Re: [ATM] Updated pictures of 8"f6 mirror............

["John and Bernadine Murray" <onslow@cyberone.com.au>]

Lesson 2 for strine is "Onya mate"........

G'day... (I'm trying to learn a second language)




ON PITCH:

	The results on the mirror surface are a good indicator. Results are
an indicator of the effectiveness of all those other things too. That is
good and that is bad. You have so much control. But there are so many things
to control.

That's true, The thing I'm having trouble controlling is temp and humidity.
Like a lot of people I don't have ideal polishing conditions in the garden
shed. I'm learning now to polish when they are suitable and not when they
suit me........



ON SHORT (1/4D) STROKE:
	The short stroke is a cause of roughness because it is "the nature
of the beast" to be too regular. It is more difficult to add variation to
short strokes. You just can't vary much shorter and if your variation is
only towards longer, the average is longer. The 1/4 stroke is probably not
extending beyond the width of the facets. Each facet would only work one
zone. Can't get much more regular than that.
	It is also the nature of short strokes that a larger portion of the
stroke is in the rougher action of starting and stopping of the motion.

Yep, that all sounds reasonable........... So back to the 1/3 stroke........



JOHN'S MIRROR AND LAP:
	John is in the experimenting phase. He wants to play a bit to see
what happens. That is a good thing to do what with all those previously
mentioned variables and more. He tried 1/4 stroke. It happened that the work
space was warmer than with previous work. He considered that the lap may be
too soft. It might be. I was letting him know I think that is not the
problem.
	Looking at John's results for the specified actions, I have seen no
reason at this time to question the lap beyond a possible minor temperature
tweak. That does not mean that it was or was not used at the ideal
temperature. It may work better at 25 or maybe 19 than at 21 or 22 C.
	Someday the lap might be just plain worn out. Then a new one will be
called for if the mirror is not finished before then. Until then I suggest
finding out how well this one works. 
	 I try to NOT explain in total detail every suggestion I make. Even
so, I'm still too long winded on partial explanations. You can see I need to
get better at that. Heee HEEEE! I have trimmed half of my comments out of
this post. The message gets lost in the details.
 
Ah hell, details are important. It's just deciding if something that you
think is of no consequence is of no consequence or is actually the ONE
detail you need to crack the problem. But that applies in life overall as
well..........

Cheers

John Murray
Whyalla
South Australia

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