Tuesday, June 29, 2010

Bending the Sides

Last night I went over to my buddy Dave's shop to bend the sides of the guitar. This is the process that I've been asked about the most by people when I talk about building an acoustic guitar. Basically you get the boards wet, heat up a pipe, and bend the wood around the pipe in a series of heating and cooling.

I used this pipe, below. Dave welded a cap on the end and I drilled an exhaust hole out the bottom-front. Then I simply shot the propane flame into the back of the pipe (held by a vise) to heat it up.

I decided to test this process out on a piece of scrap rosewood to get the feel for the bending process.

The hot pipe drys the wood out quickly so I have to hit the wood often with a water spray bottle. We noticed the sweet smell of rosewood billowing in the shop after a while.

You pretty much just have to rub the wood on the steel for a while and then you will feel the wood relax. Then you apply some pressure and hold the bend while you lift the wood off the iron. When the air cools the wood it retains it's shape.
There is a lot of checking the bends to a pattern I've drawn on a board. Then I would mark the spot of my next bend by grabbing the wood in that location and bending some more.

Notice how the wood looks lighter where the iron is touching the wood – it's drying the water quickly.

Finishing up the large round bend at the back of the guitar.

Again checking it to the (actual) template.
Both sides done.

I took these home and laid them on the back of the guitar (just to get a visual). Wow.

After these photos were snapped I decided to clamp the sides to a board in the exact shape of the template – hoping that this will keep them from re-adjusting shape before I'm ready to assemble the box. I absolutely love the look of this rosewood body and am very motivated to keep this project moving along.

Addition: I showed up at the shop at 7:30 and left at 10:30. So I'm guessing both sides and the test piece each took about 45 minutes each to bend. We did have some set-up time and some BS time. Our buddy Chris showed up too and he watched the shaping of the last board. Was nice to catch-up with him.

– Dave thanks so much for the use of your shop and for doing the welding of the pipe. You've been a big help!

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