Side Bending

Re-sawing

The sides start out as book-matched pieces of wood about 18 inches long, three and a half inches wide and less than an eighth of an inch thick. A nicely-grained piece of wood is resawn on the bandsaw to make the two book-matched pieces.

I put them through the thickness planer and then through the drum sander to bring them to the appropriate thickness.

Finally, they need to be bent. This was the scariest part—until I tried it! Side bending is accomplished with a combination of heat and moisture. Heat relaxes the internal cell structure of the wood, allowing the cells to slide past each other and change shape. The moisture is only necessary to keep the wood surface from burning. If the bending apparatus doesn't get too hot, the water is not actually necessary; however, a little higher temperature speeds the process.

Home made hot pipe (heat comes from a charcoal starter)

Side bender in use

I use two bending tools: a heated pipe and a side-bending form. The hot pipe is heated by means of an electric charcoal lighter connected to a light dimmer switch. The dimmer allows me to control the temperature of the pipe (which should be between 300 and 400 degrees Fahrenheit).

A ukulele side has three bends: the upper bout, the waist and the lower bout. I bend the waist first, using the hot pipe, and then transfer the still-wet side to the side-bending jig to complete the bends for the upper and lower bouts.

It's possible to make all the bends by hand using the hot pipe, but the bending form saves time and helps produce uniformity. The bending form is heated by two 100-watt light bulbs inside. As the wood heats, I gently bend it to follow the form, and clamp it into position. The heat stays on for another 15 minutes or so, and the bent side stays in the form until it cools. Occasionally it needs a second session of heat in order to maintain the proper shape.