MACHINE SHOP WORK

Love our channel? Made during WWII by the U.S. Office of Education, part of the Federal Security Agency, this training film was one of a series used to educate wartime factory workers. This particular film demonstrates how a machinist should read and use a blueprint to finish making an iron casting. The machinist is variously shown studying the blueprint at a work desk, comparing the blueprint to the casting in progress, and checking measurements both at a work desk and while the iron casting is on a machine being finished. Production credits: "Machine Shop Work - Fundamentals of Blueprint Reading, No. 3 Principal Dimensions, Reference surfaces and tolerances." "United States Office of Education Training Film / Federal Security Agency" (0:07). Credits–Produced by Division of Visual Aids, U.S. Office of Education (J.W. Studebaker, Commissioner) and Federal Security Agency (Paul V. McNutt, Administrator) (0:16). Main title again (0:30). Lone white male machinist holds blueprint in workshop (0:40). Blueprint for finished iron casting (0:51). Closeup of machinist’s hand holding blueprint again (1:01). Machinist sets blueprint in front of him, begins following instructions for circular iron rough casting; machinist gesturing; machinist compares blueprint to object (1:05). Blueprint again, image of cast placed on top of blueprint to show scale correlation (1:24). Visual demonstration of cross-section; blueprint with casting alongside (1:45). Dimension line on blueprint showing diameter (2:05). Image of object with labels of cast iron before and after machining (small size change in object after machining) (2:11). Machinist in workshop holding cast iron, measuring object on table by hand with ruler, blueprint visible behind (2:40). Blueprint—"f" sign on cross-section blueprint to indicate finishing needs; also thickness marked on blueprint (2:48). Closeup: machinist’s hands measuring thickness of cast iron (3:10). Thickness on cross section blueprint again with various arrows pointing to finishing symbol, thickness dimensions, etc.—step-by-step instructions of how to read blueprint (3:18). Hands of machinist in workshop measuring multiple dimensions of rough iron casting with ruler, blueprint behind (3:33). Blueprint section noting inside diameter dimensions of casting (3:40). Machinist demonstrates dimensions of inside diameter of casting (3:48). More blueprint views (3:58); machinist measuring the hub (4:22). Machinist with upper body visible studies blueprint and rough casting in workshop (4:28). Rough iron casting instantaneously transforming into finished casting, surface by surface (visual demonstration) (4:38). Illustrations overlaid on casting image to indicate correct finishing order of iron object, work in progress (5:08). Iron casting being finished by machine with machinist observing (5:31). Tolerance specified in blueprint (written note displayed, with fractional and decimal dimensions) (5:50). 8-inch diameter, diameters (bore, counter-bore, flange) noted on blueprint (6:08). Machine cutting again (6:41). With semi-finished casting on machine, machinist measures object on machine by hand; machinist reaches to check diameter of object on machine with caliber; finishing machine spins object (6:58). Machinist studies blueprint pinned to toolbox, gestures with ruler (7:12). Closeup: machine drilling hole into iron casting while spinning (7:34). Blueprint for comparison of drilling needs (7:40). Machine tool puts finishing touches after drilling (counter-boring, reaming); various close-ups of finishing process for iron cast (7:58). Machinist's hands using tools to check diameter while machine is paused (8:20). Closeup of tool—cylinder bore gauge (8:28). Tolerance note on blueprint again (8:38). Split screen comparing machined object to blueprint: two rulers and cylinder gauge measuring dimensions of iron and blueprint after finishing (8:41). Closeup: machinist’s thumb holding cylinder gauge, measurement (9:18). Machinist (upper-body, viewed from above) holds and studies blueprint, toolbox in background (9:38). Machinist holds rough work piece, checks blueprint and compares to casting (9:45). Visual of rough work piece / iron casting again but alone against blank surface (9:59). Closeup: worker’s hands checking measurements of partially finished work piece (inner diameter - cylinder gauge) (10:10). Tolerance specified (10:28). Worker studies blueprint lying on open toolbox (machinist's body/face partial view), pointing with finger (10:40). Produced by Atlas Educational Film Company.

Complete catalog record

Transcription

for every shop job there is a work drawing or blueprint which gives the machinist complete specifications and information such a drawing as this should not only make clear to you all the details of the finished piece but should enable you to plan in advance the most efficient way to machine it the drawing represents the finished piece this rough casting should be enough oversized to allow for the necessary finishing operations not all blueprints are full scale or one-to-one here however the drawing is the same size as the finished piece and the rough casting is a little larger when the pieces machine it will conform exactly to the blueprint to understand the cross-section view at the right imagine that the finished work piece has been cut into along its center line this is the line of the cross section that part of the drawing represents the finished piece as it would appear in such a view as this the required outside diameter is 8 inches as indicated by this dimension line remember that machining reduces the dimensions of the rough work piece in the case of cast iron a roughing cut which gets under the scale and a finishing cut at least a sixty fourth of an inch deep will normally require about an eighth of an inch for each surface to be finished hence to produce a finished piece eight inches in diameter the rough casting should measure about eight and one-quarter inches this work piece allow sufficient stock for machining notice the F marks on the cross section view they indicate that the face of the plans and the inside and outside faces of the hub are to be finished the thickness of the flange is to be three quarters of an inch therefore the flange of the rough casting should be seven eighths of an inch thick will now 18 for machining the overall thickness of the piece is to be one of seven eighths inches since this dimension includes two finished surfaces the overall size of the rough casting should be at least two and one eighth inches the finished inside diameter is 4 and 250 thousands or four and one-quarter inches the inside diameter of the hub in the casting should therefore be at least a quarter inch smaller four inches or less to allow for the roughing and finishing cuts notice that no finish is required on the recess in the face of the flame it is already to size in the casting but both the outside and inside faces of the hub are marked for finishing the finished depth is to be one and one eighth inches since finishing will remove the same amount from both of these surfaces the hub of the rough casting should be of the same depth one and one eighth inches careful study of both the work piece and the blueprint is essential to good planning of the job in planning this job reference surfaces must be established for machining the three concentric surfaces and the three flat parallel surfaces finishing the large diameter of the flange first will provide the most satisfactory reference for the concentric surfaces and the large face of the flange a convenient reference for the group of flat parallel surfaces the remaining surfaces will then be finished in the following order the drilled hole the hub face the inside poor of the hub the interface of the hub and finally the reamed hole the first operation is the rough turning of the outside diameter then the roughing cut on the face of the flange notice the tolerance is specified in the blueprint in this case they are plus or minus one sixty fourth of an inch on all fractional dimension and plus or minus five thousandths of an inch on all decimal dimensions unless otherwise specified this means for example that the 8-inch diameter may be either a 64th inch less than eight inches or a 64th inch more than eight inches the finished diameter of the counterbore could vary from four inches and 248 thousands to four inches and 252,000 tolerance therefore is the permitted variation from a specified size remember that the flange is to be three quarters of an inch thick and finished on only one side be sure that the finish facing cut machines the flange to that thickness try the calipers set at 8 inches to check the finishing cut on the outside diameter this cut will complete the machining of the two reference surfaces the blueprint specifies a whole one inch and five hundred thousandths in diameter it should be bored five thousands under that size leaving a minimum of star for reading with the piece reversed in the chuck drill the hole the other operations on this site are to face the hub counterbore the hub face its inside and rough and finish bore the hole with the same tool face the hub counterbore it face it inside and bore the hole after finishing these surfaces the hole is reamed and its diameter check it is one inch and 500 1000 this meets blueprint specifications because it deviates only 1000 from the required size always make a final check of the work before removing it from the lathe to be sure that it meets specifications the overall thickness measured from the reference surface is one and seven eighths inches as required the hub bore is finished to a depth of 1 and 18 inches as specified its diameter is 4 inches in 250 1000s which again is within the tolerance limits of plus or minus 2 thousands remember that thorough study and accurate interpretation of the blueprint are essential to satisfactory performance on every job the blueprint supplies you in technical language with complete information about the finished job check the rough work piece with the blueprint dimensions to be sure that it is sufficiently oversized to allow for cleaning up and satisfactory machining in studying the blueprint choose reference surfaces to be finished first which will provide the easiest means of getting other surfaces concentric and parallel remember to maintain a constant check by measuring the result of every job operation to see that it conforms to the blueprint specification be sure that you understand what tolerances are permitted on each dimension but do not relax standards of accuracy never forget that intelligent study of the blueprint is your best assurance of doing your job efficiently

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