Top Crack Corrector

A new system that combines modern technology with old school materials

(2 customer reviews)
Clear selection

These feather-weight (less than .8g), thin (.055), super strong cleats are the heart of this new system. Combined with installation cauls and strong magnets, they allow you to glue both the crack and the cleat in one operation. Once everything is located and aligned, the cleat can be installed perfectly in less than 60 seconds, making hide glue a viable option. The grain is oriented at an angle (matching that of prewar tone bars), which is about the only thing they have in common with their earlier predecessors, the diamond and disk cleats. If you ever need to uninstall the cleat, it can quickly be removed (if glued with hide glue, other glues will take longer) by laying a warm damp sponge on it. Within a few minutes, you’ll be able to lift the cleat out. Any residual hide glue can be removed with warm water and a small sponge.


You may want to map out the location of top braces until you get the hang of this new tool. I use magnets to make this job more interesting and fun. Tape a piece of masking paper (available in paint dept. at the Home Despot, etc) on top of the guitar. Then, using a magnet inside and a matching magnet on the outside, move them around, bumping up against all braces and marking location on paper until you can connect all the dots. When finished, mark paper with make and year of instrument, roll it up and store it for future reference.

This kit is designed for truly flattop instruments. It is not meant for guitars that have greater arching in the top, such as many early Gibson guitars.

Since the invention of the acoustic guitar, we (flattop/back repair peeps) haven’t had a crack repair method that was designed for and suited to our needs. Thanks to the advent and availability of neodymium (extra strong type of rare earth) magnets, now we do. Previously we had adapted and adopted the diamond and disk cleat method commonly used and ideal on carved orchestral instruments. Unfortunately, it is not ideally suited to our needs. We can’t just pop a top or back off and on! We make every effort to install cleats straight and on the crack, but even if we succeed, we are only reinforcing one small section of the crack at a time. As each short section of cleat dries in place, we often see shrinkage in the reflection in top (?) where each cleat is located.

Video from stewmac.com

2 reviews for Top Crack Corrector

  1. Pat DiBurro

    Diamonds are not forever!
    Ok, full disclosure. I have been using the Thompson Crack corrector for several years now ever since TJ sent me a prototype. Prior to this new system I used the traditional diamond cleats working blindly through the soundhole hoping the cleat straddled the crack line before the hide glue gelled.
    The genius of this new design is that as the product name implies an older crack that has flared upward or is fractured can be realigned flush by means of a continuous petite cleat, quickly and accurately.
    Dan Erlewine’s instructional video demonstrates some common cleating techniques and with the benefit of a few years in action I would add that the blank cradle supplied with the kit is vital. I have cut those blanks into small sections, drilled 1/4” holes and installed additional magnets creating cradles for small crack repairs.
    I marked the precut cradles with a letter and made a chart showing which cradle works for a Martin D, or size 0 for quick selection of the right one. Also when cutting a blank cradle for a different bracing pattern it is marked and noted on the chart.

  2. Steve Kovacik

    perfect tool for the job
    I’ve used this system for numerous top crack repairs with excellent results. As with any tool there is a learning curve but I found the tool to be easy to use effectively. I like the fact that the system clamps the crack flat and installs the reinforcement strip in one operation, which is an improvement over a two step process of gluing the crack and then installing diamond or disk cleats. Saves time, which is important in a busy repair shop. The reinforcement being one continuous strip is also an improvement to individual cleats. The magnetic feature assures proper and easy placement of the reinforcement and caul. The blank caul that is supplied allow you to cut for bracing arrangements that the pre-cut cauls won’t accommodate. In my opinion the price is reasonable, as it would cost any craftsman $125 worth of his time to create the same set up and put it into use. This is a great tool for the pro or hobbyist that will improve your results.

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