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| Stress crack in finish? I need a plan! http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=37150 |
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| Author: | NWflyonly [ Fri Jul 20, 2012 5:26 pm ] |
| Post subject: | Stress crack in finish? I need a plan! |
I have a stress crack on #2 where the fret board meets the top and I need some help on a resolution. I haven't glued the bolt on neck yet and the crack is on both sides. My thoughts were to glue the neck to the body and then carefully sand the crack and drop fill but I'm not sure if that will work. Any suggestions? Sorry about the photo quality used my phone....and it's not one of those gazillion mega pixel camera phone. |
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| Author: | bluescreek [ Fri Jul 20, 2012 5:33 pm ] |
| Post subject: | Re: Stress crack in finish? |
your neck is working up the fretboard extension is fixed you the finish is showing the stress, your bolts may not be tight enough |
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| Author: | NWflyonly [ Fri Jul 20, 2012 5:44 pm ] |
| Post subject: | Re: Stress crack in finish? |
John thanks for the input I checked the bolts and they are mighty tight. What is occurring is that the fret board extension is curving down into the top so when attached and bolted the extension pushes upward as the bolts are tightened and it puts stress on that joint. |
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| Author: | Tom West [ Sat Jul 21, 2012 5:39 am ] |
| Post subject: | Re: Stress crack in finish? |
Mark: How does the board look in that area with a straight edge placed on top of it while the neck is on the body? Tom |
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| Author: | NWflyonly [ Sat Jul 21, 2012 10:46 am ] |
| Post subject: | Re: Stress crack in finish? |
Tom West wrote: Mark: How does the board look in that area with a straight edge placed on top of it while the neck is on the body? Tom It looks just fine laying nice and flat in line with top and my neck angle looks good relative to my bridge. What I've found is that when I fret up the fingerboard prior to gluing to the body the extension inevitably curves downward, it happened on my last build. Part of me believes that if I glued up the neck/fret board to the body prior to finish I would eliminate this problem. I've never done it that way but perhaps that's my next approach. However, I'm in need of a solution to what I have at the moment. What do you think about the approach I mentioned in my previous thread? |
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| Author: | Tai Fu [ Sat Jul 21, 2012 11:22 am ] |
| Post subject: | Re: Stress crack in finish? |
I recommend installing the frets only after everything is in place, neck bolted/glued in, etc. unless you have a full length supported fingerboard like on Taylors. These movement of the fingerboard invariably creates a hump at the body joint especially if there's a downward bend at the fingerboard extension. You can resize the fret tang when hammering in the frets at the extension to make things a little easier... |
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| Author: | Tom West [ Sat Jul 21, 2012 6:29 pm ] |
| Post subject: | Re: Stress crack in finish? I need a plan! |
Mark: I'm assuming the finish crack is between the fretboard and neck. That makes me wonder is you have some seperation between of the glue line between the board and neck. At one time I would install neck and board to body before fretting but for quite a while have been using a mortice and tenon and fretting the neck before installation. This will cause a very slight downward curve on the extenion but nothing that can't be very easily removed at installation. If you used tight fitting frets,you should have gotten some back bow that was pronounced. Also extra in the extention that would make gluing it down somewhat more troublesome. But I can't imagine it would be enough to cause you your problem. This causes me to wonder about the glue line. I wonder if you used epoxy glue? Sometime you can get in trouble with epoxy and too much clamping pressure. Tom |
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| Author: | NWflyonly [ Sat Jul 21, 2012 6:58 pm ] |
| Post subject: | Re: Stress crack in finish? I need a plan! |
Tom West wrote: Mark: I'm assuming the finish crack is between the fretboard and neck. That makes me wonder is you have some seperation between of the glue line between the board and neck. At one time I would install neck and board to body before fretting but for quite a while have been using a mortice and tenon and fretting the neck before installation. This will cause a very slight downward curve on the extenion but nothing that can't be very easily removed at installation. If you used tight fitting frets,you should have gotten some back bow that was pronounced. Also extra in the extention that would make gluing it down somewhat more troublesome. But I can't imagine it would be enough to cause you your problem. This causes me to wonder about the glue line. I wonder if you used epoxy glue? Sometime you can get in trouble with epoxy and too much clamping pressure. Tom Tom you're right about the separation it must be a weak joint and not enough glue and/or clamping preasure? I don't use epoxy I've been using tite bond I think I might take a look at hide glue. The curvature in the fret board extension was enough to probably stress that joint when I glued the neck to the body. I think on my next build I'll fret all but the extension and glue it up followed by the extension fretting once everything has set up. Any repair solutions? |
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