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| Re-bracing a top http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=16281 |
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| Author: | bassethound [ Thu Mar 06, 2008 7:05 pm ] |
| Post subject: | Re-bracing a top |
I'm looking for any suggestions anyone might be able to pass along regarding removing a top from a recently constructed acoustic guitar. The series of events that need to happen seem to me to be: - remove the neck (already done) - rout the binding off - remove the finish in the area around the top rim, and around the sides - heat the rim and carefully remove the top - rebrace the top - with the guitar in a mold to hold the sides firmly in place, re-install the top, then continue with re-installation of purfling (a little wider, or maybe herringbone strip this time) and binding. - finish top and sides (hopefully leaving the back finish intact) I realize that I'll have to be very careful to get the top to fit properly, and that there will be very little room for error. I think that I can make up for any little misalignments by using a thicker binding and wider purfling. Why am I doing this (you were probably wondering right from the start)? Well, after trying several adjustments, I simply can't get this guitar to give the sound and the volume I'm looking for. After completion of the guitar, I realized and learned through talking with other luthiers that I'd made several mistakes, and here's what I'd like to correct: - primarily... open up the X-brace so that the bridge intersect it further out toward the ends - shift the X-brace slightly forward as well - scallop the braces (last time I used a parabolic profile) - install a thinner bridge plate (I did not thickness the previous one, and it was very thick maple) - thin the top... it's very highly figured sitka... and I think it needs to go down from .115 to around .100-.105 - thin the edges of the lower bout before refinishing... take them down to .085-.090 or so - correct the placement of the bridge... somehow it slipped before drilling the two locating holes, and intonation on the Low E is off / impossible to correct at present. The guitar is sitka and mahogany, slightly smaller than OM size, with a slightly deeper body (1/8"). It looks great, and plays fantastic (I got 2/3 of the equation right!). I am hoping to get more volume, and get a guitar that produces a deeper, more bluesy, thumpier sound, as opposed to the more treble heavy sound I have now (which sounds 'tinny' to my ears). Any advice would be greatly appreciated. Ken |
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| Author: | wbergman [ Thu Mar 06, 2008 8:00 pm ] |
| Post subject: | Re: Re-bracing a top |
It seems to me that if you are willing to go to all that work, you might want to try a few things first for which you would not have had to remove the neck and which do not stop you from later disassembling the guitar if they do not work. These are, reach into the guitar with a sharp knife and trim the braces a lot. Sand or scrap the top to thin it and profile the plate. Neither of these is inconsistent with a later disassembly, if still needed. |
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| Author: | bassethound [ Thu Mar 06, 2008 8:33 pm ] |
| Post subject: | Re: Re-bracing a top |
Yes, I didn't mention that I had already tried taking the braces down already. Went in a couple of times. I don't feel that I could do a proper job on thinning the bridge plate through the soundhole though... it's pretty tough stuff. Yes, I could try thinning the top a bit, I guess. But in the end, I don't mind the work. It's more of a hobby to me than anything else. Ken |
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| Author: | Blanchard [ Thu Mar 06, 2008 8:38 pm ] |
| Post subject: | Re: Re-bracing a top |
If it were me, and it has been on several occasions, I would start over with a new top. Removing, re-bracing and replacing a top is twice as much work as just removing the old top and replacing it with a new one. A whole new top will greatly simplify the removal and greatly simplify the re-binding process. I tried to save a top once and failed to get good results. I have completely replaced tops on several occasions with minimal difficulty and left no evidence that it had been replaced. Mark |
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| Author: | Howard Klepper [ Fri Mar 07, 2008 2:34 am ] |
| Post subject: | Re: Re-bracing a top |
I suggest starting a new guitar. You have no guaranty that changing this one will give you the guitar you want. Play it for 20 years and it may come around nicely. |
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| Author: | Laurent Brondel [ Fri Mar 07, 2008 6:41 am ] |
| Post subject: | Re: Re-bracing a top |
Ken, your dissatisfaction with the guitar sound may not be related to the top only. Other elements may come into the equation: neck fit, size and material, back bracing and thickness etc. How long was the guitar strung up before you decided you didn't like the sound? It may take a while for the voice of the guitar to develop. While the neck is off you could remove the bridge, carefully strip the top finish (without removing any wood), do a little perimeter sanding (do not sand material around the bridge location, especially behind it), refinish the top and re-glue the bridge in the correct location. If you're patient you can also get through the soundhole with a thumb plane and remove material on the back of the bridgeplate, then clean up with sandpaper. Shouldn't take that long to feather out the bridgeplate and will be the most effective tone enhancer. Thinning the top to the dimensions you give is a risky proposition, especially if you've already removed brace material. Then put the neck back on and call it a day. Like Howard says, move on and build another one. A sitka/mahogany OM will not usually give you a thundering bass. |
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| Author: | bassethound [ Fri Mar 07, 2008 4:02 pm ] |
| Post subject: | Re: Re-bracing a top |
Well, I've heard the voices of reason, and I concede. I was pretty set on redoing the braces, but you guys are all right... I should do whatever I can short of re-topping, then move on. Blanchard (I'm sorry, I don't know a lot of your first names), I had also considered making a completely new top, and perhaps putting this one on a future, slightly smaller guitar, so there's some room to trim off around the edges afterwards. But I think Laurent's suggestion is a happy medium, i.e. do what I can to thin the bridge plate (through the soundhole), relocate the bridge, thin the perimeter, refinish, then button it up and move on (or move on in the meantime, while the finish is curing). I'll see what I can do in terms of getting my small finger plane in there and trimming some of the plate thickness. BTW, the guitar has had 6 months to settle in. I don't think it's going to change dramatically beyond its current sound without some substantial modification (or maybe it will in 20 years, as you suggested, Howard!). Thanks again, guys. Again, the answer can usually be found here, on this forum! Ken |
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