Ultimate Guitar Repair » Blog Archive

Side Crack Repair

March 24th, 2010

Side Crack Repair
Source: Crack & Brace Repair

Side Crack Repair:

Side cracks are a different animal. The reason for this is that they can often be severe and out of alignment and very difficult to repair. The reason sides crack is most often from a blow to the side of the instrument. If left unchecked the crack can easily progress from a small crack all the way to a crack from the Head Block to the Tail Block, or at a minimum from the Block to the Waist of the guitar.

Some guitar manufacturers have provided measures to prevent cracks from spreading by using side reinforcing. C.F. Martin has used and still use cloth reinforcement strips that extend from the top of the back lining to the top of the top lining. Others, including myself, use wood reinforcing or small bracket type bracing and this works well also.

The Reason These Crack Progress So Quickly:

The reason these cracks get severe in a short amount of time is because there is a tremendous about of tension placed on the guitar sides. The force of the strings, pulling upward on the top and the counter-action of the neck heel pulling in the opposite direction cause the sides to be placed in constant tension. Sometimes just a moderate or light bump against the side can cause the side to “pop” and away we go.

Spool Clamp Plans
Source: Crack and Brace Repair

The Quicker the Better:

It is key to try and catch a crack as soon as it is noticed. This is the best and easiest time for the repair. Minor side crack repairs can be handled by a simple glue and clamp operation.

Gluing Minor Side Cracks:

If you have a crack that is rather minor in nature and one that is not out of alignment, simply mask off the guitar side with painters tape, as close to the crack as you can get. With exotic woods use a 2-part epoxy glue and work the glue into the crack with your finger.

Next, depending of the crack length, put spool clamps on the guitar side at about 2″ O.C. or, if you like you can use a double spool clamp for this operation. This works well for cracks in the 4″ to 6″ range.

Spool Clamps:

If you don’t have spool clamps, I have put together an article on how to make both single and double Spool Clamps. They are handy for side crack gluing and for securing a loose top or back too. Check out my Spool Clamp article. Also, I have provide you with a free PDF download for Spool Clamp Plans at our Plan Shop so you can get the exact template for the Spool Clamp construction.

The Final Steps:
Finally, once the clamping is complete, it is time to cleanup the glue. Of coarse with Epoxy glue you will need to clean with acetone on the inside. As for the outside, the masking tape take care of most of the mess, cut try to clean up with a sharp chisel and let the glue dry. You may need to do a bit of finish touch-up work as the final operation.

Tip: If the crack is slightly out of alignment you can make use of the Crack Alignment Jig. This can be used in-between the spool clamps to straighten and re-align the sides. That is where our Crack Alignment Jig comes into play. This jig will allow you to align the crack and reinforce and glue it at the same time. Although if we are talking about just a small alignment problem, reinforcement will not be necessary.