Yup, I was thinking that this technique would/could make cutting a large
figured mirror into the required off-axis shapes a trivial exercise with
no losses so the whole mirror could be used. i.e. mass producing off-axis
newts would be a lot cheaper way to make an unobstructed scope than a
refractor. (and you dont have any color issues either so the complex
figuring and expensive glass of a refractor becomes a non-issue).
I suspect the light gathering loss would be a little more since you have a
pair of mirrors but that is easily overcome by making it a little bigger.
But the off-axis would lose no more contrast than a refractor.
---------
Phil Chambers [ptchamb@No-Spam] (S.F. Bay Area - Calif. USA)
On Tue, 8 Mar 2005, Richard Ozer wrote:
> Interesting web site that talks about this technique...
>
> http://manufacturingcenter.com/man/articles/0704/0704Waterjet.asp
>
> RO
>
> ----- Original Message -----
> From: "P T Chambers" <ptchamb@No-Spam>
> To: <jvn@No-Spam>; "The Astronomy Connection" <sf-bay-tac@No-Spam>
> Sent: Tuesday, March 08, 2005 10:18 AM
> Subject: Re: [TAC] Scope of confusion
>
>
> > The technique I am speaking of uses something like 40,000 psi water. Cuts
> > most anything absolutely cleanly and with no heat build up (one of the
> > uses is to cut very high strength steel where heating would damage the
> > heat treat). No chipping either.
> >
> > ---------
> > Phil Chambers [ptchamb@No-Spam] (S.F. Bay Area - Calif. USA)
> >
> > On Tue, 8 Mar 2005, Jim Van Nuland wrote:
> >
> >> P T Chambers wrote:
> >> > This thread makes me wonder if anyone is using high pressure
> >> > water (with grit) to cut glass???
> >>
> >> The big danger in cutting a finished surface is heat -- the hole saw
> >> can produce enough heat to relieve strain in the glass, just enough to
> >> damage the figure. The usual technique is to bore nearly through from
> >> the back, fill the cuts with wax, then finish the figuring. The final
> >> cutting must be done very slowly. And there's the danger of chipping as
> >> the saw bites through.
> >>
> >> The water can eliminate the heat, and probably also the risk of
> >> chipping.
> >>
> >> --
> >> Jim Van Nuland, San Jose (California) Astronomical Association
> >> JVN's web site
> >>
> >>
>
>
Received on Tue Mar 8 13:12:14 2005