Home Movies (1944)

HOME MOVIES FOR FEBRUARY PAGE 63 Wooden Core Clock Spring Hollow Rivet Nail 100' Projection Reel 3/8" Brass Tubing 3/8" Rod v Threads Per Inch 3 3/4" B • Fig. 2 — Details of guide spool construction. Fig. A shows cross section of bearing and manner in which contact pin engages spiral slot in carrier rod. Fig. B gives dimensions of bearing and spool core. the guide reel exactly 1/5 th that of the processing reel or 3.28 inches. Thus: Length of dowel required divided by No. turns process reel (100 ft film) equals 16.5 divided by 24 equals .70" — amount film advances per turn of reel. Therefore, guide reel advances 70" divided by 5 revolutions equals .14' per turn of guide reel or approximately 1/7" or seven threads per inch. Where the processing reel is yet to be built, it is advisable to make it large enough to accommodate about 3 feet more than the 50 or 100 foot film requirements— this in order to accommodate the lineal expansion of film when wet. In other words, if you expect to process 100 foot lengths of film, make the processing reel large enough to accommodate at least 103 feet of film. With above figures established, cutting grooves in the carrier shaft was no longer a problem. I secured a length of Ya" cold rolled steel and had it machined on a lathe. As shown in Fig. 1, supports for this shaft were constructed from i/g" pipe. A length was attached at either side of the processing reel and fitted with "TV on the ends. The carrier shaft is inserted in the "TV and secured in place with cotter keys. As soon as the unprocessed film is wound on the larger reel, the carrier shaft and guide reel are removed. In use, the guide reel is moved to the starting point of the processing reel which is at the extreme left. This is done by lifting pin in the guide, disengaging it from the grooves, and sliding guide reel along the shaft to starting position. At this point, of course, all lights are extinguished, the exposed film removed from its container, and the free end secured at the starting point on the processing reel. Processing reel is started so that film is fed to it at the top. Thus, film loops around the guide spool and passes on to the processing reel, as shown in Fig. 1. The supply spool of film must be held immediately above the guide spool and sufficient tension maintained to insure traction with the guide spool and thus cause it to travel steadily forward along the carrier shaft. One can do this readily in the dark by extending the little finger and allowing it to touch the guide spool, thus keeping supply spool and guide spool in alignment. Where the processing drum is motor operated, winding a full spool of film upon it is matter only of seconds. Nor is this gadget applicable only to advanced amateur processing equipment. It can be applied to the simplest of processing rigs and, of course, performs equally well with either 8mm. or 1 6mm. film. In some localities materials and machine shop service for the shaft may be difficult to obtain at this time. But a little patience and perserverance will net results well worthwhile. In case the Ys" shaft is unobtainable or a machinist unavailable to cut the spiral groove, here is an alternative: Obtain a length of flexible metal conduit from an electrical supply house. Fit it over a metal rod or wooden dowel of appropriate diameter to serve in place of the grooved carrier shaft. Conduit is spiral wound, offering a continuous groove for the pin of guide spool to travel in moving from left to right in the film-winding operation. Still another alternative is to use a spiral grooved shaft taken from an old automobile jack (large size). Both of the substitutes suggested have been used with good success. The only drawback to use of either is that the carrier shaft governs size of processing reel instead of reel dimensions determining number of grooves per inch in shaft as set forth in the formula above, *k ~A • Fig. 3 — Guide spool and grooved carrier rod, *^»? showing, also, contact pin which engages same. '