Re: [ATM] hogging out...break out question

["Norm Prince" <princenorman@bellsouth.net>]

Side question here....

Lots of texts and people advocate the use of subdiameter tools/laps...yet 
the descriptions of "stroke" are still defined by 1/n "diameter"...in such 
instances is this the diameter of the tool or of the mirror?...the 
average?...and if it is of the mirror...MoT...am i to assume that a 1/3 
stroke of a 13" mirror on a 10" tool has an average overhang of 2.166" at 
either end of the stroke?(relative to edge)...or is it 3.666" do to the 3" 
of tool that is not there?(that would be relative to center rather than edge 
i guess)...And how does the overhang change given the same terms for ToT 
operations...?

sorry may seem obvious to others, but have never seen anyone make any 
comment on this(in books or on the web).  I am very curious on this point.

Norm Prince

----- Original Message ----- 
From: "Mike Lockwood" <melockwo@uiuc.edu>
To: "'ATMList'" <atm@atmlist.net>
Sent: Monday, December 10, 2007 13:10 PM
Subject: Re: [ATM] hogging out


> Frans,
>
> Frans Franssen wrote:
>> After having made several mirrors with blanks and tools of equal size I 
>> am
>> now for the first time going to hog out a 13" mirror with a 10" plate 
>> glass
>> tool. Which stroke should I apply to get the right depth? Should I move 
>> the
>> tool COC with the center of the tool reaching the edge of the mirror with
>> each forward and backward stroke? I will start with carbo # 60.  Thank 
>> you
>> for your advice.
>
> I'm guessing that if you can keep the 10" tool from rocking and moving
> around, a combination of the traditional chordal stroke (mirror on
> top, carefully) and some tool on top, center over center work with 1/3
> D strokes should do a decent job.
>
> The plate glass tool is going to wear faster than the mirror (which I
> assume is Pyrex?), because it is softer and smaller, so you will have
> to determine when it is time to switch from chordal to TOT.
>
> Keep the tool beveled!  It is going to wear faster, so the bevel will
> wear away faster, too.
>
> When you do TOT, don't be afraid to stack some weight on the back of
> the tool.  Carbo likes pressure.
>
> If you have a turntable there are faster ways.
>
> Mike Lockwood
>
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
> 


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