I received a guitar for repair yesterday that I have mixed feeling about. It is an inexpensive (Dean) acoustic that has a crack starting at the bottom of the nut slot that has propagated about 1" toward the body of the guitar.
The crack is closed under string tension. I loosened the strings and the crack widens when moderate pressure is applied to the face of the headstock but closes up when pressure is removed. Tuning is stable. The guitar has other issues resulting from mechanical trauma in other areas (cracks in top and sides)
I'm inclined to leave the crack alone at the moment because I can't open the crack enough to flow glue far enough into it to make a sound structural bond. The neck appears stable and - short of another blow to the headstock or prolonged exposure to heat - I don't think the crack will get any worse. If it does - a proper repair can be.executed at that time.
Will get photos posted later today.
Thoughts and suggestions would be appreciated?
Sometimes when we are concerned about getting glue way back into a crack that can be pried open a bit but wants to remain closed on it's own two techniques come to mind:
1) It's always an option to push some Titebond original in there as far as you can with feeler type gauges AND then use compressed air to help the glue migrate further into the crack. When using compressed air use a limited spray or it can blow all of the glue out all over ya.... Don't ask me how I learned this....:)
2) I've never done it but I was impressed by a post I read by Rick Turner around 10 years ago where he indicated that he injects hot water into some cracks and the water acts as a carrier to help the thicker viscosity HHG migrate deep into the crack. Of course all clamping has to be close at hand and the crack needs to close well on it's own which is what it sounds like you have here, JR.
Sometimes clients don't have the budget or are not willing to cough it up with certain instruments where certain repairs may not make economic sense but they can save the functionality of the instrument if done anyway. Either of these methods might get it fixed (structurally) with very little effort and might be a nice surprise for a client such as this.
What Hesh says and: Flatten out a 21 (or so) gauge hypo needle (smooth jaws in a vice works well) clamp the neck and use a speed clamp to gently open up the crack to get the needle into the crack. Massage the excess glue into the crack with yr fingers and open and close the crack a few time while repeating the dose - this helps to capillary the glue deeper into the blind part of the crack.
Secondly, if you cannot do this due the tightness of the crack or the feeling that opening a crack up may prove problematical just put a pit of pressure on it after masking up with brown shinny packing tape and give it a drink of CA (superglue), take the pressure off, clamp shut and wipedown. Superglue is fine for this particular guitar application.
I personally do not leave any crack unattended as they only get dirty and get worse.
Here's a description of a super cheap, customizable glue applicator I use to get glue into the deepest parts of a headstock crack. Although it's not impressive looking, it gets the job done correctly and with a great deal of precision. Lots of clean-up of excess glue, but what the heck, eh? I'll answer any questions if anyone wants to make/use them.
Anyway, this device would be perfect for the task at hand. The flexibility of the shrink tube applicator is the trick to this device.
For the good of all mankind:
Paul, Have you considered using two, thin feeler gauge blades with the glue squeezing out between them?
Hiya Ned :)
Yessir I have.
I'm sure everyone with experience recognizes this design as an alternate take on one of Dan E's tools. It is NOT an original design.
Designed to be used only when I can spread apart the break, the unique thing this device offers is an extremely flexible feeder tip that will negotiate any grain related hills & valleys in the break. That's the only & major difference. Being flexible, it can be 'jammed' all the way into the back end of the crack without being impeded by the topography of the break.
Depending on the length of the break, I've made the shrink tube feeder tips from 1/2" long to 4" long. I buy my syringes at the local Equine/Farm Supply house. Quality BIG syringes at dirt cheap prices. There's a Medical Supply store in town and I dumpster dive their store for UNOPENED packs of clear vinyl tubing used in CPAP machines. I may have acquired a lifetime supply ;)
I wouldn't use it for brace repair as we'd definitely need an inflexible applicator that does double duty as an spreader shim.
I only use Titebond with this rig. It cleans up easily with hot water. It fills my frugal goals of : It's EASY, It's INEXPENSIVE and (most importantly) It's EFFECTIVE :)
Hope that explains it better. Have a good'un, Ned :)
Excellent suggestions Paul!
wow Paul, that's a really cool device. Do you have pictures??
I'll whip one up & get a photo or 2 as soon as possible.
Thank you & Mark for the kind words.
Nice Paul !!!
I did this kind of repair on a cheap acoustic recently. I taped up around the neck (using cloth + tape) to support the neck where it isn't cracked To avoid opening the crack even more). I then slightly opened up where the crack was & inserted a small amount of general wood glue diluted with one 4th water (to get it in there). I then clamped it for 24 hours. The crack was/is visible but you have to look for it and the guitar has been fine ever since. In fact, I sold it on eBay for it's going rate...
I would like to float another idea.
More and more I am flowing thinned hide glue into things.
There is not much of a down side to overly thin hide. If there are insufficient solids on the first go-round, it just becomes sizing for the next.
I have experienced, along with many in the violin repair crowd, hide glue not holding on the first application but holding like the devil, on the second or even third application.
Rick Turners method of pre-wetting just nets you the same thing as thinned hide in a less controlled way.
Set the instrument so gravity is on your side, warm gently with a heat lamp or gun, and run some really thin stuff into the tightest pat of the crack. You can follow it with normal viscosity on the more accessible end. thinning slows the gel time and, as the wood pulls away moisture, more can be added to up the glue solids before it must be clamped.
I find with warming and thinning I can get hide glue deeper than anything except thin CA.
Violin tops are held on w/ a thinned hide glue solution to facilitate future removal. I think most would be amazed at how thin it must be before it stops ripping all he wood with it when testing on scrap. Try it.
I would rather tell customers I can give it another shot,(even if the headstock came all the way off in the future) Than say, if this fix fails your instrument is toast. Or worse yet, fix a failed headstock repair with AR glue in it on my dime.
Not to say there are instruments that are not worth the effort of a second try.
You sure it isn't a scarf joint opening?
IMO if you can flex it and see it opening, you can and should glue it. Of course, the decision is the customer's once she hears the price.