Between 1999 and 2003 I built a single-engine airplane in my basement. Precision is important in the building aircraft, so you can’t have haphazard spacing between all those rivets that hold an aluminum plane together. Fortunately there is a tool used by many amateur aircraft builders that facilitates the even spacing of fastenings without a measuring tape, complicated math, or walking intervals with dividers. It’s called a rivet spacing tool—a lattice of stainless steel pieces with pivots at their intersections so it can be compressed or stretched. The lattice-ends along one edge of the tool have holes for marking intervals with a pencil or an awl.
My rivet spacing tool came in handy when I was building my Zip runabout. I used it to mark locations for screws at an arbitrary, but exact, 3″ interval along the edges of the plywood panels that made up the hull and deck. The screws were all countersunk and puttied, and while some would later be painted over, others along the sheer would remain visible under varnish, so even spacing was important for appearance’s sake. The device would also be handy for spacing rivets or clench nails on lapstrake boats or for spacing wire holes in stitch-and-glue boats. It can also aid in figuring out plank widths for decking.
The spacing tool comes in two sizes: 10 units and 20 units. My 20-unit spacing tool has a span of 10″ when compressed, and 36″ expanded. For wide intervals, I can just skip holes. When I found a need to mark an area longer than 36″, I would just line up my last marked hole again after sliding the tool to the first hole in the tool and keep on marking. Given the even number of holes, the tool doesn’t naturally provide a way to find a center, but if you ignore the last hole on one end, and use an uneven number of holes, the middle hole would locate the center of the span. One of the bars in the lattice has stamped diagonal lines that are used to align a crossing strip of the lattice and achieve the spacing marked next to the line. These settings are for 3/4″, 1″, 1-1/4″, and 1-1/2″.
This tool is quick and easy to use. It avoids the awkward math of fractions and decimals. The rivet spacing tool is as useful on boats as it is on aircraft and in any workshop that requires fast and accurate evenly spaced marks.
Ted Gauthier is the Deputy Fire Chief of Bloomfield Village, Michigan. His passion outside of his dream job as a fireman has always been boating and flying. Ted has built himself many things including an airplane, a hot air balloon, a kayak, and a CNC machine. His review of the Glen-L Zip appears in this issue.
The Rivet Spacing Tool is available from the Aircraft Spruce & Specialty Company and is $25.85 for the 10-hole version and $41.50 for the 20-hole version. Northern Tool also carries a 20-hole version for $39.99.
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