
Oh yeah, looks like I left out a rather crucial detail Dave. Double backed tape, the fabric kind, I think it's called carpet tape over here, used under the edge of carpet to keep it in place. It's pretty powerful stuff, I also use it to hold cauls in place for gluing the bridge and fretboard overhang and have learned from experience to use the least possible to keep the caul in place as I've had a few times when I thought I wasn't going to be able to get the caul unstuck after being clamped overnight. It seemed to do a good job of holding the template in place for routing but I did a couple of test runs on some pine to make sure first.
Another thing I forgot to mention is how I made the template. I used Hann's method from his Spanish neck joint tute in the jigs and fixtures section, where the headstock is sawn apart on the bandsaw and then glued back together, avoids the wiggles and jiggles you get from trying to cut the slots on the scrollsaw or handheld jigsaw.
So this did make for a cleaner job, but it's still pretty nerve wracking routing those slots and hoping something doesn't shift or splinter. Definitely need to get a good spiral carbide bit before I do it again, and would probably be smart to cut the slots before doing all the neck shaping in case you blow a slot then at least you won't have wasted all that time carving.
Or hey, maybe get smarter yet and do paddle heads instead?
Naaa!
Joe