Last time I worked on this I left the banjo neck inserted through the holes in the gourd with the heel of the neck square. Now I have to carve the heel into a concave shape to make it fit the convex shape of the gourd. This is an aesthetic issue as well as an acoustic one.
First I need to know what the shape of the gourd is. It is round in two dimensions, so I will measure it in two dimensions and mark the neck. I used a piece of household wire that I had lying around to measure the curve.
I can bend the wire to the shape of the gourd and then use it to put a pencil mark on the neck.
I did the same thing to measure the curvature of the gourd around the rim.
Then I marked the curve on the finger board.
Now I need to carve away the wood to make it conform to the marks. I started by marking some straight lines which approximate the curve so that I can cut away a bunch of it with my panel saw.
I clamped the neck onto the bench and cut the line down to the dowel stick using my panel saw.
Then I cut along the dowel to release the wedge of wood.
And there you go. A large chunk of wood has been removed all at once.
I tried to cut away the cheeks down by the dowel stick using the panel saw, but the tip of the saw was butting against the top of the heel, so that didn't work out very well.
So I went back to my chisel to cut out that wood.
Darn! It happened again. Sloppy chisel work has split off a large chip from the neck.
I guess I need some lessons in how to use a chisel. Not much I can do about this now except to put it aside and try to correct it later. I cleaned up some of the other bits with the chisel.
Then I started to cup the heel using my hook knife. This goes slowly because the knife only removes a little bit of wood at a time.
I also used the rough side of my shoe rasp to move things along.
Here is a view of a preliminary fit up to this point.
I got out my Exacto® set to see if I could move this along a bit faster. The set has a round gouge that I can use to cut away the wood.
Here is a view of a better fit.
I gouged and gouged and gouged. The end of the heel got pretty rough, but the wood was coming away.
I finally had taken out enough wood that the fit of the heel to the gourd seemed pretty good. It is difficult to see the shape of the heel in the photographs, so I have posted some 3D images below.
Then I took my hook knife, my scraper, and some 80 grit sandpaper to the heel to smooth it out. Here is what I ended up with.
The heel doesn't have to be completely smooth because it will be up against the gourd.
OK. Now it is time to deal with that chip that I broke off while doing this work. Here it is.
You can also see that pesky wooden pin that I put in the wrong place. I can't fix the pin, but I can fix the chip with some 80 grit sandpaper. Here is the same part of the neck after I have redefined the shape of the neck a bit.
The chip is gone. I made the same correction on the other side of the neck to keep it somewhat symmetrical. Here is the result of the carving.
The joint is not air tight, but it should be OK. Carving the heel takes a long time.
I spent about 3 1/2 hours carving the heel.
Original post date July 27, 2008