I use this very cool fixture in my shop when building guitars. It is a Porter Cable laminate trimmer mound to a vertical slide, that I modified with a turnbuckle and spring, to lessen the weight of the trimmer upon the guitar surface as it performs its job.
As the bit spins, I rotate the body on an adjustable guitar body holder and it trims away the overhang of the top and back, with me safely on the other side of the body. It also provides great control.
Switching bits allows me to carve a perfect channel for the body bindings, in the same manner. The trimmer glides along the top and back, gently riding up and down as the arching of the top and back change. this allows for a perfectly vertical binding ledge, despite the top and back being arched. Using a hand router, would cause the router base to be at a slight angle due to the arch, and the binding ledges would not be perfectly vertical. The second set of photos show the top's binding ledge cut, and my test-fitting the figured maple and dyed maple binding strips. They drop in perfectly, and will need no sanding or scraping, due to the precise nature of this fixture.
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