2. Astronomy

Observatory Construction

In my 20s and 30s I built two observatories and two observatory telescope mounts (among a number of smaller portable telescopes and mounts). The logistics of handling parts too large and heavy for one person to pick up are interesting. The photos in this gallery will give you a feel for what those projects were like.
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46. With the observatory building complete work on the 16” reflecting telescope began. The 60 pound, 3” thick mirror blank was hand ground and polished over a six month period. Optical tests showed the mirror is very accurate, correct to less than 1/15 of a wave of light.
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46. With the observatory building complete work on the 16” reflecting telescope began. The 60 pound, 3” thick mirror blank was hand ground and polished over a six month period. Optical tests showed the mirror is very accurate, correct to less than 1/15 of a wave of light.

046ObservatoryTelescopeConstruction

  • 26. For a number of reasons the 300 lb, 15.5 foot diameter base ring was built upside down. To flip the base ring over one edge was anchored between our two cars with cables and then the tractor winch was used to raise it to a point it could be lowered on the other side.
  • 28. The garage filled up with large fabricated parts.
  • 30. The base ring was too large to transport with the tractor and trailer. The ring was large enough to park both the tractor and trailer inside. I was fortunate to have enough friends to carry the ring up the hill and place it on the lower portion of the observatory. The southern horizon in the background is about 20 miles away, excellent!
  • 32. The two major ribs that form the dome slot are attached.
  • 34. The frame was completed with the addition of 26 minor ribs. Then high temper aluminum sheets were attached to form the dome covering.
  • 36. Fabricating the two shutters that cover the 5 foot wide observing slot.
  • 38. Metal rails support the dome shutters when they are moved to the open position.
  • 40. Shutter frame and dome skin are shown in this photo.
  • 42. Following the traditional design, the foundation and support for the telescope is separate from the building. This prevents building vibrations from being transmitted to the telescope. The steel base had to be welded in place because it was too large and heavy to transport up the hill in one piece.
  • 44. Completed observatory after observing deck was added. Flag pole rotates down during observing to prevent obstruction. Construction of this observatory took 26 weeks over two summers.
  • 46. With the observatory building complete work on the 16” reflecting telescope began. The 60 pound, 3” thick mirror blank was hand ground and polished over a six month period. Optical tests showed the mirror is very accurate, correct to less than 1/15 of a wave of light.
  • 48. The fork mount for the telescope needs a large massive Polar shaft. This 7” diameter, 125 pound shaft was machined on my 14” engine lathe.
  • 50. The internal structure of the fork is shown in this photo.
  • 52. The 480 pound fork is completed except for welding on the Declination bearing mounts.
  • 54. Once the mounting base was completed the fork could be attached. The 7”, 60 pound bearing can be seen on the north end of the Polar shaft.
  • 56. This is the bearing box that forms the central support for the truss tube that holds the telescope optics. The 3.5” diameter Declination shaves are welled off center to allow for additional off center weight on the tube. In this photo a mirror is mounted on one side of the box and was used to align the DEC and RA axes to be perpendicular.
  • 57. After optically aligning the declination bearings to be at 90 degrees to the polar shaft, the bearing mounts were welded to the ends of the fork.
  • 58. The upper part of the telescope truss tube is made of aluminum to help with tube balance. This part is the upper ring. I got a TIG welding attachment to weld the aluminum parts together. Note that there are no sparks coming from this type welding, unlike the “Stick” welding used on steel in the previous photo.
  • 60. It took almost 3 hours to fixture (position) the upper ring so the 8 truss struts could be welded in place. This involved three hydraulic jacks, a ladder and one tripod.
  • 62. It took a week and a half of spare time to weld the 100 parts that make up the upper part of the telescope truss tube.
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