Guitar Body Cracks
Source:Crack & Brace Repair
Top – Open Miss-Aligned Crack Repair:
As with Hairline Crack Repair, Open Cracks in spruce tops are some of the most difficult cracks to repair. The reason for this is because of the light wood. Most of the glues that are available today dry with an amber or yellowish color and this shows up immediately on a light Spruce Top.
If the wood has darkened with age, you are lucky and you can use either Titebond or a 2-part epoxy glue for these cracks. If not – you should stick with a bottled hide glue, which drys to a much clearer appearance.
Add to this the difficulty of dealing with a miss-aligned crack and you can have your hands full. Come to the rescue the Crack Alignment Jig. We have discussed this jig in our previous article on how to make the Crack Alignment Jig. If you desire to have a free download plan of this jig, please visit our Plan Shop. Just scroll down to the Free Plans portion of the page at the bottom and click the download link.
Using The Crack Alignment Jig:
With an open, miss-aligned crack, we are dealing with a different animal. Our first order of business is to get the two sides of the top back into alignment, before we can really deal with the crack repair.
Depending of the length of the crack, you will have to prepare several alignment jigs at once. I like to space them at about 2″ o.c., so I usually have 3 to 4 of them handy. Be sure to wax the bottom of the jig so it does not stick to the guitar top. Do the same with the patch caul.
I like to use a light E or 1st string guitar for this jig. I clip off the ball above the winding and take a needle nose pliers and make a couple of small loops at the bottom of the string. Then I take solder and place about a 1/8″ ball of solder on this loop.
Prepare you cross patch. See the article on Hairline Crack Repair for instructions on making these patches. Apply a bit of glue to each end of the diamond-shaped patch an orient it correctly. Sometimes for difficult areas, I will use a small piece of double stick tape to hold the patch in place.
Thread the patch and the caul with the string and poke it up through the crack. Start at one end of the crack and progress to the other end with subsequent patch jigs. Slowly tighten the jig, while holding the caul with your other hand through the sound hole. Just snug it up a bit until it seats firmly in place. Now do the same with additional jigs, until you have reached the opposite end of the crack.
Our goal here is to minimize glue from getting into the crack, as this will need to be cleaned out before our next step. Set the guitar to dry overnight.
Tip: You may want to start this by using a slower set 2-part epoxy to give you more open glue time to get everything set. I do not prepare more than 2 jigs at one time as you are madly working to get everything setup and tightened. A bit of extra time is welcome if you run into a problem that catches you off-guard – like a string break on a jig.
Cutting Through The Crack:
The next thing we have to do is to cut through the crack with a saw blade. We want to be extra careful at the patch areas, that we do not compromise their integrity. Try to have different gauged saw blades in stock so you can use one of the proper thickness to saw out the crack. These can vary from about .010″ to .030″ in thickness.
When you have selected a blade that will shave just a whisker of wood off each side of the crack, saw through the top the entire length of the crack. Be sure to navigate around any top braces you may encounter, and of course the cross patch that have been glued in place..
When you approach the ends of the crack, leave a ramp in the cut by angling the blade at 45 to 60 degrees.
Preparing the Splint:
Rather than repeating everything once again and shortening an already long article, the remainder of the operations from Preparing the Splint, gluing it in place and final trimming, is exactly the same as the article Top Hairline Crack Repair. So please refer to that article for those detailed instructions.
Glue Cleanup:
Clean off the bottom of the crack area with fine sandpaper. Remove the tape from the top and carefully cut the top of the splint down to the top surface. If a bit of refinishing is in order, scrape the top of the splint to below the guitar top finish, along with some of the guitar top varnish or lacquer. We will then feather the finish of the splint area with the existing guitar finish area.
Apply Patch Reinforcements:
This was covered the the Top Hairline Crack Article and you should read the detailed directions there for the procedure. Be sure not to space your patches out more than about 1-1/2″ to 2″ to provide adequate top reinforcement.
Finishing:
We will cover the proper way to finish the crack repair area in the article Finishing Crack Repairs, since there are so many different kinds of cracks to address.
Tags: closed guitar crack repair, fixing cracks, guitar top crack repair, guitar top open miss-aligned crack repair, how to fix a guitar crack
