This Les Paul came into the shop recently with a particularly bad neck break. The neck had been broken before and splines had been added to strengthen the repair but the splines were broken as well. An attempt to glue the neck again proved too weak for the string tension and the crack is visible through the new finish. In a case like this, where the glue line is either too short or a repair has already been unsuccessful, a backstrap is a good option.
To get as much strength out of the repair I wanted to replace the splines. I set up my Sherline mill column on the X-Y base to closely remove the old broken splines and replaced them with new maple ones. Then, using a Wagner Safe-t-planer I removed material from the back of the headstock, about 2/10 of an inch, and blended it into the neck. The ideas is to glue a bent piece of mahogany with continuous grain across the broken area. Here I have sandwiched two pieces of mahogany to make up the thickness needed.
Once sanded an finished the repair is barely visible and very strong.