One Good Look . ..


at the dimensional tolerances on the drawings for these connec- tors showed there were two separate conditions which had to be changed if the connectors were to be cast without requiring additional machining. One was that tolerances on the teeth and slots were not accumulative and the overall dimension had to be held to ± .005. Since this dimension was over 2 inches, it was clearly beyond the capability of the process. A compromise was reached by keeping the non-accumulative condition but changing the tolerance to ± .010 on the pitch dimension. This gave the foundry a reasonable working range, yet assured the designer and manufacturing engineer that parts, cast from SAE 4330 and heat treated to RC 36-40, would be interchangeable as received. The second condition pertained to tolerances on size and location of the bosses. The foundry's first suggestion was to omit them on the castings and have the customer weld them in. But the manufacturing engineer advised that this had previously failed. The bosses had to be an integral part of the casting. A second compromise was reached. Tolerances on the dimension at the boss diameter, and the distance between center line of the bosses, were made to agree with the foundry's requested tolerances and to maintain concentricity, parallelism and squareness of the bosses within their tolerances. As a result of this cooperative effort, connectors were cast ready-to-use except for drilling finishing holes.


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