Acoustic Fixing an endblock crack

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Here’s a crack that happens when the guitar gets a heavy hit on the end pin. It can happen when the guitar is in a gig bag, or even inside a hardshell case. This one is a shipping injury.

The crack in reflected light

The crack in reflected light

This is a crack in the endblock, a pretty nasty crack. In this photo, I used the reflection of the lightbulb to help point it out. This one is subtle, but they’re notorious for spreading along the grain lines if left unattended.

Here’s a shot of the inside of the guitar, with a little liquid dripped through in order to illustrate just how deep it goes. (This liquid evaporates)

Inside view of tailblock crack with naphtha.

Inside view of tailblock crack with naphtha.

The first step is to open up that crack in the block so we can get glue into it. A long clamp with just a little pressure going from the neckblock to the end block is a good way to do this, with a small caul parallel to the crack to wedge it open from the outside.

Long clamp puts pressure on the block to open up the crack for inside access.

Long clamp puts pressure on the block to open up the crack for inside access.

Closeup

Closeup

Here’s what it looks like now on the inside.

Open crack, inside view.

Open crack, inside view.

Now that it’s open, we can get some glue into there. With a long pipette filled with titebond, and a long palette knife, (and a twisted elbow) it’ll start to look like this :

Initial gluing, inside view.

Initial gluing, inside view.

Now when we remove the outside clamp, the crack closes up and it’s ready to clamp up. The two parts of the broken block need to be aligned. We used a threaded rod through the endpin hole to do this, with a nice big washer on the inside to pull it flat.

Inside view with squeeze out.

Inside view with squeeze out.

 

 

The outside has a large clear acrylic caul with another washer and a nut to tighten it all up.

001-tailblock-007

Then we clamp the block the other way, from the top to the back with two cork topped cauls and wax paper to prevent any finish damage.

 

After that’s dried and unclamped, I did four coats of laquer touchup to make it look like nothing happened.

Lacquer applied, sanded buffed and ready to go!

Lacquer applied, sanded, buffed and ready to go!



Written By James Hingston

James has slowly been working his way westward for years. He was born in England, but grew up mainly in Vermont. His foray into guitar repair started when he and his Dad swapped the pickups in an old Hagstrom, and ever since he’s had the bug.

He built some solid…

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