Update 13/05/05
After a bit of a hiatus, I've been back to work for a few days now.
Polishing really was a bit of a chore. In total it took about 7 hours of solid polishing to get the mirror fully polished out to a sphere. With about 1 hour of polishing still to go I couldnt resist putting it up on the focault tester to see if I was near a spherical surface at all. To my amazement it tested perfectly for a sphere (at the exact focal point the mirror darkens evenely across its entire surface without any areas highlighted in light or dark). Feeling very pleased with myself I proceeded to complete polishing asap. Once I was satisfied with the polish, I threw it up on the tester once more and still it was perfectly spherical. Ok on now to parabolising.
I began parabolising this evening with a 10 minute session using the classical parabolising stroke, (mirror on top, moving from left to right in a W shape with the center of the mirror always approaching the edge of the lap and the end of each stroke). This needs a softly softly approach so I took extreme care here. After a couple of hours for the mirror to cool to ambient, I put it up on the tester, although it was now clearly no longer a sphere (the center had deepened) it was clear that I need another parabolising session. In fact it was not far enough from a sphere to get quantitive measurements of just how far it had departed.
I'm writing while I'm 'cold pressing' the mirror against the lap in advance of another parabolising session before I go to bed.
Results tomorrow.
  