Thought I'd share how I joined the neck to the box.

I bought a pre-made neck and fingerboard on ebay. For less than $20 shipped it was a no-brainer.

The neck terminated in a flat surface. I knew that plain old surface-to-surface wouldn't hold.

I measured a bunch then drilled a 1/2 hole in the neck, box and a bracing block that went inside the box.

I glued all of that together and it seemed to work but the joint failed after stringing it up. There is A LOT of tension in those strings. The neck peeled away from the body from the bottom of the joint. Luckily there was no damage!

I realized that a real fiddle's back is ALSO glued to the neck - for a total of 2 points of hold.

I cleaned up the old glue and used wood weld epoxy for a stronger bond.

And since my box is thicker than a fiddle I added an angle bracket to get the hold needed on the bottom of the neck joint.

Now the joint is strong and holding.