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Here's the herringbone rosette, courtesy of StewMac.

Today I've been amusing myself trying to bend the curly maple binding to a radius as tight as will be required for the cutaway section. I went through three or four test pieces before I decided I was never going to be able to bend it that tightly. Then I decided to reduce the thickness -- from 0.080" to 0.065" -- and see what difference that might make. Magic! I was able to bend a 3.5" diameter ring with no trouble at all. The cutaway will be tighter than that, but the 3.5" diameter felt so easy I am reasonably confident I can do the cutaway.

Of course thinner binding means less margin for error when cutting the binding channel -- there won't any excess to speak off to sand off. This is getting interesting.

In the first picture I've cut the grooves for the inner and outer rings of the rosette. In the background you can see the test piece I did for practice.

The second picture shows a little gage I made to set the router bit depth. I'm sure a gazillion other people have done something similar. It's just a short piece of aluminum bar (too short -- it needs to be longer) with notches of varying depth.

Here's another gage I made to set the router to cut a given radius. It's just a thin piece of aluminum with 1/8" holes drilled a specified distance apart. I use a 1/8" dowel pin for the pivot point and chuck another 1/8" pin in the router. Then I adjust the spacing until the pins go through the properly-spaced holes. One has to allow for the diameter of the cutter, etc., when figuring out the required hole spacing. I calculate all that with a CAD program on my computer, so when I get to the shop there is much less chance of making a stupid math error.

I drill the holes on my milling machine, so their spacing ought to be within a thousandth or so of what they should be.

I'm sure this is also not an original idea, but maybe it's new to somebody.

(And a lot of you are probably saying , "Why does he make it so complicated?" :-) )

Here's a photo of the sound hole binding. It's the same curly maple as will be used around the top and back.

You can also see the installed rosette.

Great work on the binding and rosette! I love to hear how people overcome problems - as opposed to my methods of figuring out how to correct/hide mistakes!

nkwak wrote: I love to hear how people overcome problems - as opposed to my methods of figuring out how to correct/hide mistakes!

Quote from somebody:
The master builders seem to never make mistakes because they are skilled at recovery and coverup...and keep quiet about it.

I was amazed at how easily the herringbone purfling from StewMac was to bend. I put a heat gun on it for a few seconds and it became totally limber.

I managed to get the profile of an OM as a CAD file, and with that I could program my CNC router to cut channels to match shapes of the sides. I used those channels as molds to bend the purfling into.

When I was trying to bend bloodwood bindings a few guitars back, I couldn't get them done for a cutaway either at .0085". Then I thinned some down to .065" and bingo, they bent okay. Sometimes thinner is better.

Here's a photo of the almost complete bending form for the cutaway side. I need to get proper bolts for it, and the assembly is about 1/16' too wide. I'll have to shave a bit off the spacers to get it down to 6" so it will fit the bending machine.