Interesting to see your "sub-size" approach to the carbon rod routs. I'd be a little concerned putting stress on the timber - I would never dare to do that for example with a wenge neck which is super stable in one direction but very "brittle" along the grain and could easily split. Doing a slightly oversized rout and glueing the rods in achieves a tension-free situation, and those rods will be not move provided they're fully surrounded by epoxy.
I also made templates to suit a template bit (with a ball bearing). To get a straight and 90 deg edge I used, wait for it, a template bit and the untouched edge of an MDF sheet. They are pretty much perfectly straight (but there's a little bit of "texture" which transfers to the piece you are making - can easily be sanded out at some stage), and I simply clamped it so the edge was EXACTLY on top of the line. Perfect. Bit of a mess (routing MDF is not a lot of fun) but 100% straight and 90 deg. Have used one template for my current build and am super-happy.
I'll probably end up with a number of those neck templates since the width at the heel not only depends on the number of strings but also on string spacing.
Looking forward to more progress pics.
1) I drilled guide holes into the template at the zero fret and at fret 22 (that's the last one for my current build). For me (considering the way I do the body-neck connection) perfect alignment is absolutely crucial, and this helps positioning the template. I'll post pics later today.
2) I don't change the size of the headstock between 4, 5 or 6 strings. The Kermit headstock was originally designed for a 6 string multi scale but works fine for a 5 string "normal" bass. Manta and Q are based on a somewhat oversized 4 string headstock which works just fine for the 5 stringers - at least for me.
- Merlin “Kermit” 6 multi, Merlin Gaia 6 fretless, Merlin Rockmachine 5, Merlin NT5, Manta 5, Manta 5 YOLO, ("Red Baron" 5), Q 5, (Sandberg Classic S2-5), (Thumb-4)
- Genzler Magellan 800, 2 Genzler BA12-3