Re: ATM 10" help - TDE?

["Richard Schwartz" <richas@earthlink.net>]

NO.   The blind test is intended for use during grinding.

If you are figuring, you should use your foucault tester.  The errors you
are dealing with at this stage are too small to be seen with the blind test.

. . . Richard

----- Original Message -----
From: "Tyrone Steele" <atm@pivotmusic.com>
To: "ATM" <atm@shore.net>
Sent: Monday, September 30, 2002 7:08 AM
Subject: Re: ATM 10" help - TDE?


>
> I performed the "blind Test" as described by Richard Schwartz  And it's
not
> TDE!
> In fact, after looking at the mirror surface using the blind test (should
be
> renamed to the "venecian blind test" for accuracy) I found that the shape
is
> quite near parablola.
> So, it seems to me that the folly of using a focault test to determine the
> edge shape (whether TDE, TUE or otherwise) is that both shapes are
> interpreted alike.
> I had recieved so many different points of view and alternating
> determinations from folks about those tester photos I posted (thinking it
> was a TDE), that it was becoming frustrating.
> So just for the record the blind test can be used effectively just prior
to
> the figuring stage, especially when in doubt of the outer edge of the
> mirror, as well as just prior to polishing.
>
> I will be moving on to the figuring stage next.
>
>
>
> This is the follow of
> ----- Original Message -----
> From: Richard Schwartz
> To: Tyrone Steele
> Sent: Friday, September 27, 2002 8:20 AM
> Subject: Re: ATM 10" help - TDE?
>
>
> Try www.megspace.com/science/sfe/i_fa_art.html.
>
> Because this test is done at a grazing angle, you can do it during
grinding
> of the last two grades of grit.  In the example above, it should be
obvious
> that there is a serious turned down edge.   This is the blind test.
>
> For the red-out test, ask Bob May.  He has some ideas on it over and above
> mine.   I have been doing the red out test for a long time, but was very
> surprized a couple years ago to see Carl Zambuto doing it.  He was kind of
> sneaky, just briefly holding a mirror up to the light and glancing at it
> edgewise...   I think I alone knew what he was doing.  The red-out test is
> described in the attached file. (associated pictures not included)
>
> . . . Richard
>
>
> ----- Original Message -----
> From: "Tyrone Steele" <atm@pivotmusic.com>
> To: "Richard Ozer" <rozer@ois-online.com>; "Richard Schwartz"
> <richas@earthlink.net>; <atm@shore.net>
> Sent: Wednesday, September 25, 2002 8:17 PM
> Subject: Re: ATM 10" help - TDE?
>
>
> >
> > Agreed.
> > I have no idea what you're talking about.
> > If you mean the sharpie test, yes that was done many times.
> > What the heck is a 'blind test'.
> > Is that sarcasm?
> >
> > ----- Original Message -----
> > From: "Richard Ozer" <rozer@ois-online.com>
> > To: "Richard Schwartz" <richas@earthlink.net>; <atm@shore.net>
> > Sent: Wednesday, September 25, 2002 2:58 PM
> > Subject: Re: ATM 10" help - TDE?
> >
> >
> > >
> > > Can you elaborate on these?
> > >
> > > RO
> > >
> > > ----- Original Message -----
> > > From: "Richard Schwartz" <richas@earthlink.net>
> > > To: <atm@shore.net>
> > > Sent: Wednesday, September 25, 2002 12:22 PM
> > > Subject: Re: ATM 10" help - TDE?
> > >
> > >
> > > >
> > > > How did it look under the red-out test before you started polishing?
> > How
> > > > did it look under the blind test?   Those provide a good check of
the
> > > > quality of fine grinding, but I betcha you didn't do any such thing!
> > > >
> > > > . . . Richard
> > > >
> > >
> >
> >
>
>