Use a DIY Guide Block

Build a simple L-shaped guide from two scrap wood blocks that physically constrains your drill bit to enter the workpiece at 90 degrees.

How It Works

Two flat, square-edged blocks of wood joined at a perfect right angle form a V-channel or corner that the drill bit rests in. When the guide is held or clamped against the workpiece, the two perpendicular surfaces prevent the drill from tilting in either direction. The guide acts like a portable fence that forces the bit to stay vertical as it enters the material.

Instructions

1. Select two pieces of scrap hardwood with flat, square edges (at least 2 inches on each face). Sand the mating surfaces flat if needed
2. Check the inside corner with a combination square to verify it forms a true 90-degree angle
3. Glue or screw the two blocks together at a precise right angle, forming an L-shape or V-block
4. Let the glue dry completely if using adhesive
5. To use: place the inside corner of the L-block directly against the drill point on the workpiece
6. Press the drill bit into the corner of the guide
7. Begin drilling while keeping the bit pressed firmly against both inside surfaces of the guide
8. Once the bit has entered the material 1/4 to 1/2 inch, the hole itself guides the bit. Remove the guide and continue drilling

Tips

• Use hardwood (oak, maple, beech) rather than softwood — the guide surfaces last longer and provide a more accurate reference
• For an upgraded version, drill a perfectly perpendicular hole through the guide block using a drill press, then use that hole as a bushing to guide future freehand drilling
• Making several guide blocks with different pre-drilled hole sizes creates a reusable set
• Clamp the guide to the workpiece when possible to free both hands for controlling the drill
• A speed square held alongside the drill bit serves the same purpose as a guide block and is already in most toolboxes

Common Mistakes

• Building the guide with blocks that are not truly square, which introduces the same angular error into every hole
• Not verifying the guide's right angle with a square before using it
• Not pressing the drill bit firmly against both guide surfaces during the initial entry
• Using softwood blocks that compress and deform after a few uses, losing their accuracy