GB555485A - Improvements in apparatus for the development and like processing of roll films - Google Patents

Abstract

555,485. Photographic developing apparatus. HAZELL, R. J. Jan. 20, 1942, No. 831. [Class 98 (ii)] [Also in Group XXIT] A film holder for tank development comprises a central core with two discs attached to its ends, each disc being formed as a metal spider with a spiral of wire attached to its face by spot welding to leave a clear spiral groove between adjacent convolutions of the wire. The wire and spider may be of stainless steel. As shown in Fig. 1, a cylindrical ebonite core 1 is provided with eccentric bearings 2 and 3 and carries end discs concentric with the bearings and comprising stainless steel spiders 4 and stainless steel wire spirals 5, the wire spirals being spot-welded to the spiders. The core 1 carries a triangular spring plate 7 to grip the end of the film, and is provided with a winding handle 8. A winding stand, Fig. 3, comprises a bedplate 9 carrying two pairs of bearing pedestals 10, 11, and a pair of guide posts 12, the pedestals 10 receiving the film holder and the pedestals 11 the exposed spool of film. An unwinding handle 13 is provided. The posts 12 are spaced slightly less than the film width to bow the film to facilitate winding on to the holder. The spacing can be adjusted by twisting the posts 12. The holder may be used in a daylight developing tank. Known film holders referred to include (a) a holder comprising two wire spirals attached together by legs of wire, each leg having a central part parallel to the holder axis and two end parts bent at right angles to the central part for attachment to the spirals; (b) a holder comprising a boss fitted with radial arms to which are fixed film-guiding pins, which may carry a wire spiral; and (c) a holder comprising a spider carrying a spiral of rectangular strips wound so that the broad side engages the marginal part of the film. In the manufacture of the holder, the wire 5 is closely wound between flat discs, and placed in a spiral groove 17, Fig. 4, in a brass jig 16 provided with holes 18 at the welding positions. The spider 4 is placed on the wire 5 and spotwelded to the wire by placing an electrode 24 shaped to fit the wire in contact therewith through the jig, and a pointed electrode 23 in contact with the spider. A clamping device comprises a cylindrical centre 19 pressing on the centre of the spider 4 and four arms 20 to engage brackets 21 on the jig 16 by slight rotation. A locating pin 22 prevents the spider twisting out of position.