Re: ATM Machine Grinding Advice Needed

[Alfredo Neves <arainho_cl@yahoo.com>]

Hi Anthony,


Is 18 cubic inches per hour slow or fast by your
standard?

Alfredo

--- Anthony Stillman <atmer@flash.net> wrote:
> 
> Alfredo,
> 
> From the top...
> 
> 
> >...grinding machine...8" mirror...F2.8 took about
> 16 hours.
> 
> That's about 18 cubic inches of glass in 16 hours.
> 
> Since you made your own grinding machine, if you
> plan on doing a lot of
> glass, you might want to make a generator. 
> Generating glass is much faster
> and is saves on grit.
> 
> 
> >...switched to #60 grit
> >...use a coarser grit next...?
> 
> It's not just the pits.  It's the sub-surface
> damage.  That is, it's not
> what you can see, it's what you can't see.  It's
> imperative that these
> sub-surface fractures are removed.  I know of only
> two ways to be sure that
> they are.  Time spent grinding at finer grits and
> acid etch.  After I've
> worked at 60, and that's been rare, I have done a
> couple of hours at 80 and
> then double time at 120.  Was that too much?  I
> don't know.  I do know it
> was enough.  As for an acid etch, I've never even
> considered using HF as an
> ATM.  I think those who have used it, as amateur's
> or otherwise, are nuts.
> 
> 
> >...my pitch lap should not have off
> >center facets of the lap will not spin. Is this
> >correct?
> 
> Free spinning laps will do what ever they want. 
> Sometimes the behavior
> appears to be chaotic, but mostly it's just random. 
> Off centering the
> channels/facits is a good idea so as not to produce
> ring zones.  Whether or
> not this happens depends on the stroke.
> 
> As for motor-machines versus man-machines.  I've
> seen the same behavior and
> results with both, i.e., good and bad.  It takes
> less time for an operator
> to screw up with a motor-machine.  Curiously, both
> often make the same
> sound when they do screw up.
> 
> 
> >...a 4mm chip off the edge...will be covered
> by...clips.
> 
> I refer to these as alignment fidutials.  They are a
> necessary part of
> determining the orination of any stig that may be
> persent. ;)
> 
> 
> Anthony
> 
> 


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