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  #16  
Old 08-29-2014, 01:03 PM
mgeoffriau mgeoffriau is offline
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Going to attempt the repair soon -- my bottle of Titebond original arrive yesterday and the glue syringe should arrive in a few days. I've been thinking about how to best approach the repair, and the part I can't figure out is how the guitar should be positioned.

If I have it lying on its back, gravity will be working against me trying to get the glue into the cracks. The best position I can envision is to have the headstock pointing straight down, so that I could reach into the soundhole with the syringe, and direct the glue onto the brace below. But I'm not sure how to safely hold the guitar in that position. Perhaps just hold the neck firmly between my legs, then move it back onto the work surface after I've applied the glue?
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  #17  
Old 09-02-2014, 09:10 PM
mgeoffriau mgeoffriau is offline
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Started the repair tonight -- attacking the separation between the brace and top first. I wedged a toothpick in there to open it up as much as I could, then used a glue syringe to put a good bead of glue along the seam. I then took a couple more toothpicks and tried to "stuff" the glue underneath the brace as much as I could. I held the guitar upside down for a couple minutes to let the glue seep under the brace, then clamped it with the craft sticks I'd already trimmed to length. The guitar is now resting propped up with the soundhole side down, and the neck angled down, to keep the glue along that seam.

I'm still worried I didn't get enough glue underneath the brace -- you can't see what you're doing while you're doing it, and I couldn't get the separation open very far. I guess if it opens up again after I remove the clamps, I'll just try again.

Any recommendations on how long I should wait before unclamping and starting the repair on the crack in the brace? Is 24 hours sufficient?



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  #18  
Old 09-04-2014, 03:33 AM
John Arnold John Arnold is offline
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It looks to me like you got plenty of glue in there.
Since the top was sunken and the joint spread open, I would wait at least a couple of days before removing the sticks.
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  #19  
Old 09-04-2014, 10:17 AM
mgeoffriau mgeoffriau is offline
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Quote:
Originally Posted by John Arnold View Post
It looks to me like you got plenty of glue in there.
Since the top was sunken and the joint spread open, I would wait at least a couple of days before removing the sticks.
Oops -- didn't wait a couple days. I did wait a full 24 hours, and when I removed the sticks, there was no sign of the brace separating from the top. It was only unbraced for about 15 minutes while I glued the crack in the brace and then reinserted the craft sticks.

I'll confess I made a bit more of a mess the second time around -- the open crack and the difficulty see what I was doing meant I got a bit too liberal with the glue and it dripped a few places inside the body. I did my best to wipe up the excess, but I was worried I would knock the braces loose so I may have missed some spots.

I guess that's why it was good I started with an $85 beater -- if there's some glue spots inside, it won't bother me.
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  #20  
Old 09-05-2014, 05:03 AM
John Arnold John Arnold is offline
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You can use a rag wetted with warm water to removed dried glue. That is the beauty of using Titebond Original (or hot hide glue).
It will take longer than if you had removed it before it dried, but patience will win out.
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  #21  
Old 09-05-2014, 05:59 AM
Earwitness Earwitness is offline
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Well, you've now got about $1000 of the best luthier advice possible invested in that $85 guitar! Just kidding! This is the kind of thread others will refer to in the future for the same thing.

Hope it sounds great--you are probably going to love it and start buying every cracked guitar you find.
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  #22  
Old 09-05-2014, 06:16 PM
mgeoffriau mgeoffriau is offline
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Updates!

So, things I have accomplished:

1. Gluing the brace back to the top, and then gluing the crack in the brace. I gave the glue 24 hours between each step. As you can see, I got a bit gloppy with the glue while I was repairing the crack. I will probably try to clean up the worst of the excess glue blobs, but I don't anticipate spending a lot of time on it. I did it, I learned from it, and I'll be more careful if there's a next time.

In other news, the craft stick braces worked great, but they definitely have a limited life. It's difficult to cut the notches without starting a lengthwise split in the grain, and then when you wedge them into place, the pressure makes them want to split even more. I made 3 really good ones, and they lasted for the 2 repairs, but by the time I removed them the second time, only 1 of them was still reusable. Fortunately they are cheap and easy to make.

Despite possibly using too little glue on the first half of the repair, and too much glue on the second half, everything feels solid. Hopefully it'll stay together when it's strung up to full tension.





2. I also fixed the little damaged piece around the soundhole (3rd pic in the 1st post). No pics of the repair, but I basically just used a toothpick to dab a bit of glue underneath the separated piece, and then clamped it shut with a small Irwin Quick Grip and two small pieces from a craft stick to protect the wood. Came out great.

3. I decided that if this was going to be an educational project, I may as well attempt to repair the cracks in the poly finish as well. I got some clear liquid CA glue, and dabbed it over the cracked area with a toothpick. It looks pretty bad now, but I figured since I'll be wet-sanding and polishing the area down flat, it would be better to make sure every crack was completely filled. I will probably use a taped-up razor blade to scrape down the high spots before I start sanding.

Any thoughts on how long I should allow the CA glue to harden before attempting to scrape or sand it down? I have plenty of time -- my sandpaper and Micromesh probably won't arrive for 2 or 3 days.



4. In between the other steps above (read: while waiting for glue to dry), I also sanded down a compensated Tusq saddle to replace the plastic Yamaha saddle. The plastic saddle was quite high and also pretty loose in the bridge. I got the Tusq saddle to slide smoothly into the bridge with just a hint of snugness, and brought it down about a millimeter lower than the Yamaha. I have some bone saddles on the way, so if the Tusq saddle ends up being too low, or I don't like the tone, I'll start over with a new one. No pics.
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  #23  
Old 09-06-2014, 05:38 PM
redir redir is offline
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I would not worry about trying to clean up that Titebond, it's not going to be easy and it really doesn't matter. The time to do is is as JA said when it's still wet adn with a damp cloth. I did notice in one of your pics that the wood splints had split and I did wonder about the integrity of it. Maybe next time you can use some CA and glue some braces on to the splints, just a cleat right where the V of the notch is ought to do it I would think.

CA finish repairs can be scraped after an hour or so. I like to get it when it's still sort of soft and then let it harden over night and finish it with a scraping tool and papers. But a big blob like that is best hit with a chisel when it's in the rubber stage.

In any case you did well on your first repair
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  #24  
Old 09-06-2014, 09:20 PM
John Arnold John Arnold is offline
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I have never felt the need to cut vee notches in the ends of the prop sticks. To get the proper length, I just clip them square across with my fret pulling flush end nippers.
Quote:
Any thoughts on how long I should allow the CA glue to harden before attempting to scrape or sand it down?
Hardening time varies a lot, so the only way I know to test it is by pressing it with a fingernail, or by gently scraping it to see if it fuzzes up....meaning it is still soft.
If that happens, I shoot it with CA accelerator. There is a risk that the CA could foam and turn white, but if you wait long enough before using accelerator, the risk is minimized. The CA I use is odorless, and is much less likely to foam when using accelerator.
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  #25  
Old 09-08-2014, 09:35 PM
mgeoffriau mgeoffriau is offline
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Tonight I worked on sanding and polishing down the CA-glued cracks in the top.

Surprisingly, the razor blade trick did not help at all. Even when I rolled the edge to get a tiny burr on one side, I couldn't get the edge to "grab" on the top of the CA glue...it just slid right over it. After a few attempts, I got worried that I would have to apply too much pressure to get it to scrape any glue off, so I abandoned the razor blade and moved on to the sandpaper.

I wet-sanded using 3M 220-grit, 400-grit, 800-grit, and then 1000-grit. At that point, I switched to MicroMesh and wet-sanded/polished up to 12,000-grit in several steps. This technique worked pretty well.

I had a couple problems. For one thing, if you go back to the first post, you'll see that the edges of some of these cracks are quite raised. This meant it was really difficult to get those high points leveled down without going all the way through the poly finish, and...sure enough, you can see a light spot where the poly finish wore through. The area isn't perfectly level, but I was hesitant to work the area much more than I did. To do a really top-notch job, you'd have to shoot that spot with another finish layer so that you could sand it all evenly, and that's beyond my skill/budget.

Secondly, I couldn't quite get rid of a very faint, white haze over that spot. Again, I was afraid of over-working the area, so maybe with some more polishing it might go away. If I get bold, I might try again from about midway through the MicroMesh grits and see if I can get a really clear gloss finish, but I'll probably leave it alone. It's only noticeable if you're looking for it and it catches the light just right, and after all, it is a beater guitar.

I strung up the Yamaha with some Pro Arte's this evening and I'm quite pleased with the outcome. The new tuners work great and look even better, and while the improved sound is probably 90% the result of the fresh strings, I'd like to think the repaired brace and new saddle are contributing a little bit as well.







Anyway, I wanted to thank everyone that contributed with advice and ideas. I really enjoyed the project and have a new-found respect for luthiers.
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  #26  
Old 09-09-2014, 08:09 AM
charles Tauber charles Tauber is offline
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Quote:
Originally Posted by mgeoffriau View Post
Surprisingly, the razor blade trick did not help at all. Even when I rolled the edge to get a tiny burr on one side, I couldn't get the edge to "grab" on the top of the CA glue...it just slid right over it.
Scrapers need to be held very near vertical (perpendicular to the scraped surface) to work. Chances are, the angle at which you held the blade was too low resulting in it just sliding over the surface to be scraped. Scrapers, of all sorts, are wonderful tools, useful in many applications.
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  #27  
Old 09-09-2014, 01:04 PM
Ned Milburn Ned Milburn is offline
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As John says, glue squeeze out and spills can be cleaned with a damp cloth, but you can also scrape dampened glue with a small cabinet scraper. It must be held quite firmly to scrape properly without damaging the wood underneath.
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  #28  
Old 09-09-2014, 04:33 PM
Halcyon/Tinker Halcyon/Tinker is offline
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Well done!
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