Sanding Yamaha cracked neck repair

[Jmackay66]

I have a Yamaha fg700s that has a crack on the bass side of the neck, running parallel to the fretboard binding, from the nut about 3" straight along the edge of the binding. String pressure holds the crack shut. If I loosen the strings, I can gently spread the crack open. There is no damage to the binding itself. I believe I can spread the crack open, work some titebond into it and clamp it. Nothing seems to be tweaked out of shape, so I think I'll be fine with the repair. It also cracked the gloss finish on the neck around the damaged area. Is it ok to sand that area with fine paper to smooth it before the glue up? Owner doesn't care about aesthetics as long as it's smooth. So I don't have to worry about refinishing. Any suggestions would be appreciated.

[mirwa]

Sounds like a typical face plant crack.

Steve

[redir]

Don't sand it prior to gluing it. If anything you want to sand everything smooth after gluing it. Without seeing pics it's hard to say but it sounds like what you want to do is glue it up and clean up the squeeze out real well then just drop fill or partial refinish the area then sand and polish out.


Edit: Just read Steves post, that about covers it. But if it's just chip out poly (my guess) and you don't care too much about looks you can drop fill and level with CA. In the end even that looks good enough for most people.

[Jmackay66]

Ok, looks like some of the poly around the split is loose, like I could take an exacto knife and flake it off. Should I do that or just sand it all smooth after glueing? And, if it's a poly finish, can I use clear poly spray can to finish it a bit? Thanks in advance, very helpful so far.

[phavriluk]

If OP can get some movement between the fingerboard and the neck, his instrument's problems aren't just cosmetic. Stew-Mac just put up a video of a repair to the binding and top on Willie Nelson's guitar; it might be worth watching. The problem is not in the same place as on his, but repair might be instructional.

[John Arnold]

Clear poly spray is polyurethane. Most Asian poly finishes are polyester. Two different finishes. I generally touch up polyester finishes with super glue or lacquer.
Rather than an impact directly on the peghead, most of these cracks are caused when the guitar case falls backward, particularly during shipping when the strings have been loosened. The impact shocks the peghead (whiplash). Momentum, which is increased with heavy enclosed tuners, is the cause.
Another factor is the case design. A neck cradle near the nut helps prevent this damage. Cheaper cases have a neck cradle near the body, and don't support the peghead area as effectively.
As a result, I don't loosen the strings all the way when shipping, and I always pad the back of the peghead as well as the front.

[Jmackay66]

Thanks for the reply on the poly, JA. I have the neck glued. It looks good and is stable. Going to drop fill the missing poly with ca. Watched a couple drop fill vids on yt. I'll try to soften the edges first then fill in layers till fill is just a tad high, then scrape level with razor blade, sand and buff. This is my first attempt at this, so hoping it comes out decent. Thanks again!

[murrmac123]

Originally Posted by John Arnold

Rather than an impact directly on the peghead, most of these cracks are caused when the guitar case falls backward, particularly during shipping when the strings have been loosened.

I don't loosen the strings all the way when shipping, and I always pad the back of the peghead as well as the front

Totally agree that these cracks are in fact caused by damage in shipping ...(I had to google "face plant" ...new term for me ...LOL ...)

I have had this happen to me before, on a Collings which was shipped to a customer by a second party, and the memory still hurts.

100% agree on the padding of the headstock (back and front), John, but I fail to grasp why you think the strings should not be totally de-tensioned ?

I know that Jean Larrivee thinks the same as you, btw, but I have yet to see a reasoned analysis of why exactly a guitar which is shipped with the strings under tension is less likely to suffer headstock fracture than a guitar which is shipped with the strings totally loosened.

The critical factor, IMO, is the quality of the padding of the headstock prior to shipping.

[mirwa]

Originally Posted by John Arnold

Rather than an impact directly on the peghead, most of these cracks are caused when the guitar case falls backward, particularly during shipping when the strings have been loosened.

I do agree that whiplash situations occur, I would dis-agree most neck splits behind the fretboard occur from shipping, in my locality it would be the odd one out, most (95 plus percent of the ones I see) are from having fallen over and taking a direct hit to the machine head area, I know this from the customer telling me how it happened.

I have four broken headstocks in this week, two with this exact break at the moment. Both received hits into the machine heads, neither was a shipping issue, as I mentioned before, these types of cracks being attributed to shipping are more the unusual situation that I find in my locality.

Steve

[Jmackay66]

Well, repair is done. Came out better than expected. Glassy smooth and only slight discoloration where old finish flaked off. Very happy with it. I'm amazed that super glue works like that. I scraped it with a razor blade. Then sanded 600-1000-2500, then rubbed out with fine cut polishing compound. Glossy good. Thanks again for the advice. Much appreciated.

[mirwa]

It is a good feeling when things go to plan.

Steve