The 12.5" Dall-Kirkham
                                                                                             (click on images to enlarge)

  This is a 1976 photo of my friend, Master Machinist Bill Loumaster, and the
  telescope he designed and built. Bill got more enjoyment making it than using
  it and so he sold it to me around 1975 or 1976. The 12.5" f15  Dall-Kirkham
  mirror set were purchased from Coulter Optics around 1974. The design of
  the  telescope is entirely his and he made everything himself from the tripod to
  the OTA, The telescope tube was made by rolling fiberglass cloth layers to a
  wall thickness of 3/16th of an inch. He rigged up a frame for the cloth that
  continuously rotated during curing so that the tube walls would not sag. He
  made the 9" worm gear and worm from, if I remember correctly, out of 
  stainless steel and lapped them. Bill won a Unique Design award at the 1983
  Riverside Telescope Maker’s Conference.

  After getting the telescope I replaced the finder and beefed up the fork arms.
  It was mounted in my permanent observatory for about 15 years and then in
  2006 I replaced it with a 16" Meade LX200R.


 
  This is the telescope when it was in my observatory. The RA axis of the mount came
  from the front axle of an old pickup (I do not know the make or year of the vehicle), hence it is
  has tapered bearings. The  box-like structure of the mount is very hefty, being made of 1/4" steel
  plate, and abundantly ribbed underneath with 1/4" plate to hold the RA axis. The mount, including
  the light weight fork (made of square steel tubing with 1/16" walls), weighs 80 lbs. I made the red
  painted stand that supports the mount and OTA. I fabricated it in one day. This is super a super 
  fast time for me to build something. At my current age it would probably take me a lot longer. The
  box extending at the end of the OTA is a Starlight-1 photometer. Unfortunately, I never used it. My
  main interest is spectroscopy and soon after I got the photometer, the LHIRES III spectrograph
  came out.



 The clear plastic vernier of the mount gives RA pointing accuracy to one minute of time. The knob on the side  is for manually moving RA.
  This shows the mirror mount and focus mechanism. The mount, made in 1975, is Bill’s unique design and was made from 1/2" square steel tubing, 1/16th" wall thickness. The primary mirror is firmly held in place by dabs of black silicone rubber around the perimeter of the mirror, and hence does not shift. The focuser is a motor driven hardened metal rod under spring pressure against the focus tube.

The tripod weighs only 40 lbs. Based on its design I developed a method for polar alignment. First, the telescope was optically aligned on Polaris. Converting RA and DEC to azimuth and altitude I could calculate the distance the tripod needed to be moved in each direction. The altitude adjustment is made by rotating the 1” threaded rod of the south leg the correct number of turns. The azimuth adjustment was made by making the correct number of turns of a threaded rod that moves a plate under the west leg.
  
 The sliding plate under the west leg for
 adjusting azimuth.
 

 
This is the inside of the RA drive. Note that there are letters in the image. "A" is
the spring loaded adjustment to control for backlash between the worm and
worm gear. The worm gear has 510 teeth. "B" is the canister holding the small 12V DC motor that drives RA. "C" is the small wheel of the motor, just barely showing, with a neoprene O-ring on the running surface.It turns on a conical shaped part that is attached to the first gear in the system, the worm of worm gear "D". "D" has 110 teeth. Sidereal speed is reached by moving the motor, and hence the small wheel (with the neoprene O-ring) along the tapered part it turns on. "E" is the second worm gear which can barely be seen. It has 108 teeth. "F" is the knob for manually turning right ascension.
 

Home Page