Project 3: Shaft Assembly Design

Review date: Monday, April 6, 2009
Due date: Wednesday, April 8 2009

In this project construct a fully detailed assembly in NX of a shaft to hold a gear and the bearing, supports and base plate. You will start with the following parts, which are to be considered as if they were to be purchased from an external vendor. Therefore the geometry of these parts cannot be changed.

The following parts can be modified as needed and additional parts can be made as well. Your job is to finish the assembly as given in shaft_assembly.prt. When you are done the assembly must have all the details such that it could be assembled if the parts were on your desk. In other words all the holes for the fasteners must be present as well as solid models of the fasteners. A 1/4-20 socket head cap screw model is given; from this part you can modify the dimensions (using expressions) to generate a full range of SHCS. I have also given you some copies of some pages from "Machinery's Handbook: 25th edition" that give the sizes of various fasteners, nuts, bolts and the standard clearence holes for each, please use them. As the assembly stands presently you need to do the following:
  1. Add features to the shaft so that the center of the gear face is exactly 1/2 way between the two pillow blocks.
  2. Use a set screw with a machined flat on the shaft to prevent the gear from rotating on the shaft.
  3. Add c'bore holes to the pillow blocks so that they can hold the bearings. You should have a nominal line-to-line fit between the bearings and the holes in the pillow blocks (i.e. they have the exact same diameter)
  4. Ensure that there is 0.06" clearence between the shaft and the gear.
  5. Add features to the pillow blocks and the base plate so that they can be attached. Add the appropirate fasteners to your model. Also, make sure you have appropriate clearance in all holes that you add.
  6. Add four c'bore holes in the base plate so that it can be fastened down. The c'bores need to be such that the heads of the screws are flush.
When finished zip up your assembly and all the parts used (the must all be in the same directory for this to work, don't change the relative locationof the parts) and upload the zipped file to WebCT.

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