Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: freiberger mirrors (surface coated) repair/replace options
    From: Bill Morris
    Date: 2010 Apr 4, 13:15 -0700

    For re-silvering, or rather, re-aluminising, first port of call might be your local astronomical society, as nearly all amateur astronomical telescope mirrors are now aluminised and they would know who does it locally.

    You could try your friendly local glazier and ask him to cut second surface mirrors out of 4 mm float glass, which is quite flat enough for the purpose. There are two disadvantages to this: light loss due to reflection off the first surface(depends on angle of incidence) and on passing twice through the glass; and displacing the apparent position of the reflective surface backwards makes it slightly more difficult to correct perpendicularity error of the index mirror. The first is of little importance and the second largely theoretical and can be overcome by using sighting vanes, dominoes, hexagon nuts, precision cylinders or what-have-you at zero and 120 degrees, as shown in the attachment. These bring the line of sight up to the approximate axis of the telescope.

    On removing and replacing the clips, it is helful to sit at a table, wearing an apron with its skirt clipped to the table. That way, the clips and their tiny screws are less likely to escape on to the floor. When replacing, make sure the adjusting screws are slackened off. Put the screw through the clip and position it over the corner of the mirror/bracket. Push down on the coiled bit at about 45 degrees and after a little practice and a few false starts, you will be able to start the screw in its hole. It's a good idea to place a fleck of grease on its threads to try to prevent corrosion. The threads are necessarily fine ones and they have only the wall thickness of the mirror bracket on which to hold, so that very little corrosion results in stripped threads. Do not overtighten, of course.
    ----------------------------------------------------------------
    NavList message boards and member settings: www.fer3.com/NavList
    Members may optionally receive posts by email.
    To cancel email delivery, send a message to NoMail[at]fer3.com
    ----------------------------------------------------------------

    File:



       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site