Boyd Guitar Works - Side Bender

Side Bender Form

This side bender is a variation of many designs I have seen including Olson Guitars, Bruce Dickey
Guitars and others. Notice that the form is built at an angle such that the upper and lower bout are
level. (Since heat rises this keeps the upper and lower bout at the same temperature.)

The form is cut from plywood. After cutting the first side carefully and sanding, use a pattern bit in a
router to make a perfect copy. The side profile should be exaggerated just a bit to allow for spring-
back. I over-bend by about 1/2" on the tail block end and slightly less on the neck-block end. This over-
bend is designed into the side bender form.

I used blocks of poplar to space the two sides. Bolts with metal pipe as spacers will work well also.
I used parts of an outdoor lighting fixture to make the lamp sockets. 150W to 200W bulbs are
suggested. (Don't use plastic lamp sockets, they will melt!)

I lined the insides with aluminum foil using 3M spray adhesive.

( Side bender during assembly )

This form allows heating from "inside" the guitar side, but a heating blanket is also needed to heat the
side from the "outside".

The form is covered in 24 gauge sheet metal that is nailed in several places and the nail heads are set
flush with a nail set.

Pairs of eye hooks are placed near the edge. Eye bolts are attached to the eye hooks to allow wooden
cauls to be tightened.

The waist bend can be difficult to get in the right location if you try to bend the side all at one time. I
follow the examples of others and bend the waist on a separate pipe bender and let cool. Then I clamp
the pre-bent side in the side bender to bend the upper and lower bout.

The bent sides are pulled tight to the form using the wooden cauls and wing nuts. Wing nuts take a
while to tighten by hand so watch the temperature while you are bending.

(A digital cooking thermometer is great for this. Check Harbor Freight Tools or Wal-Mart.)

My preferred bending method is:

Thickness sand to 0.090"
Spray lightly with distilled water.
Use heating blanket or bending pipe to bend the guitar waist.
Plug in bending form light bulbs to heat it up.
Put a piece of craft paper or aluminum foil on bending form to protect wood. (also protects the
equipment from the wood oils).
Spray sides lightly again with distilled water.
Lay the pre-bent side on the form with the waist bend in the proper location
Put another piece of craft paper or aluminum foil on top of pre-bent side
Put heating blanket on top of the paper
Put sheet metal backing strip on top
Clamp down the waist.
Plug in the heating blanket and monitor temperature. 250'F to 350'F works good.
Smoothly clamp down the upper and lower bouts to the form. You should see some steam coming
out. Any cracking noise is bad at this point!
After the side is fully in bent position, unplug the heating blanket and the side bending form.
Let the side cool completely before removing it.