|
OK, so the basic design looked ok. The big issue for me was how to design the mirror cell for a cassegrain. I knew it would be different from a db but I didnt know the best way to approach it..
After a bit of reading I decided on a cell that completely contained the mirror and made sure that the mirror was not supported at all by the center hole. This was mainly to prevent any distortion but apparently n case of disaster it lessens the risk of breakage in a fall.
This type of cell was going to cost a fortune if I machined it from solid. So was buying over 30mm thick plate to do the other pieces. I decided to make patterns and have them cast. I found a guy about 5 minutes away that charges $22 per kilo. This included the aluminium and having the casting T6 heat treated. This was the way to go for sure so I made four patterns to be cast - the mirror cell, the backplate, mid section and ring for the spider. I can't remember the cost but it was a fraction of the price if I had bought plate.. It machined very well which was nice.
They all went on the lathe to clean up the casting and get them to size. The backplate and center section then went on the mill to square up the sections that I would be joining. All went fairly well here..
|