DIY

WORKSHOP

HOLE PATTERN TRANSFER

Prevent hole misalignment in mating parts. By Mose O’Griffin

Illustrations by Tim Lillis

Anyone can stuff a drill bit through a piece of material, but with a little thought and practice, you can develop the skill to produce a hole pattern that allows for accurate mating of parts, to within 2. Use a transfer punch a few thousandths of an inch (To achieve this level to mark the bottom plate. of accuracy, you’ll need a drill press; cheap ones To accurately transfer the pattern of holes, put can be found for about the same price as a nice a ¼"-diameter transfer punch down each hole battery-operated hand drill.) Follow these guidelines you want to duplicate, and tap it with a hammer and you’ll produce holes that are right where you (Figure A, next page). The little dimple you make want them every time. under the center of each hole is a very important

For this example project, let’s say you want to beginning point. transfer, with precision, a 4-hole pattern, with

¼"-diameter holes, from one ½"-thick steel plate to another.

the 2 plates from moving relative to one another, such as setting a heavy object on the top plate.

1. Immobilize the 2 plates. Clamp the top plate to the bottom plate while transferring the pattern, or find another way to prevent

3. Drill a pilot hole.

Before you start drilling, let’s take a closer look at the common drill bit (high-speed steel, 118° point angle, 2-flute, “jobber’s length”). Looking straight down the point, the part inside the small circle is called the web (Figure B). This part of the bit does

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