Unformatted text preview: EML 2023 – Computer Assisted Design 16 Nov 2009 Name: Complete both sides of the paper. Units are in inches. Unless otherwise specified, all distances are .01” and all angles are 0.5. a) Sketch the three datums onto Figure 1. Identity datum A, B, and C. b) What is the LMC for the 7 holes? .253 inches c) Upon manufacturing the smallest center hole has a diameter of .185 inches. What positional tolerance is allowed for this hole? .015 inches Figure 1 d) What is the major diameter of the part‘s external threads? How many threads per inch are there? The major diameter is .625 inches. There are 11 threads per inch. e) What is the minimum allowable diameter of the cylindrical feature that has the seven holes in it? 2.78 – .04 = 2.74 inches f) For the manufactured part, hole B has a measured diameter of .252”. The coordinates of the hole’s center point are (‐1.109”, ‐.004”) as measured in the coordinate system shown in Figure 2. Is hole B within the allowable tolerance for this feature? Provide justification for your answer. No, the allowable tolerance is that the center point must lie within a circle of diameter .010+.005=.015”. However the distance between the center point and the ideal center is 0.0098”. Figure 2 g) For a manufactured part, what is the maximum possible allowable distance between the centers of points A and E? The maximum distance of point A from datum B will occur when hole A is drilled at the Least Material Condition, i.e.at a diameter of .253”. At this condition, the allowable tolerance is .016”. The maximum radial distance is half of this, or .008”. The same conditions apply to hole E. Thus the maximum possible distance between the centers of holes A and E is 2.216”. h) Describe what the feature control frame means. All points on the face that this frame points to must lie within .001 of a plane that is perfectly parallel to datum A. i) What is the minimum allowable distance between surface 1 and surface 2 as shown in Figure 3? .816 + .370 = 1.186” j) Describe what the feature control frame means. Figure 3 At any location along the axis of the cylindrical feature, the surface must be within .0025” of a perfect ideal circle whose diameter is from 1.490 to 1.500 inches. ...
View Full Document
- Fall '09
- center point, feature control frame, allowable tolerance, minimum allowable diameter