Welcome to JP Astrocraft,
my little astro manufacturing company. I'm John Pratte. I spent over 40 years
as an Engineer for a large manufacturer, but recently retired and can now
devote more time to my telescope making activities. I've made telescopes for
over 50 years, including mirrors up to 20 inches.
In my search for the perfect size personal
telescope, I designed and built a 16" F4 which became nicknamed the
"Sweet
Sixteen".
Well actually I built four. Two are currently available for
sale. The 16" aperture provides enough light gathering, and the
F4 optic allows an eyepiece height of about 62" at the zenith.
The compact design is several inches smaller than most other 16"
scopes. Refer to the telescopes page for specifications and
construction details. You will see why I am proud of the
Sweet Sixteen. It is available with a mirror from Mike Lockwood, of Lockwood Custom Optics,
or from Dick Wessling, of the Pines Optical Shop.

20 Inch Tip-out Mirror Cell
I have also built a number of custom mirror cells
over the years. My cells mount the mirror on it's own
support framework and use a pivoting support at the mirror edge to prevent
binding. I do not believe slings or glued on supports are the best way to
support the edge. The larger cells feature spherical bearings at the
support triangles to reduce slop in the pivot. The sweet sixteen cell uses
channels that are shaft mounted for the levers, further controlling slop. This frame is spring loaded with stainless
Belleville washers to the mirror box frame. This construction results in a
strong, easily collimated cell that resists collimation change as the scope is
moved while properly supporting the precision optic.

I was fortunate enough to have acquired a reasonably
complete machine shop for my telescope making activities. It is great to be
able to make the proper part for a scope rather than having to adapt hardware
store or commercially available parts. See my shop section for my
equipment and custom projects for pictures of special stuff I have done.
Home Page
Sweet 16's
Custom Mirror Cells Custom
Projects Telescope Page
Pricing Contact