From: James Young (jamiehy@globaldialog.com)
Date: 10/10/02-11:33:27 AM Z
>Temi,
>
>Creating tension with a strip of wood involves first laminating up
>thin strips of wood around a frame with an arc at each end, like
>making a shooting bow. It is pretty simple to do if you are good at
>woodworking and laminating. If you are not I would recommend finding
>a source for spring steel. In addition to whatever sources have
>already been mentioned I would also suggest McMaster-Carr and MSC.
>Both have extensive on-line catalogs that will allow you to search
>for what you need and they both sell spring steel of the size you
>need.
>
>Just for your information I measured the spring steel on one of my
>larger contact printing frames and it is about 0.07" thick by 1.25"
>wide. For a frame 20X24" in size I would recommend that the spring
>steel be about 0.08" thick, with the same width. Once you bend it to
>the right shape that should give you sufficient pressure.
>
>Sandy King
>
Although spring steel is the best choice, one can also just use the
mild steel or aluminum bar stock from a hardware store. It has enough
spring to be used if you position the notches at the right spot. I
have been using 3/16 inch thick by 1" wide material. I've made four
large contact frames from 12" x 24" up to 16" by 115" using the mild
steel or aluminum. and it works just fine. The idea is to not have to
force the bar so far that it will bend. the thicker bar can put a lot
of pressure without bending. If it conforms to a different shape
after a while just reverse the bend till you get tension again. I
haven't had to do this yet,so it's not something to worry about . My
largest frame, used to print negatives from my 16" cirkut has 5 large
panels to fit 16" by 115" negatives.
each panel has two bars, and I get good contact to the 1/4"glass.I
use large heavy duty washers to hold the bars down like the old kodak
frames. The frame is unfortunately hard to handle from it's size and
weight, but it does work.
Jamie Young in Madison, WI
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