Graflex.org

djon · Joined: 05 Nov 2004 Posts: 174

Any suggestions for modifying (or just operating) RH-8 for maximum film flatness?

Ideas for sources and installation of extra rollers?

Anybody tried strips of Teflon tape?

John
Albuquerque

alecj · Joined: 09 May 2001 Posts: 853

Duplicate postings are discouraged.

No known way to user modify the roll backs. The tolerances are too close and the back's design was changed between knob-wind and lever-wind.

Any tape, etc. you add has the chance to change the point of focus.

djon · Joined: 05 Nov 2004 Posts: 174

It's my impression that the extra rollers were the change that supposedly add flatness with the lever-wind backs...

...did something else contribute flatness?

It's significant that the new cases accept the old mechanisms and vice versa. And the rollers are in the case, not the mechanism.

A little extra pressure from teflon tape on the Graflex non-pressure plate shouldn't change long-side focus because that's regulated by the rails that rub against the emulsion on the 9cm (or 7cm) side.

Any slop has partially to do with curvature between those rails...bowing inward or outward along the 6cm dimension.

Since I can't control outward curve without a Rollei-style glass plate (easy, but too much dust), there's nothing to be lose by laying teflon tape on the "pressure plate" so long as it doesn't press outward past those rails.

If the problem is outward curve I guess I'm out of ideas.

Any ideas about sources for teflon tape? I know of only one, an archery supply catalog.

Henry · Joined: 09 May 2001 Posts: 1662

Well, you might be able to gimmick up some teflon tape by laying down a line of Scotch® double-sided, then over that a line of ordinary teflon tape as sold in any hardware store--plumbing supplies area. I would question the durability of such, though; that teflon tape seems pretty thin. But go ahead and try it on *your* RH and let us know how it works! :cool:

djon · Joined: 05 Nov 2004 Posts: 174

Not widely known: sticky-backed teflon tape is available in a variety of thicknesses and widths from 1/4" to several inches.

I've used it in several applications...it's far more durable than other tapes, the adhesive is very strong, and very, VERY slick. It's intended specifically to provide slick surfaces for machinery, not to bind anything.

I'm amazed, incidentally, at the crude chrome finish on rails against which the film emulsion runs. I'd apply teflon tape there, too, but that would change the focus by, um, .005"...as if that's critical in a Graflex :smile: