[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: [ATM] figure stroke ten inch
Mike,
I've found your full size lap figuring page to be very helpful. You
should consider writing up a sub-diameter page with a figuring walk
through that is similar to your full size example. I'd also be
interested in how to pick the tool diameter.
-Anthony
Round Rock TX
> -----Original Message-----
> From: atm-bounces@atmlist.net
> [mailto:atm-bounces@atmlist.net] On Behalf Of Tom Fredrickson
> Sent: Monday, October 01, 2007 9:13 PM
> To: atm@atmlist.net
> Subject: Re: [ATM] figure stroke ten inch
>
> On Mon, 01 Oct 2007 17:30:16 -0500
> Mike Lockwood <melockwo@uiuc.edu> wrote:
>
> > Hi,
> >
> > Tom Fredrickson wrote:
> > > I'm working on a 10 inch mirror full size lap. I turned
> the edge and
> > > went to work with short coc strokes to clean it up. Now I need to
> > > add correction to the edge. I have been working the edge
> and it is
> > > going the wrong way. I feel I need to work the center and make it
> > > deeper.
> >
> > As you can tell from the widely varying advice you've
> received on the
> > list, there are many ways to make a mirror. Allow me to
> submit my two
> > cents worth......
> >
> > A 10" F/5 should be able to be figured with a full-size lap if the
> > pitch is soft enough. If the pitch is not soft enough, you
> will get
> > to a point where the mirror just won't correct anymore, and if you
> > force it, bad things may happen.
> >
> > The pitch can be made softer by warming it or working in a warmer
> > room. This should get you to full correction.
> >
> > I'm not sure if you've read my full-size lap figuring page,
> so here's
> > a link - hope it helps:
> >
> http://bi-staff.beckman.uiuc.edu/~melockwo/mirror_making/full_lap/full
> > _lap.html
> >
> > What I say there will also help you judge the hardness of
> your pitch,
> > which is key in this situation.
> >
> > If you have made other mirrors and are ready to try
> subdiameter laps,
> > this mirror would be a good one to start learning on. I
> would use a
> > 6" lap, personally.
> >
> > Mike Lockwood
> >
> > _______________________________________________
> > ATM mailing list http://www.atmlist.net/
> >
>
> Mike,
>
> I agree with your point about pitch hardness. I find my
> working temperature needs to be about 80 - 85 degrees. my
> mirror is 1 1/4 inch thick pyrex. How long should I let it
> stand in a water bath? I let it set for 30 minuets and found
> the edge would be warmer the the center I think this caused
> me some problems.
>
> what I don't like about warming the mirror is testing the
> mirror is not as reliable. I have read your web page and find
> it helpful. I had this mirror at 1/10 wave but the edge was
> turned down. I had to mask off 3/8 inch all around to get
> acceptable results when star testing.
>
> Also had a figure better then 1/4 wave many times but the
> edge seems to always be high. That is why I turned the edge
> with a locolized stroke to reduce the edge.
>
> Thanks for your help.
>
> -- Tom
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
>
_______________________________________________
ATM mailing list http://www.atmlist.net/