Re: ATM Hogging Out -making flats????

["B. Bainbridge" <brianb@u.washington.edu>]

I would like to thank everyone who has participated in this discussion.
The explanations given in the classic books have always seemed inadequate
or over simplified.


On Thu, 8 Aug 2002, Tim Rickard wrote:

>
> Ok, I'm happy to call a truce here.  I've expressed my point of view the
> best I can, and I still think there is merit to it.  On the other hand, its
> just not that important. The differential pressure account is fine, and more
> immediately intuitive.
>
> So if it's not important, why have I been so stubborn about it?  Frankly,
> because in some posts on this thread I've sensed some not so subtle ridicule
> of my previous posts.  Like any "normal" person, I felt the need to defend
> myself.
>
> Cheers,
> Tim
>
>
> ----- Original Message -----
> From: "Ken Hunter" <kb7h@onemain.com>
> To: "Tim Rickard" <trickar1@san.rr.com>; "pdk" <pdk@tampabay.rr.com>; "atm"
> <atm@shore.net>
> Sent: Wednesday, August 07, 2002 10:31 PM
> Subject: Re: ATM Hogging Out -making flats????
>
>
> >
> > Well...
> >
> > If you want to talk typical.
> >
> > I typically use the top piece of glass for the tool and the bottom
> > piece is the mirror-to-be... By the proper application of pressure to
> > the edge of the TOP piece working the center of the bottom piece, the
> > BOTTOM disk becomes concave EVERY TIME. It will also become concave if
> > the top piece is SMALLER than the bottom piece EVEN IF YOU APPLY THE
> > PRESSURE TO THE CENTER OF THE TOP PIECE. This effect is used all the
> > time when hogging out blanks with smaller disks, pieces of pipe, cat
> > food cans and even rocks (NO KIDDING)!
> >
> > I believe if you take a poll, you'll find that MOST experienced ATM's
> > do their curve generation with the mirror on the bottom if the glass
> > is over about 12.5 inches diameter. It does work and it is easier that
> > way.
> >
> > All commercial curve generators that I am aware of work the same way,
> > with the mirror on the bottom and the tool on top.
> >
> > Most ATM's work the way you suggest on their first mirrors because
> > they are told or read that is the way to do it... It's NOT the only
> > way and for many cases it's NOT the BEST or EASIEST way. Wait until
> > you have finished a mirror or two and then, when you start to think
> > about pushing some big glass, you will be back trying to find out how
> > to make the bottom disk concave.
> >
> > It's really easy!
> >
> > Ken Hunter
> >
> >
> > ----- Original Message -----
> > From: "Tim Rickard" <trickar1@san.rr.com>
> >
> > > True, but that's why I explicitly constrained my argument to the
> > case of
> > > applying pressure to the middle of the top disk. Let's try to tackle
> > the
> > > problem for that case alone. Being a practical man, the case that
> > more
> > > closely corresponds to what people typically do is more interesting
> > to me.
> > >
> > > Tim
> >
> >
> >
> >
>
>
>