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Lefty bass with laser cut templates & sliding dovetail set neck

Discussion in 'Luthier's Corner' started by james condino, Jul 30, 2017.


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  1. james condino

    james condino Spruce dork Supporting Member

    Sep 30, 2007
    asheville, nc
    I spend most of my time over on the double bass side but thought I'd show off this one. Here are a few shots of the sliding dovetail set neck that I'm working on with one of my students, Dustin. It is a lefty electric bass in cocobolo and Honduras mahogany. I've made hundreds of traditional configuration dovetails for dreadnought guitars and such but this orientation was a first for me. I had the templates made up in 1mm intervals on a laser cnc and then cut it with a router. A tiny spec of mahogany photobombed the dovetail....

    j.

    @kaybassrepair
    @condinostringinstruments

    or the ancient version:
    www.kaybassrepair.com
    www.condino.com

    DSCN3552.JPG DSCN3555.JPG
     
    Geoff St. Germaine likes this.
  2. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Nice work! Are you using a slight taper in width along the length of the pocket, or is it straight sided? What angle is that router bit? About 10 degrees?
     
  3. james condino

    james condino Spruce dork Supporting Member

    Sep 30, 2007
    asheville, nc
    Yes, it is a tapered dovetail with the width increasing from the top to the back of the body. I'd have to check the degree; it is the same one I use for all of my traditional guitar work- a big 1" with bearing that Whiteside makes here in North Carolina. That little bit of taper gives me a whole lot more confidence in the joint rather than just a simple mortise and tenon. I know either way there is plenty of surface area for adhesion, and hot hide glue will make it bombproof, but when you can pick it up dry fit and the joint holds the whole body in place it puts a big smile on your face.
     
    rwkeating likes this.
  4. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Oh yeah, the dovetailed side walls are obvious. I was asking whether it also tapers slightly in width from the front of the pocket to the back of the pocket. Or are the sides parallel?
     
  5. james condino

    james condino Spruce dork Supporting Member

    Sep 30, 2007
    asheville, nc
    The first one I made up did exactly that. It sounds great on paper until you realize that you cannot slide it in that direction! Tapering it in line with the fingerboard, a common practice with 90 degree sides in the joint, would create a kick a$$ joint, but fitting is impossible when you add the extra horizontal dovetail. You could make it work if it was wider on the exit side, but not wider on the inside. We prioritized a potential heel failure and locked it out with the dovetail feature vs the neck pulling out in the direction of the headstock. The whole thing is still a work in progress but so far it is working better than expected and everyone who has seen it says it inspires tremendous confidence. It may be a bit overkill. I regularly see straight mortise and tenon hot hide glue joints hold up for 200+ years on old upright basses, but they don't usually get used in a stage diving punk band by a 6'3" close to 300 lb person like this one will!
     
    Dadagoboi likes this.
  6. Geoff St. Germaine

    Geoff St. Germaine Commercial User

    Classy joint, I like it. I've used the perpendicular (to this) one on archtop guitars I've built. It's certainly a nice joint.

    I've seen Fodera uses something similar to this on their necks. I presume they must also use the angled wall, though I'm not sure that I've seen an image of it to say for sure.

    Look forward to seeing more! Cocobolo is one of my favourites and that looks like a great piece!
     
  7. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Well yeah, if it were tapered in width, it would have to be wider at the outboard end. Obviously. That's what I was wondering; if you had done that to make it easier to slip together with tight clearance.

    I machine up set-necks for several of my clients, but we've been making them simple, straight, rectangular. Pretty deep, but vertical parallel sides. No problems with assembly or failures so far, but they have to be machined and fitted precisely. I cut the heels in a milling machine, based on actual measurements from the routed pocket. We've been putting them together with 0.005" clearance for glue.