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F. H. Richardson's bluebook of projection (1942)

Page scan 000396 from F. H. Richardson's bluebook of projection

Record Details:

Title:
F. H. Richardson's bluebook of projection
Date:
1942
Publisher:
New York : Quigley Publishing Company, Inc.
Volume:
F. H. Richardson's bluebook of projection
Leaf #:
000396
Language:
English
Subjects:
Motion Pictures, Motion Picture Technology
Collection:
Books
Format:
Books
Contributor:
Media History Digital Library
Sponsor:
Media History Digital Library
Coordinator:
Media History Digital Library
Description:
Date Added:
July 11, 2024
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3<80 RICHARDSON'S BLUEBOOK OF PROJECTION cloth around a round steel bar 7/16-in. in diameter. (75) If no such bar is available, use a 7/16-in. diameter negative carbon instead. Rub the contact surface until it is clean and bright. Be sure the surface is smooth. (76) Should any minor swelling of the metal be found it may be very carefully smoothed off with an emery wheel. It is difficult to keep the carbon contacts of high intensity lamps in good condition yet this is one of the most important items. (77) Under the action of high temperature a coating of oxide forms on the contact surfaces, offering high resistance to the passage of current. This resistance increasingly aggravates the condition, the heat generated by the resistance becoming so great between carbon and contact, that the contact metal fuses no matter how "heat resisting'' it may be. (78) This condition demands that the contacts be thoroughly cleaned at least once each day in the manner before described. Some recommend cleaning them only on alternate days, where high current values are not used, but we most emphatically do not regard that as either 152. — Positive feed unit. good practice or safe. It is no hardship to clean them daily and it provides an added element of safety.