Page 174 - Robot Builder's Bonanza

SELECTING AND USING ADHESIVES 143

Butted joint. The typical butted joint provides minimal surface area for a strong bond and
is the weakest of all. Avoid it when you can.
Overlapped. Overlap the pieces themselves, instead of butting them end to end. This is
not always feasible, but it is a quick- and- easy method when the option is available. You
can readily adjust the amount of overlap as needed.
Reinforced butted joint. Overlap an extra piece of material along the seam of the joint.
Use the widest overlap piece you can, in order to increase the surface area. Apply
adhesive to this extra piece, and clamp or tape until set. You can also reinforce with
small fasteners.
Mitered. Increase the surface area of the join by mitering the ends. This is most practical
with materials that are 1/4″ or thicker. The technique is particularly helpful when join-
ing wood.
Gusset reinforced. Use gusset pieces on the top and/or bottom.

IN SUMMARY: SELECTING A GOOD GLUE
With so many types of adhesives to choose from, it can be hard to select the right one. Table
13-1 summarizes the most common adhesive families, along with their pros and cons, and the
bonds they are best used for. Table 13-2 provides various bonding recommendations for each
major adhesive family.

Table 13-2 Recommended Adhesives, by Bonding Material

Bonding to:
Adhesive Metal Plastic/Foam Rubber Wood

Contact cement OK Recommended OK Recommended
Cynaoacrylate OK Recommended OK OK
Epoxy Recommended Recommended OK OK
Hot melt OK Recommended — OK
PVAc — OK — Recommended
Solvent cement — Recommended OK —
Silicone OK OK OK OK

— means not applicable or noneffective.

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