Step 3: Time to cut and drill
Once you know exactly where you want the first hole, use a punch to create a starting point and then mount the stock back into the vice. The punch isn't necessary, but it helps to keep the drill bit from wandering when starting the hole.
Double-check the second hole location before drilling it. Once two holes are drilled, triple check the hole locations by mounting the drop bolt on the bike and sliding the brake into place. The brake pads should align with the rim. If the holes are spaced incorrectly, there will not be enough pad adjustment on the brakes to make them align with the rim. If that happens, start over.