Paul McNabb founded the mirror lab in 1997 in order to create the best amateur telecopes possible. Inch for inch our mirrors surpass store bought or commercial grade scopes.

Part of the Saint Petersburg Astronomy Club Home of the 2017 OBS Star Party

Lab Members

Ralph Craig is a lab instructor and has made mirrors from 6 inches to his recently completed 16 inch f5 mirror.

Allen Maroney
has completed three mirrors in the lab between 8 and 18 inches. Allen is also buiding a second robo foucault tester based on James design.

Mike Davis
casts his own mirror blanks.

Irv Nadelhaft

Charlie Mullen ground the mirrors for two years worth of rafflescopes but now has moved on the clear skys of New Mexico.

Lab T-Shirts Available

Lab Alumni

Lenny Remetta

Keevy McAlavy

Bruce Kazcmarik

James Lerch built our robo foucault tester and in house aluminizing chamber as well as a laser interferometry testing setup.

Ron Jones AKA the figurer is about the best mirror maker this side of the mississippi. You can see things in his 8 inch mirror that would impress a takahashi devotee.


Russell W. Porter father of amateur astronomy and founder of Stellafane

Mel Bartels Website
Amateur Astronomer and innovator.

Stardate Website
Good overall observation site.

NGC Astronomers
Former member Matt Terry has his own astronomy club north of Tampa.

Southwest Florida
Astronomical Society

A nearby Astronomy club.

Telescope Software
Ray tracing program for determining all required dimensions for a newtonian reflector. (New Website)

Program for designing mirror cells.

Observing Software
3-D interactive simulation of the solar system and beyond.

Plots the jovian satellites.

Lunar Phase
Shows all the phases of the move and more.

Mirror Lab Home Mirror Making Supplies Robo Foucault Tester Telescope Gallery SPAC Library
Supplies List
Plans, Instructions, Software and More Information
Mirror Making Class

Supplies List

Blanks can be purchased from the following companies:

  • Willmann-Bell, Inc.
    (804)320-7016, about 5 days for delivery.
    You can now order mirror blanks direct from their website.

  • ASM Products Reg"d Canada
    BVC Black vitrified ceramic blanks
    (514)898-3990, About 6 to 8 weeks for delivery.

  • Newport Glass Works, Ltd.
    (714)642-9980, allow 10 to 14 days.

  • United Lens Co., Inc.
    259 Worcester St.
    Southbridge, MA 01550-1325
    (508) 765-5421

  • Grit

  • Ocean State Abrasives
  • Ebony Star Formica

  • C&R Decorative Surfaces
    727 328-8669
  • ScopeStuff has precut ebony star strips They also have small precut pieces of teflon too.
  • Tubes

  • Tampa Tube went out of business in 2007
  • CMC Construction Services Sonotubes
      AKA Shepler's   1201 North 34th Street
      Tampa, FL 33605
      (813) 248-5959
  • Weather Stripping

  • American Discount Marine
    6000 66th Street N
    St Petersburg, FL 33709
    727 546-8484
    ($0.85/ per foot)
  • Plaques

  • All American Trophy Works
    6240 39th Street N Ste B
    Pinellas Park, FL 33781
    727 525-6880
    ($20 for a nice plaque to put on your
    scope with specs and a nice mirror
    lab logo)
  • Woodcraft

    18891 US Hwy 19 North
    Clearwater, FL 33764
    Phone: 727-532-6888
  • Coating

  • Club members offer Aluminum only coating at $5/inch. Bring your mirror by the lab on Saturday and we"ll coat it and return it to you on a following Saturday.

  • Spectrum Coatings

  • Plans, Instructions, Software and More Information
    Portable Grinding Table schematic (pdf format)
    Allen Maroney came up with this nice set of plans for a portable grinding table. Its a three legged design with a flip top grinding platform. It's very stable and colapses down flat for transportation.

    'RoboFoucault' Mirror Testing Software
    There are two programs needed to test mirrors. The first images and scans the mirror. The second analyses the results and provides wavefront errors, strehl ratios etc...
    Real Time Automated Foucault Tester RTAFT (1.6MB)
    FigureXP (4.2MB)
    Dave Bevels RoboFoucault page
    Sagitta Calculation Sheet (pdf format)
    Online Sagitta to Focal Length Calculator
    How to paint the inside of a tube
    Paul McNabb created a very simple gizmo to help spray paint the inside of a cardboard tube. He was helping Art with his dobsonian tube and decided he was tired of getting covered in black paint every time the inside of a tube had to be sprayed.
    Dobsonian Equitorial Platform
    Lab member Paul Kristle has built a motorized platform that will allow dobsonian style scopes to be able to track like equitorial mounts. The platform was demonstated and tested on the 2003 rafflescope.
    How to Pack your Mirror for Shipping
    Shipping off your finished masterpiece for coating is a little scarry especially if it isn't packed right. Here are instructions with pictures for how to make a very good mirror shipping box.

    Mirror Making Class

    • Ever think of making your own mirror?
    • Want the best possible images from your scope?
    • St Pete Astronomy Club Mirror Lab can help.
    The Tampa Bay area isn't known for it's good clear skys. We have clouds, rain, haze and humidity to deal with in addition to light polution. As a result we have to make our mirrors better.

    For several years the Tampa Bay Mirror Lab has helped young and old learn the art and science of newtonian reflector mirror making. We can show you what we do and how easy it is for you to start making your own optical masterpiece.

    The mirror lab offers a year round mirror making class. First time mirror grinders are now recommended to start with 10 inch blanks. (8inch is still acceptable). First timers are also recommended to work towards a focal ratio of f/6 as this is the easiest.

    Course description:
    Student will construct a ceramic tiled tool for grinding. Basic grinding techniques to acheive spherical curve will be demonstrated. The making of a pitch lap for polishing and figuring will done for each student. How to perform the Foucault and Ronchi tests. Guidance in the use of software to make Millies-Lacroix plots.

    Class Price $100.00
    Every Saturday from Noon until 4pm we are at the
    Science Center of Pinellas County Inc.
    7701 22nd Ave. North
    for more information contact Paul McNabb at 727-345-5713

    The Fine Art of Mirror Making

    The mirror lab offers a class for those interested in grinding and polishing their own telescope mirror.

    Grinding Starting with 60 grit going all the way to 5 micron cerium oxide (CeO) the basic curve is created (11 hours)

    Making a Pitch lap After grinding, a new tool is made out of pitch. This is used to polish the mirror smooth.

    Polishing (8 hours minimum)

    Testing This done concurrently with polishing and figuring. (it only takes a few minutes with our robotic foucault tester)

    Figuring It might only take a couple of minutes and a few strokes to turn a spherical mirror surface into a fine parabolic reflector.

    Instead of glass we use
    ceramic tile glued to a wooden base
    as our grinding tool

    We have molds for making many
    different shaped pitch laps

    blank aka mirror blank. This is a flat piece of glass, either plate glass or pyrex, that is ground and polished into a telescope mirror.

    f/ratio - the focal length divided by the diameter of the mirror. Less than f/5 a mirror is termed "fast" and is good for wide field viewing. More than f/6 and a mirror is "slow" and better for high magnification and planetary work. Through much trial and error we believe f/6 is the most preferred f/ratio.

    Focal Length - measured from mirror surface to a point where a reflected image is formed.

    grit size - the number of grains per inch (e.g. 60 grit has 60 grains of silicon carbide per inch) The larger the number the finer the grain.

    parabaloid - the perfect shape for a mirror to reflect an image. A spherical shape is naturally formed by the grinding and polishing process. It"s a little trickier to deepen the mirror just the right amount to turn it into a parabaloid.

    radius of curvature - twice the focal length. This is the radius of an imaginary sphere that the mirror surface conforms to.

    sagitta - a fancy term for the depth of a mirror. The sagitta is created by grinding away the surface of the mirror blank.

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