MIMF

How much clamping pressure did you get? T.J.'s cauls are so strong you feel like you cannot pull them directly apart. You have to twist the outside caul to get it to come free.

You did a great job shaping those bridges, Paul. Freehand or belt sander?

A new bridge is needed due to the holes and the crack. I can send you a BRW blank if you want to go that route. I would need your minimum dimensions and you can PM your address to me.

I wrapped the outside cauls with wax paper to minimize finish scratches.

I got ambitious and did two cauls at once on a crack that spanned a brace. Three down and one to go.

The 22.5 degree grain direction is as good as 90 degree cross grain in my view. T.J. says on his website that he choose this angle based on vintage tone bar angles.

One of the very interesting features of T.J.'s system is the way the cleat fits into a matching groove on the inside caul. This keeps things from shifting around during assembly. Your veneer cleats, or my double veneer cleats, could be set inside a rectangular groove in some kind of flexible caul. A...

Thompson's cleats are .056" thick so I think you might want to double up on your veneer strips to get an equivalent strength. I will have to do some tests with Thompson's cauls to see if I can get them to flex against guitar sides. Making an extra flexible caul is an interesting idea, Clay, because ...

One caution: the magnets are really strong. So the outside caul can scratch your finish when moving it due to the extreme down force. I think a patch of cloth under it would be a good precaution. Also, the cleats are really small and would be difficult to machine yourself. Buying them from ProLuthie...

Warm things up, smear some HHG on the crack and work it in, clean off the glue, tape the outside caul down, apply glue onto the cleat and place it in the guitar. This all takes about as long as it takes to read this list. This is so much quicker and easier than traditional back repair methods. I exp...

Trim the cleat flush to the ends of the caul.

Press the cleat into the goove.

More progress. I can't reach all the way to the bottom of the guitar so I made a handle and attached it to the back of the magnets with the ultra strong 3M double sided tape.

Then place double stick tape to the groove in the inner caul where the cleat fits.

The magnets are stuck to the cauls with double stick tape. As far as I know, you can only buy the cauls and magnets as a kit and it includes three sets of different lengths. The magnets are arranged so that they essentially act like one big magnet.

And then locate the outside caul. The inside caul is a little bit long and needs to be trimmed to fit between the braces, or in this case, the lowest brace and the kerfing.

I am happy with the results so will proceed with the actual repair. The first step is to map out the brace locations with a couple of magnets.

A bit of cleanup with a damp rag and it looks good. There are no visible gaps in the joint.

The cleats are 3/8" wide and .056" thick, with a rounded back profile. They are small compared to the normal diamond shape cleats but should be sufficient to reinforce the crack. The magnets put a lot of force on the joint giving a very solid joint. My test piece turned out fine. The HHG did not sti...

The real reason I am posting this repair is a new method for repairing back cracks that I am trying for the first time. T.J. Thompson sells crack repair tools that are very innovative. Stew Mac sells his kit for top cracks, but if you want his back crack kit you will have to look at his own website:...

The back binding had pulled away from the waist on both sides. I was able to loosen them up to the neck and reglue them. This will allow me to only have a small piece that I have to add at the top behind the neck heel cap.