Free Sample
The Complete Handbook of Dowel Pins & Rods
A practical reference for selecting, installing, and maintaining dowel pins and rods in professional and serious hobbyist applications
by Alumigogo Books
Chapter 1: Understanding Dowel Pins & Rods
A dowel pin is, at its most basic level, a short, cylindrical rod of material - usually steel, but also stainless steel, brass, plastic, or wood - manufactured to a precise diameter and surface finish. A dowel rod is simply a longer version of the same thing, sold in continuous lengths rather than pre-cut blanks. But the simplicity of the form betrays the complexity of its function. These humble cylinders are often the only thing holding a CNC spindle head in exact alignment with its bed, keeping a stamping die set from shearing apart at 600 strokes per minute, or preventing a $40,000 custom dining table from pulling itself to pieces in a dry climate.
To dismiss a dowel pin as just "a piece of round metal" is a mistake that can cost thousands of dollars and days of downtime. The entire purpose of a dowel pin is to locate parts relative to one another with repeatable, measurable accuracy. A screw or bolt brings two parts together with clamping force, but it does not guarantee that the two parts are in exactly the same position every time they are assembled. The clearance required for a bolt to pass through a hole allows for lateral movement, often as much as 0.5 mm on an M12 fastener. In most applications, that slop is unacceptable. A dowel pin, when installed in a properly reamed hole, locates the two components to within just a few microns