IV. Mounting

4.7 A Frame Base

The "A" Frame base serves the same role as a tripod. The "A" frame base provides a level platform for the mount. The mount was designed so that it could be removed from the "A" Frame and installed in an observatory. The "A" Frame is made of  4" x 5" 0.250" wall aluminum tubing and the 10" truck channel that was originally to be used for the fork base. There are three leveling jacks on the "A" Frame. Figure 4.7.1.

Figure 4.7.1. The "A" Frame base provides a stable base when the telescope is used as a transportable telescope. There are three leveling jacks on the "A" Frame for leveling the telescope before polar alignment can be done, 4.7.1. The azimuth adjustment cross slide is also mounted on the "A" Frame.
 

 The leveling jacks were scrap parts from an offset plate making machine. The plate maker was purchased for $5.40 at a closed bid auction. The plate maker provided many really useful parts for several projects. Strange things can be turned into telescopes! The leveling jacks consist of an acme screw and a bronze nut set in two bearings. Each screw nut is driven by a chain drive. A DC gear motor drives each leveling jack. A four start worm is driven by the motor and drives the chain. One of the drive motor assemblies is shown in Figure 4.7.2.  

Figure 4.7.2 Three leveling jack motor assemblies are provided on each leg and the apex of the "A" Frame. Each screw jack is driven by a gear motor 4 start worm and a chain drive. The screw jacks are used to level the telescope prior to polar alignment.

 On the end of each of the screws is a leveling pad with a ball end. The ball on the leveling pad was part of a hydraulic cylinder that I got from a local farm equipment supplier. The "A" frame has three wheels for moving the telescope from place to place. A bubble level is on the A frame for leveling the telescope. The final polar alignment is done with the Alt/Az adjustments described on the Mount Base. The screw jacks are used to level the telescope prior to polar alignment.

A bubble level is mounted on the "A" Frame, Figure 4.7.3 Three double pole double through switches are used to power the motor so that the telescope can be leveled.

 

Figure 4.7.3

The bubble level was on a Cloud Height Detector that we found in the Orland scrap yard. The Cloud Height Detector also provided much of a fork mounting for the 6" Cassegrain that I used as a guide scope on the 8" Cave Astrola. A cap is on the bubble level to protect it when being transported.

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