Re: [ATM] Plop Flop II The Sequel

[Jonathan Bishop <jonathan_bishop@sbcglobal.net>]

James,

So it seems all you "joints" are made from silicon.
This seems like an easy alternative to building
mechanical joints. How did it work?

Jon

--- James Lerch <jlerch1@tampabay.rr.com> wrote:
> Jay,
> 
> Here's my take on how to build a 27 point cell based
> on Plop results.  BTW, for
> reference we used plot to create this cell for a 22"
> F/6 made from 3/4 edge
> thick plate glass (I highly recommend against this
> type of project, but it does
> 'OK' on low powers)
> 
>
http://lerch.no-ip.com/atm/Projects/Ron_Cell_Small.jpg
> 
> So here's how I do it...
> 
> #1 Run Plop's automated cell design
> 
> #2 Once complete, click 'Graphic Plots / Cell Parts'
> and figure out how to print
> it for future reference on how the finished cell
> should look
> 
> #3 click 'Graphic Plot / Part Dimensions'
>     A) Get some graph paper
>     B) For each part, draw the triangle full size to
> create a fabrication
> template
>     C) Mark the support points and CG (in red)
>     D) For a 27 point cell, you'll need three of
> each part
>     E) Fabricate the parts, making them slightly
> larger than the template so you
> can assemble it
> 
> #4 Once you have all the part cut, got to the "Edit
> as Text" Tab, find "Var
> radius0-2".  Multiply these values by your mirror
> diameter.  Draw these three
> radiuses on the back of your mirror, this is where
> the support point for each
> cell part must coincide.
> 
> #5 Stack / assemble the cell parts up, and the only
> remaining variable is the
> angular spacing between the three separate stacks of
> support triangles.  Simply
> adjust the stacks until the spacing between the
> inner three triangles is equal.
> 
> BTW, in the image I referenced, you will see small
> ball bearings embedded in the
> silicone.  This is a BAD idea!  The problem is the
> silicone shrinks a little as
> it cures.  If the pad of silicone is not centered on
> the bearing, once cured it
> shrinks, causing uneven pressure on the support
> points.  This uneven pressure
> was easily seen in this super thin 22" optic.  We
> re-glued the cell using
> spacers that were removed after the silicone cured,
> which worked much better.
> 
> Take Care,
> James Lerch
> http://lerch.no-ip.com/atm (My telescope
> construction,testing, and coating site)
> 
> "Anything that can happen, will happen" -Stephen
> Pollock from:
> "Particle Physics for Non-Physicists: A Tour of the
> Microcosmos"
> 
> " Press on: nothing in the world can take the place
> of perseverance.
> Talent will not; nothing is more common than
> unsuccessful men with talent.
> Genius will not; unrewarded genius is almost a
> proverb.
> Education will not; the world is full of educated
> derelicts.
> Persistence and determination alone are omnipotent.
> "
>                                                     
>       Calvin Coolidge
> 
> 
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
> 

_______________________________________________
ATM mailing list http://www.atmlist.net/