Operation 50: Drilling Operation

For the drilling operation, each semi-cylinder will be drilled separate than the others. The previously milled flat surface of the semi-cylinder will be facing down and sitting on 1.250" tall parallels as shown in the picture to the left.

Notice that the concave surface of the semi-cylinder is facing up and will be the surface that the drill will enter. When drilling on non-flat surfaces, drills will walk even more than when drilling on flat surfaces.

The approach for drilling into this surface is to first plunge a flat round surface with the 1/2" endmills. Only plunge deep enough to create a flat surface. After plunging the 1/2" endmill, use the 3/8" spot drill to create a small dimple on the flat. This dimple will then align the drill tip of the 17/32" drill used to drill through the semi cylinder.

The hole needs to be on center of the semi cylinder as seen in the part drawing. Use the edge finder to pickup the Y axis coordinate from the inside surface of the master jaw in the vise.

An indicator will need to be used to pickup the centerline of the semi-cylinder in the clamped position in the vise.

Ask instructor to demonstrate how the indicator is used to pickup the centerline of the semi-cylinder when ready for that part of the setup.