The elevation spring
pulls back the mirror into a vertical position. When constructed
properly the mirror goes into vertical position by pure gravity, once
the elevation cord is released. However, over longer time the mirror can become stuck, it is therefore adviceable to add an elevation spring.
Construction of the elevation spring
| 1 Get
either a steel spring or rubber bands. A steel spring is better for
long time operating. If you want to set up an experimental
station and do not mind changing the band occassionally rubber is ok.
Since the steel spring solution shows a maybe unexpected use of heat
shrink tubing I will describe this solution. |
 |
| 2 Run
two stranded wire cables through either connection loop of the spring
and cover them on both ends with a heat-shrink tubing. The end loops of
the spring should be well covered by the tubes. Shrink the
tubes with the hot air gun. Do not give it a try immediately
after shrinking. As long as the spring is still hot it may deform. |
 |
3 Cut a piece of XPS which I shall call snail hook because of its strangely shaped incision. The block dimensions are 2cm by 7cm with 15mm thickness. This incision will hold one end of the elvation-spring-cable. |
 |
4 Cut another piece of XPS with similar dimensions and make a crease at one end as shown in the pic. I call this block backside hook. |
 |
| 5 Glue the snail hook to one side of the mirror mount as seen in pic of 6. Glue the backside hook on the same side of the mount to the azimuth arm as seen in the pic of 6 |
|
6 We employ again the bowline. Run one end of the elevation spring cable through the snail incision glued to the mirror mount and fix it with a bowline. The other end runs through the backside hook; also fixed with a bowline |
 |
7 Check whether the spring is working properly when you put the elevation servo in back position. |
|