inch telescope for less than $400.00. Given that the blanks are pre-molded to approximately f/6.7, most of the grinding time that would normally be required is eliminated. One club member recently finished an f/5.5 mirror using one of these blanks in one long weekend, and the mirror figure tested perfect by two expert mirror makers in an autocollimator.Aldrich club membership is required to participate in this program. For more information, or if you wish to join the upcoming workshop, contact Fran Edwards at email@example.com
United Lens celebrates 100 years
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