Re: [photo-3d] Behind the curve

["Thom Gillam" <ThomGillam@xxxxxxxxxxxxxx>]

From: "Thom Gillam" <ThomGillam@xxxxxxxxxxxxxx>

--- In photo-3d@xxxxxxxxxxx, "Dan Shelley" <dshelley@xxxx> wrote:
 
> Thom Gillam makes wonderful curved stereocards. He explained the
procedure
> in brief one evening at the Richmond NSA convention. I do not
remember all
> the details, but I believe it involved heat and a curved press of
some sort.
> The result is very pleasing. I own a copy of one of his full moon
> stereoviews with the round pictures/chips on the curved card. It's
among my
> favorite cards. =)
> 
> Thom, are you still out there? Can you tell us more?

Dan (et al),

Yes I'm still lurking!  The subject of curved cards is one that
prompts me to speak up whenever it is broached.

First, Dan, thank you very much for the praise! BTW, the view can be
seen in the Files section (in the ThomasAtkinsGillam folder) on
Onelist, along with a few others I had handy.

As to why they did it 100 years ago, I can't attest, though I am
certain is was deliberate, and not a consequence of age.  There are
turn-of-the-century views of stereocard viewmaking that show the
cards pressed in a wooden frame which clearly had curved blocks on
top and bottom.

Why do I do it?  I found early on that the cards I made (cut from
matte board) sometimes curved left-to-right, instead of
top-to-bottom. I really just wanted flat cards, but it became clear
that I would have to do something to prevent the unwanted l-to-r
curve. 

Why unwanted? L-to-r curve results in the distance to analogous
points on each chip being unequal. Points on the left side of the
left chip will be closer to the left eye than points on the left side
of the right chip are to the right eye. Points on the RIGHT side of
the left chip will be FARTHER than points on the right side of the
right chip. 

With the curve being top-to-bottom, the distances, while not being
equal, will be LESS UNEQUAL!  Any eyestrain resulting from this
inequality is minimized.

I designed a wooden jig of my own, which is simply a frame to keep
several cards stacked together, and carved a curved block for the
bottom, giving it (approx.) a 6" radius; radius arrived at by
measuring the curve on some old U&U cards.  For the top, I made a
simpler jig with two wedge-shaped strips mounted such that they would
press down on the top and bottom edges, warping the cards over the
curved block on the bottom.  I found through trial and error that I
could put about six cards at a time between the blocks before it
became too hard to press them down.  This worked out well, because I
use an old T-shirt press to dry-mount the chips on the matte board,
and that press will do six at a time!

I would dry-mount six views at a time and transfer the still-hot
cards to the curving press. At first, I tried to weight down the
cards with a brick, but that wouldn't do it, so for a while I just
pressed down with my hand for a few minutes, until the cards had
cooled.  The curve imparted to the cards proved to be permanent, and
utterly and completely counteracted the unwanted l-to-r curve.

I later found a small press made for 5"x7" prints, which was designed
to keep them flat while drying, but I adapted my curved blocks from
the earlier press and now don't have to spend my time as a deadweight
since the new press has a screw clamp which does the job.

Thom



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