OK. The first thing we need is a plan. That is so we can look at it later and have a good laugh.
I began researching online different ways that people bend banjo hoops. There was one method reported by a fellow that seemed totally cool to me because of its simplicity and directness. What the fellow claimed is that he can bend a banjo hoop by soaking a slat of wood in water and then slowly bending it around a form by heating it with a heat gun.
I know that guitar builders and violin builders can heat the side wood and bend it using just a bending iron. But that wood tends to be very thin, like 1/16th of an inch. My banjo hoop is going to be made from 1/4 inch wood. I am not sure that I will be able to bend a piece of wood that thick using just a heat gun, but that one guy at least claims that he has done it. So I will try it myself.
First of all, I will need a form. I figured that I would build a form as a cylinder fixed to a circular plate. Then, I can clamp the plate in my bench vise to hold it in place. As I bend the wood around the form, I will be able to unclamp the form and move it to a new angle. Here is a drawing of my idea for a bending form.
Wood Bending Form
The vertical plate will be clamped in the vise, and the strip of wood will be attached to the cylinder and bent around the wheel. With the form held in a vertical position in the vise, I should be able to push against the wood while heating it with the heat gun and bend it against the round surface.
As I bend the wood around the cylindrical form I will use spring clamps to clamp down the wood to the form. That is why the form is a hollow cylinder and not a solid circle.
Since I have only woodworking tools ( I don't know how to work metal ) I decided to make the form out of plywood. So, I went off to the Big Box store and procured some plywood for the form. Here it is.
Plywood for the Form
That is a single sheet of 3/4 inch plywood that was 4 feet by 8 feet until it was cut in half. So I have two pieces now that are each 4 feet by 4 feet. The full 8 foot sheet would not fit in the car.
While I was there, I also found some wood to use for the banjo hoops and some two by's for a thing to bend the wood with. Here are the rest of the supplies so far.
Wood for the Hoops
The slats of wood to use for the hoops are some 1/4 inch shelving that I found at Lowe's. Each one is 48" by 1/4" maple. I use these for fingerboards as well, but for the finger boards I look for highly figured wood, and for these hoops I look for straight grained wood. It will be more difficult to bend figured wood without splitting it, so I am opting for the straight grain.
The two by's are going to be used to create a device to press against the wood as it bends. According to what I have read, the wood bends by compressing the fibers on the inside of the curve, not stretching the fibers on the outside of the curve. The wood is very intolerant of stretching, and it will split under the strain. So the idea is to push on the outside of the curve with a wooden bar to force it into the curve. This will work similar to a bending strap that is used when steam bending wood.
At least, that is the theory.
