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| Questions about fingerboard exte http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=13546 |
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| Author: | Colby Horton [ Fri Sep 07, 2007 12:41 am ] |
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I've noticed lately that some of my guitars end up with more fallaway on the fingerboard extension than I would like. Do any of you notice this on your guitars? I usually use a bridge of 3/8" thick and a saddle about 1/8" - 3/16" tall. In order for everything to "jive" the neck has to be angled down on the headstock end, therefore when the fingerboard extension is glued down it pulls it down and creates a little drop off. There is only two ways I can think of to solve this problem. One- try fretting after the neck is attached and maybe I could sand everything level. (It would make nervous though if I had done a lot off inlaying). Two- Give the headblock a slight angle. I use a mortise and tenon type neck joint so my headblock is about 2 1/2" long. The top of the headblock (where to top is glued) and the area that the sides are glued to is usually a 90 degree angle. So if you lay a square on the top of the guitar where the neck goes, it would check out square. But what if I put a slight angle on the headblock so that the top and sides wouldn't be perfectly square? The top would go uphill very slightly. I think this could solve the problem of my fingerboard extension being pulled down. Could it cause other problems? I hope I've explained this so it's possible to understand. One thing I want to clarify. When I say the angle of the top would go uphill. We are talking very slightly. The fingerboard extension would not actually go up at all. It would be compensating for the neck angle so that it would lay perfectly flat and natural on the top and wouldn't have to be pulled down when glued. What do ya'll think? |
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| Author: | LanceK [ Fri Sep 07, 2007 12:55 am ] |
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Hi Colby, I sand a ramp into the guitars top so that the fretboard extension meets the top with not resistance. I also (most of time) fret after finish, so I will glue down the fretboard extension, then level the whole deal. Then Fret. |
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| Author: | burbank [ Fri Sep 07, 2007 1:08 am ] |
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I don't dome the top in the upper bout and the upper transverse brace is not radiused. Here are some links to previous discussions on the topic. link linkk |
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| Author: | Colby Horton [ Fri Sep 07, 2007 1:18 am ] |
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Thanks Ya'll! Lance, how do you sand the ramp? With a jig similar to the the ones in the links posted above? Pat, I don't radius any of the braces above the soundhole either. It's not really an arch or radius problem I'm having. Thats a sideways problem, this is more of a up and down problem. 
Will those jigs put an angled ramp on the top? |
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| Author: | Bruce Dickey [ Fri Sep 07, 2007 1:21 am ] |
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Colby, if you radius your tops as most of us do, yes, the neck block will run uphill toward the sound hole. And, as Lance points out, sanding a landing for the fretboard is a great idea to make it align perfectly. Great question. Adding a shim under the fretboard is not as desirable of course. I've seen that just this week on a beginning builder's work and it's just hard to make it look nice, to say the least. |
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| Author: | burbank [ Fri Sep 07, 2007 1:43 am ] |
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Oh, right. I do what Todd Stock (but with a much less slick jig) and many others do, as shown in the first link in my previous post to get a consistent angle where the fb extension gets glued, as it indexes off the bridge area. Makes sense to me, since we essentially set the neck angle to get the correct relationship with respect to the bridge, then also set the fb extension angle from the bridge. |
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| Author: | Brock Poling [ Fri Sep 07, 2007 1:47 am ] |
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During construction if you lay a straight edge on your neck (w/o the fb attached) is it making perfect contact with the top all the way to the sound hole? |
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| Author: | Michael Dale Payne [ Fri Sep 07, 2007 1:48 am ] |
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My 28' domes on my SJ and OMs seem to provide a near perfect angle of incline but that is totally subject to where the apex of the dome is in relation to the center of the guitar and how perpendicular you maintain the bowl while sanding the rim. In this past I posted a cad drawing of this relationship. However in the hear past I have started leaving my tops thicker in the extension area and started sanding the extension plane as shown in the links above. I am not changing the angle induced but the dome, but rather flattening to a consistent plane. Just knocking of the radial rise till the fretboard plane is flat across the cord of the extension |
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| Author: | Michael Dale Payne [ Fri Sep 07, 2007 1:52 am ] |
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My 28' domes on my SJ and OMs seem to provide a near perfect angle of incline but that is totally subject to where the apex of the dome is in relation to the center of the guitar and how perpendicular you maintain the bowl while sanding the rim. In the past I posted a cad drawing of this relationship. However in the near past I have started leaving my tops thicker in the extension area and started sanding the extension plane as shown in the links above. I am not changing the angle induced buy the dome, but rather flattening to a consistent plane the width of the extension. In other words just knocking off the radial rise till the fretboard plane is flat across the width of the extension |
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| Author: | LanceK [ Fri Sep 07, 2007 1:58 am ] |
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Colby, I use a 4"X6" oak sanding block. I draw lines side to side in the upper bout area where the fretboard will lay, then I start sanding from the sound hole forward toward the guitars top, as I watch the pencil marks disappear, I keep rechecking my fit. Once my marks are gone, the fretboard pretty much lays like it should, providing my heel angle is right. This is all assuming your geometry between your back set and bridge height is correct. After that, I feather in the slight edge you will make by sanding a "flat" in your top. |
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| Author: | Colby Horton [ Sat Sep 08, 2007 2:45 am ] |
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Ah, no wonder the angle has not worked out right for me. I haven't been putting a radius on the sides. Just slightly arching the braces on the top (Cumpiano Style). So, is a 28' the best radius to go with? |
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