Amateur Telescope Making Main Page

Introduction

A lot has changed since Russell Porter wrote those
words – today the “average workman” can afford to buy an already
made telescope and Dobsonian mountings are very popular.  Much
is also unchanged – mirror grinding techniques are very similar to
those written up by Porter and Ingalls in the 20´s and 30´s. Many
amateur astronomers still choose to fabricate their own instruments,
for the pride of accomplishment, the gaining of knowledge and the
insurance of quality. Telescope making is at the heart of the
Springfield Telescope Makers – after all it is two thirds of our
club’s name – and on these pages we hope to show you that you too
can make your own telescope – and it can be an excellent performer!

A note on ATM techniques: There are almost as many ways to
make mirrors and telescopes as there are telescope makers. On these
pages we present one or more ways that have worked for us, but that
doesn’t mean there aren’t many other valid approaches. In fact, many
of us enjoy ATMing because we can experiment with different
techniques and sometimes find better ways of making or building a
telescope. And even if our new technique isn’t better, we usually
learn something valuable in the process. On these pages, however, we
have tried to stick with simple and proven techniques that are most
appropriate for novice mirror and telescope makers, and are
generally what we teach beginners at the
Stellafane Mirror Class.

Amateur Telescope
Making Table of Contents

General Information

• Selecting a
  Telescope

  Provides basic information about telescope for beginners, and
  briefly discusses important factors that should be considered in
  Selecting a First Telescope.

  • Are You Ready for
    a Telescope?
  • Objective
    Size is Important
  • Types of
    Telescopes
  • Types of Mounts
  • Portability
  • Make or Buy?
  • Why Newtonian
    Reflectors on Dobsonian Mounts are a Good First Scope
  • Selecting Mirror
    Size and Focal Length

• Mirror Making Myths
  & Information for the Curious

  There are a lot of misconceptions about making a mirror –
  read this even if you don’t plan to make a mirror, but just want
  to know how it is done – with your bare hands and a few
  simple tools, you can grind and figure a fine mirror with a
  surface accurate to a few millionths of an inch!

• Telescope
  Formulas and Design Comparator

  This page has formulas for many telescope and mirror
  parameters. It will calculate parameters for two different
  telescope designs and compare the results for you. It provides
  data to help in selecting a telescope, and also provides
  information necessary for mirror making and testing.

Telescope Mirror Making

• Overview
  of Mirror Making

  Pyrex Mirror Blanks

• 
  Materials and Tools

  • 
    The Mirror Blank

  • 
    The Tools: Grinding & Polishing

  • 
    Grits & Pitch

  • 
    Grinding Stand: Barrel, Stand or Turntable

    • 
      Build an ASGH Wooden Barrel

  • 
    Storage Containers: Mirror, Pitch Lap & Grit

  • 
    Miscellaneous

• Grinding

  • Making a
    Tile Tool

    • Making a
      Plaster Disk
    • Tile Tool
      Problems – What to do

  • Selecting a
    Surface to Grind

  • Beveling
    the Edges

  • Rough
    Grinding

    • 
      What is a Wet?

  • Fine Grinding

    • When to
      Switch Grits
    • About Scratches
    • The Pencil
      Test – checking for “Good Contact”

    Polishing in the McGregor Observatory

  • Measuring
    Sagitta

• Polishing

  • Pouring a
    Pitch Lap

    • Making a Plaster
      Disk
    • 
      Removing an Old Lap

  • Lap Maintenance

    • 
      Hot & Cold Pressing
    • 
      Trimming Channels & Edges
    • A
      Heated Electric Channel Cutter
    • 
      Brushing a Glazed Lap
    • 
      A Pitch Hardness Tester
    • 
      How to Store Your Lap
    • Using Old
      Pitch

  • Polishing

    • When is my
      Mirror Polished Out?
    • Temperature
      & Humidity Considerations
    • About
      Turned Down Edge
    • About
      Polishing Pads

• Figuring

  • Introduction to Figuring
    A Change of Pace

  • Figuring to a Sphere

  • Figuring to a Parabola

• Mirror
  Coatings
  Aluminizing, Silvering & Enhanced
  Coatings

• Mirror Making References & Calculators

  • 
    Telescope Formulas and Design Comparator

  • 
    Sagitta to Focal Length Calculator

  • Guide to
    Grit, Polish & Pitch

    • Grit: Material,
      Sizes
      • 
        Grit Size Table
    • 
      Polishing Compounds
      • 
        How to Mix Cerium Oxide
    • Pitch
    • How much
      Grit, Pitch & Polishing Compound will be Needed?
    • 
      Safe Handling & Storage

  • Guide to Strokes

    (includes many short videos)

  • How to Clean a Coated Mirror

Optical Testing

Cody Tests his Mirror

• Testing
  Overview

  Why we advocate using both Ronchi &
  Foucault Tests.
  Video that reviews all
  common amateur test techniques.

• Basic Testing Knowledge

  • 
    Reading Ronchigrams
    • Selecting a
      Ronchi Grating
  • Understanding Foucault
    Testing
  • Reading Shadowgrams
  • Measuring
    Parabolas

• Mirror
  Quality

  How good is Good Enough?

  • 
    Polish Quality
  • 
    Surface Quality
  • 
    Figure Quality

• Practical Testing

  • Setting up your Tester

  • Testing for a Sphere with a Good Edge

  • Testing for a Parabola

  • Auto-Collimation Testing

  • Telescope System Tests

    • The Star Test
    • The Ronchi Test

• Building
  Mirror Test Equipment

  The Stellafane Tester

  Complete plans for all the test equipment you need to
  accurately test and figure your mirror.

  • Build a Foucault / Ronchi / Knife-Edge
    Tester

    • Page 1: Base & Stage
    • Page 2: Head & Setup
      Aids
    • Page 3: Electrical
    • Page 4: After Thoughts
    • Page 5: Parts
      Reference

  • Build
    an Adjustable Mirror Test Stand

  • Make a Couder
    Mask and Everest Pin Stick

  • Calculate
    Mirror Zones

    to make a Mask or Pin Stick for your mirror.

  • Print a Ronchi Screen

    on your Inkjet or Laser Printer

• Foucault Data
  Reduction Software

Our Dobsonian Telescope

Build a Dobsonian
Telescope

Plans for building a Newtonian Optical Tube and a Dobsonian
Mount for 4 to 12 inch telescopes.

Complete step-by-step instructions for both the optical tube
and Dobsonian mount.

ATM Resources & References

• Books &
  Periodicals

  Information about the publications we use to develop or check
  the information on these pages.

• Internet Resources on our
  Links Page

  • ATM Web
    Pages

    Hundreds of links to all aspects of telescope making on
    the internet.

  • ATM Material Suppliers

    US suppliers of Mirror Blanks, Grinding & Polishing
    Supplies, and Telescope Making Supplies.

  • Astronomy Clubs

    Many can offer help with your project.

  • 
    Astronomy Conventions & Star Parties

    A good place to look at various telescopes and chat with
    their owners.

• Mirror Making
  Courses & Workshops

  A world-wide list of Mirror Making Courses we know about,
  part of our Mirror Class section.