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Chapter 3 Screw It or Glue It: Fastening and Joining Parts 65
Pins
If you’re ever put together furniture from IKEA, or used an exercise machine at a gym
with a weight stack, you’ve dealt with pins used for fastening and alignment. You can
find wooden dowel pins at any arts-and-crafts store, but metal dowel pins and spring
pins are more common to use for aligning parts.
If you make a hole in a part just slightly smaller than the pin diameter, you can
hammer or press in the pin, and friction will keep it in place. If you make a hole just
slightly bigger, your pin will slide in easily and be removable.
Retaining Rings
Retaining rings can be used with pins and shafts to stop them from sliding all the
way through holes or to create pivoting joints. Figure 3-10 shows an example of a
retaining ring used in a piece of gym equipment.
FIGURE 3-10 Retaining rings on gym equipment keep the shaft of a
pivoting joint in place.
