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I'm still building my first full size acoustic archtop. I've built a number of semi-acoustics but with a purely acoustic instrument, things are a little different, so I thought I would ask for some advice. I have just finished gluing the bindings around the "f" holes. Normally, I would have glued the bindings on the sound board before attaching it to the sides and gluing on the back, but I chose to do the final shaping of the "f" holes after stringing it, prior to finishing. The idea is to get the maximum volume out of the guitar, by listening to it, as I enlarged the holes. If I had copied someone else's design, I would not have had to do this, but of course, I'm not that kind of person.
Anyway, my question is about the bindings themselves. On my semi-acoustics, I like to soften the edges of the bindings with a scraper. I see this a lot on other semi-acoustics too, but when it comes to strictly acoustic instruments, is it better to leave the edges of the bindings sharp? Does the softening/rounding of the binding edges, around the "f" holes detrimentally effect the sound?

The size (surface area) of the soundholes certainly affects sound, and the resonant frequency of the air mass and the soundboard. But I can’t think of a way that sharp versus rounded edges of the holes (given the same area) could possibly make a difference.

I leave them basically sharp. Just knock the edge off very slightly.

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Yeh, I've noticed that most acoustic arch top builders leave them pretty sharp. On the other hand, many semi acoustic arch top builders round them significantly. I was wondering if there was a reason other than aesthetic. I actually like the more rounded look but before I go ahead and scrape them, I thought I would check with y'all. I know all violins, violas, cellos, etc are left pretty much sharp. If rounding them would have no effect on the sound, I would have thought that at least a few might have more rounded edges. I dunno, just wondering.

I believe it is aesthetic. No doubt the flow and turbulence of the air are affected, but I suspect infinitesimally. I think having a crisp edge makes it harder to disguise imperfections in the binding. Also, a rolled edge is easier to sand quickly when prepping for finish. To me, a crisp 90° on a 1/16” thin piece of wood is more impressive.

Gross generalization alert: In general acoustic instruments are sold on the perception of quality and craftsmanship whereas electric guitars appeal more on bling and novelty. Crisp flawless mitres, seamless joints, sharp corners, etc., speak to the care and skill of a craftsman. I suspect that sense of crispness and precision leads to builders of violins and cellos to leave sharp edges to signal their skill because those indicators of quality matter to their customers. A typical buyer of a Gibson 335 are probably more focused on a gold Bigsby attached to the bride than the mitres on the binding of the F hole and so those details matter less.

Of course as with any esthetic consideration, it is personal taste. There will alway be counter examples. No doubt there is an acoustic guitar out there of extreme quality and craft with no sharp edges and deliberate gaps.


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