Shop Talk – Keep it Square


Drawing lines square to the side of pinewood derby block is a very common step. To do this accurately requires a tool called a “square”. A common type of square is the “Engineer Square”. This is a simple, but highly accurate square (see Figure 1).

Figure 1 – Engineer Square
However, I prefer to use a “Combination Square” (see Figure 2). The Combination Square is sufficiently accurate, and has features not available on the Engineer Square.

Figure 2 – Combination Square
The Combination Square provides the following features:
– Draw 90 degree and 45 degree lines,
– Adjustable ruler position (allows use as a depth gauge and a drawing guide),
– Simple bubble level,
– Scribe tool – I use this to make an indent in the wood where I plan to drill. This minimizes drill bit “wander”.
Combination Squares come with 6 inch or 12 inch rules. For carpentry work, the 12 inch version is generally used, however, for pinewood derby use, the 6 inch version is much more handy.
Adjusting the Ruler Position
1. Loosen the locking knob,
2. Slide the ruler to the desired position,
3. Tighten the locking knob.
Drawing a Line Perpendicular to the Block (see Figure 3)
1. Ensure that at least 1-3/4 inches of the ruler is extending beyond the head of the square,
2. Hold the head of the square tightly against the block at the desired position,
3. Draw the perpendicular line.

Figure 3 – Drawing a Perpendicular Line
(User’s right hand not shown for clarity)
Drawing a Line Parallel to the Block (see Figure 4)
1. Extend the ruler the desired amount beyond the head of the square (i.e., if you want a line 1/2 inch from the edge of the block, set the head at 1/2 inch),
2. Hold the head of the square tightly against the block,
3. Place the pencil at the end of the ruler, then
4. Slide the head of the square along the block, keeping the pencil tight against the end of the ruler, and the head of the square tightly against the block.

Figure 4 – Drawing a Parallel Line
(User’s right hand not shown for clarity)
From Pinewood Derby Times Volume 9, Issue 6
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