MIT2_007s09_sol_hw03

# MIT2_007s09_sol_hw03 - MIT OpenCourseWare http/ocw.mit.edu...

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MIT OpenCourseWare http://ocw.mit.edu 2.007 Design and Manufacturing I Spring 2009 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms .

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2.007 Design and Manufacturing 1 Homework #3 Pneumatics, CAD, & Gears SOLUTIONS 1) (25 points) Note from Professor Frey: The questions on the survey are taken from a body of test material in physics known as the Force Concept Inventory. In order to preserve the value of the test for future administrations of the same test, I can’t distribute detailed solutions to the Force Concept Inventory. Suffice it to say, the questions are all based on Newton’s three laws of motion. First Law: A body persists its state of rest or of uniform motion unless acted upon by an external unbalanced force. Second Law: Observed from an inertial reference frame, the net force on a particle of constant mass is proportional to the time rate of change of its linear momentum: F = d(mv)/dt. This law is often stated as, "Force equals mass times acceleration (F = ma)." Third Law: Whenever a particle or body exerts a force on another particle or body, that second body simultaneously exerts a force the other body with the same magnitude in the opposite direction. "To every action there is an equal and opposite reaction.” 2) a) See attached drawing. Making a good engineering drawing takes a lot of time and attention to detail . It’s not as simple as putting in dimensions, although as a first criterion the drawing must have all the dimensions required to create the part. Even a single missing or ambiguous dimension will put your part on hold in the shop. There are also conventions and good practices which were introduced during the CAD lectures. Some common mistakes based on a random sampling of submissions: Use third angle projection, align views, and show hidden lines in all three views. Don’t put dimensions inside the part. Use extensions to bring all dimensions to the outside of the views. If necessary, reduce the scale of the drawing to leave more room for dimensions. Clearly indicate center lines and center marks for holes. Assumptions of symmetry can only be made if the centerlines are clearly marked.
Don’t forget to dimension fillet radii and centers. This is usually more useful than dimensioning the length of tangent lines between fillets. Use the views to your advantage. Don’t load all the dimensions into a single view.

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MIT2_007s09_sol_hw03 - MIT OpenCourseWare http/ocw.mit.edu...

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