"How To" Crack Repair
Copyright 2016  by "Musical Instrument Repairs WA (MIRWA)"             All Rights reserved    E-Mail: service@mirwa.com.au
Crack Repairs are a staple of the business, its a daily repair process.

The idea is to try and reverse what has happened

Time to repair approx 2 hrs over 2 days (glue drying times)
The steamer.

Wood grain is held together via natural glue (Lignin), this natural glue binds the wood as it grown, when an instrument is broken and fractured, we need to soften the natural glue so we can manipulate the grain where it needs to be.
Using sound hole clamps and our steamer nozzle we slowly bring the surfaces back together.
Because its a full length crack all the way back to the rear edge, we need to re-inforce it on the inside.
We trim and shape a piece of spruce with the grain running the opposite way for strength
Getting our length pre trimmed
After 24hrs, remove clamps.

We are using a mirror to view the underside of the top, the circle shows the fitted cleat.
This Ukelele has been dropped against a hard surface, which has punched a hole into the top. It has a deep impression area, which has created a crack across the grain, it has also split the top from the bridge to the butt.
As we will be putting clamps inside, its best to remove the electronics, this way they do not get damaged.
A steamer softens / or loosens that glue bind.
Our clamping tools, two soundhole clamps, a curved caul and some titebond.
This clamp has been mocked up to show what the system will look like, the clamp pushes on a caul which holds the piece of spruce.
Clamped and glued, allow 24 hrs glue dry time.