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THE PROJECTOR 319
(101) To measure lost motion affix a prick-punch mark to some part of the mechanism frame as close as possible to the rim of the flywheel of the intermittent movement and a similar one near to the outer edge of the flywheel rim. By fixing one point of a calliper, or an ordinary carpenter's compass, in the mark on the frame with the other point at the mark on the flywheel rim, the distance the flywheel can be rotated may be accurately measured. Be very sure to hold the shutter perfectly still while testing the flywheel rotation.
The foregoing test was developed by projection manufacturers especially for the cluebook of PROJECTION and has become the official, Standard method of checking the gear train for lost motion.
Gear Lubrication
Projectionists differ as to what constitutes the best form of gear lubrication. (102) Manufacturers recommend a fairly ample lubricant of a good grade of medium weight oil. A good quality lubricant keeps up a slow but constant washing of the gear surfaces and works out much more rapidly than heavy oil or grease, which collects dust and grit from the air. The ball bearings of the Century projector require no lubrication, and the gears of the Brenkert mechanism operate in a bath of oil. The projectionist should consult manufacturer's instructions for details of lubricating his own mechanisms. (See page 324.)
Lubrication of Bearings
(103) One, or at most two drops of high grade oil are ample lubrication for any projector bearing. More may be thrown off, resulting in a messy mechanism and/ or oily film. To reduce tendency to over-oil, use only a medium-size oil can with a small spout opening. Bearings other than those supplied by oil wells are above considered. The Simplex E-7 projector mechanism bearings are not oiled separately. Movement of a single lever lubricates all except those few points that require only very occasional lubrication.