Plans, Instructions, Software and More Information
Mirror Making Class
Blanks can be purchased from the following companies:
(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
Ocean State Abrasives
Ebony Star Formica
C&R Decorative Surfaces
ScopeStuff has precut ebony star strips
They also have small precut pieces of teflon too.
Tampa Tube went out of business in 2007
CMC Construction Services Sonotubes
1201 North 34th Street
Tampa, FL 33605
American Discount Marine
6000 66th Street N
St Petersburg, FL 33709
($0.85/ per foot)
All American Trophy Works
6240 39th Street N Ste B
Pinellas Park, FL 33781
($20 for a nice plaque to put on your
scope with specs and a nice mirror
18891 US Hwy 19 North
Clearwater, FL 33764
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.
Mirror Making Class
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
- Ever think of making your own mirror?
- Want the best possible images from your scope?
- St Pete Astronomy Club Mirror Lab can help.
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.
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.
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
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
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.