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26354

Re: Non Newtonian Fluid

Thanks for the response. I saw your write-up on thin mirrors some time ago. When I was working on my 18" 10mm thick (not meniscus) I found that cooldown time
David Henderson
Jun 10
#26354
 
26353

Re: Non Newtonian Fluid

... Roughly same thickness. There's a story here... The slumper saw this as a potential business so offered me a blank if I made a mirror and said who slumped
Mel_Bartels
Jun 10
#26353
 
26352

Re: Non Newtonian Fluid

Brilliant Mel. Glad to hear you are pushing the envelope. Quick question. Does the back have the same curvature as the front? ie is it the same thickness all
David Henderson
Jun 10
#26352
 
26351

Re: Non Newtonian Fluid

Amazing specs. Best wishes and looking forward to the result. At what point do we call these bowls instead of mirrors? -Ryan
Ryan Brooks
Jun 10
#26351
 
26350

Re: Non Newtonian Fluid

I am successfully figuring a 25.1 inch F/2.62 thin meniscus mirror with tool on top over full sized lap. I built a two way stroking and spinning machine to
Mel_Bartels
Jun 10
#26350
 
26349

Re: Non Newtonian Fluid

I liked the associated video of the polisher in action. I guess full sized lap and mot is a no go in this situation. On 10 June 2017 at 15:22,
David Henderson
Jun 10
#26349
 
26348

Non Newtonian Fluid

Not sure if anyone else has mentioned this polishing method for steep aspheres on this list.Just came across a 2010 article in OPtics express by Kim and
radicell2
Jun 10
#26348
 
26347

Re: Available plate glass

Thanks all, I may try Aqua Jet to see if they will accomodate my needs. Will let you know the results. David
walking_david
May 26
#26347
 
26346

Re: Available plate glass

We tried biscuit cutting plate glass with a homemade device and grit and found that it is slow, noisy, messy, and tedious. Cutting with diamond hole saw is
Guy Brandenburg
May 26
#26346
 
26345

Re: Available plate glass

Prasad my first attempt at mirror making back in the 60's involved buying 2 porthole glasses, plate glass 14" dia 1" thick pricely sum of 48/- (shillings)
walking_david
May 25
#26345
 
26344

Re: Available plate glass

Prasad I found a 150 pound slab of glass on craigslist for free. It’s about 19 mm thick and I use a diamond tile saw to cut it into circles. I found a
    Charles Cobb
    May 25
    #26344
    This message has attachments
    26343

    Re: Available plate glass

    ... i'm not david but i know of one answer... ... if you take a metal can or metal sheet and cut it into a rectangle you roll into a cylinder and spin it on
    wkitty42
    May 25
    #26343
     
    26342

    Re: Available plate glass

    ... You can test to see if annealing is complete by placing the glass between crossed polarizing sheets. It there is any color showing you can make your
    Michael Lecuyer
    May 25
    #26342
     
    26341

    Re: Available plate glass

    David Sorry to digress, I am curious to know how you would cut circular disc especially when the glass is relatively thick. I know water-jet process is one
    Prasad
    May 25
    #26341
     
    26340

    Available plate glass

    Hi All, I know there are pros and cons regarding the choice of glass when it comes to mirror making. As you may remember I have unsuccessfuly tried unknown
    walking_david
    May 25
    #26340
     
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