Thought I'd move to a new thread to show my progress on this project.
Elsewhere (
http://www.iceinspace.com.au/forum/s...ad.php?t=31846 ), I found that the Astrosystems DG-2 heater, while a nice size for the mirror, won't fit in the secondary housing. So I've swapped for the DG-1.
Having connected up 12V (using the dedicated 12V outlet on the Thousand Oaks Dew Heater controller) and checked the circuit was working, I started the mechanicals. Pictures show the heater size relative to the secondary and relative to the secondary holder.
Cleaned up the mirror back with metho and fitted the DG-1 with some automotive silicon (RTV, from Supercheap). Left to cure overnight.
While waiting, took the opportunity to do some work on the mechanicals. Took any sharp edges off the end of the central mounting screw since it may screw through the holder into the cotton wool packing. Stretched the spring a little to give a bit more rigidity. I noticed that the three collimating screws had been chewing into the washer. One at a time, I removed and cleaned up the ends of the screws, finally with some fine emery paper until they were silky smooth. Filed down and used emery paper on the washer to get some removal of the deep gouges, and decided to fix it to the end of the secondary holder with a few spots of silicon. Firstly to stop it falling off when removing the secondary holder. Secondly to make the three collimating screw ends contact clean metal away from the early marks which covered much of the surface at the radius of contact.
Drilled holes in the secondary holder (on opposite side to the focusser), one for the wires to exit, one to provide access to the temperature adjustment pot on the DG-1. Packed the holder with about five balls of cotton wool, put four blobs of silicon on the secondary and put it in place. It fitted very neatly into place and the mirror clip was put back on. See photos. I covered the access hole with a small piece of self adhesive flocking paper since I had plenty. The wires exit a hole fitted with a rubber grommit.
Left some hours to set, then gave the secondary a wash, then reinstalled in the scope. Looking good. Wiring next week.
