pukko Posted April 28, 2013 Report Share Posted April 28, 2013 I'm building a hollow archtop guitar right now and I'm thinking about doing a design with multiple soundholes like I've drawn on the top here: What worries me is that there isn't a lot of wood between the holes. I see that some builders here also make split soundholes so i figured someone could chip in with some knowledge/tips regarding this. The top is maple as you can see. Approximately 6-7 mm thick (=about 1/4"). Do you think I need to reinforce the holes from the inside in some way? In that case, how? A veneer glued on cross grain? Some kind of glue applied to the inside surface? Binding the holes would strengthen them I guess, but it will be a pain in the sitting area to do it... The rest of the guitar is/will be bound with grained ivoroid. Quote Link to comment Share on other sites More sharing options...
Dean Posted April 28, 2013 Report Share Posted April 28, 2013 They do not need any extra support. They will be fine as is. Quote Link to comment Share on other sites More sharing options...
Prostheta Posted April 28, 2013 Report Share Posted April 28, 2013 +1 Soundholes on acoustics are reinforced for practical reasons. Off the top of my head I think without it they introduce unwanted overtones and eventually crack from the vibrating air pumping in/out of them. The f-holes on a carved top are less active in the acoustics of the instrument as the top doesn't pump and flex like a speaker cone as much as an acoustic. In any case, 6-7mm is positively *thick*. I would be tempted to rout out the inside specifically around the f-holes in order to provide the illusion of a thinner top even if you are not making it that thin. You could probably go to around 3mm before you could call them "thin". Quote Link to comment Share on other sites More sharing options...
pukko Posted April 28, 2013 Author Report Share Posted April 28, 2013 They do not need any extra support. They will be fine as is. Cool, thanks! +1 Soundholes on acoustics are reinforced for practical reasons. Off the top of my head I think without it they introduce unwanted overtones and eventually crack from the vibrating air pumping in/out of them. The f-holes on a carved top are less active in the acoustics of the instrument as the top doesn't pump and flex like a speaker cone as much as an acoustic. In any case, 6-7mm is positively *thick*. I would be tempted to rout out the inside specifically around the f-holes in order to provide the illusion of a thinner top even if you are not making it that thin. You could probably go to around 3mm before you could call them "thin". I am more worried of a heavy right hand strumming away, banging on the soundhole area, maybe with a wristwatch or something getting snagged in there... Yeah, 6-7 mm is kind of thick and I am thinking about doing exactly what you suggest and thin it more around the soundholes. IF I choose to bind the holes the ivoroid binding is 6 mm high so the top has to be thinned down accordingly. Some thickness might disappear in the final sanding of the top as well. Quote Link to comment Share on other sites More sharing options...
Prostheta Posted April 28, 2013 Report Share Posted April 28, 2013 Fair calls. The soundholes are relatively uncomplicated however so they are less likely to experience mishaps than say, a Cremonese style f-hole. Even then the grain is in the correct direction to support the hanging ends. Long story short, you have all options open to you. Quote Link to comment Share on other sites More sharing options...
KeithHowell Posted April 29, 2013 Report Share Posted April 29, 2013 Soundholes on acoustics are reinforced for practical reasons. Off the top of my head I think without it they introduce unwanted overtones and eventually crack from the vibrating air pumping in/out of them. In flat top acoustics there is a component of the string force running longitudinally in the sound board into which a hole is then hacked. That's why bracing is then placed around the sound hole to distribute the forces around it and up into area under the fretboard and hence into the rest of the neck. Without it the sound hole will start to distort into an ellipse and crack as you correctly state. See Cumpiano and Trevor Gores books for detailed info on the subject. Quote Link to comment Share on other sites More sharing options...
Prostheta Posted April 29, 2013 Report Share Posted April 29, 2013 Thanks Keith. The Cumpiano book is on my to-buy list however I will look into Trevor Gore's book also. It's appreciated that you termed this more accurately than I. Quote Link to comment Share on other sites More sharing options...
SwedishLuthier Posted April 29, 2013 Report Share Posted April 29, 2013 the grain is in the correct direction to support the hanging ends. +1. You will be fine with a thick top. Especially if its maple. If you are worried you might consider binding the holes as that add a tad of strength. Quote Link to comment Share on other sites More sharing options...
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