making vise clamps on the milling machine

Step 8 Pre-drill the slot

Drill bits are easier to sharpen than milling cutters, so I drilled holes to hog out most of the metal for the slot. I started with a smallish bit (I think around 1/4 inch) for a pilot hole, then opened it up to 3/8 inch. I know the drawing shows a 0.500 inch slot, but 3/8 inch plus a little is fine.

When I was done there were three 3/8 inch holes through the middle of the clamp, with their sides just touching.