Neck/body carve on neckthroughs - concave or convex?

Discussion in 'Luthier's Corner' started by dwizum, Jun 7, 2019.

  1. dwizum


    Dec 21, 2018
    I've noticed lately that there seems to be (at least?) two approaches to neck heel carving on neckthrough basses. With a bolt on bass you're pretty much locked in to having a distinct heel, but on a neckthrough there's more freedom. Some people seem to carve a distinct convex heel, similar to a bolt-on bass, where the body material "bumps" out along the neck. Other people seem to carve a concave shape, where the body is scooped out around the neck joint.

    Are all you builders making that distinction based on access to upper frets? Or visual appearance? Or, are you like me, and you've just always carved a shape that looks good without actually thinking about it?

    I feel like the distinction is - if you drew a line that completed the body outline across the neck joint, does the body material extend above that line? Or is it scooped out below the line?

    I borrowed an example of a convex carve from @Jisch


    I couldn't find a great example of a concave carve in the 30 seconds I spent looking, so I'll use this not-that-great photo of the slightly concave carve on my 6 string:

  2. The first thing I do is draw a parabolic type line from the bass to the treble side of the neck. I carve out below it until it feels right. Usually it feels right, I let it sit overnight, decide that I didn't take enough off and take more off (repeat 2 or 3 times). I want comfortable access to the 24th fret all across the fingerboard. That doesn't necessarily mean it has to be scooped to the 24th, it just means it has to be comfortable. I hadn't really thought of this before but perhaps someone with shorter fingers than mine would want it more scooped out than I leave it. Also I want the neck to get thicker before the end of the truss rod, which is usually around the 18th fret.

    Incidentally on the actual carving, it's a lot of material to remove, I've tried a lot of different tools. My go-to now is an angle grinder. I draw the contour on each side of the neck and watch carefully to make sure I'm not going too deep. It's also important to watch the outside edge of the wheel, I have inadvertently hit the horn because I was so focused on the heel. It can make a mess in a hurry. The angle grinder leaves a pretty rough surface, I use a gouge and scrapers to clean it up.

    One other problem area for me is always getting the transition to the flat part of the neck right. It's impossible to get that transition smooth unless you take a little off the back of the neck on the flat part. I have necks where I have cut them to the absolute minimum thickness prior to carving - that's a bad idea because you can't make that transition smooth.

    I have a Carvin/Kiesel through neck here and I often use it as a reference when I'm starting to carve a neck heel. The carve on the back is more extreme than anything I do, I guess they trust their neck wood more than I do, or use longer truss rods. I know they embed carbon rods, so maybe they go further down the neck.
    dwizum and washjayb like this.
  3. Arie X

    Arie X

    Oct 19, 2015
    i like what jackson does:

    unless you have a cnc mill at the ready and can just surface it with a ballnose tool, it's fairly easy to do with a dragon rasp and either shaped sanding widgets or scrapers to dial it in.
    Beej and Matt Liebenau like this.
  4. dwizum


    Dec 21, 2018
    See, when it comes to comfort and ease of access up the fretboard, I was wondering if the opposite might be true. Your necks seem to have more of a pronounced heel than the 6 of mine I posted above, which I scooped way out in the hopes of improving access. However, when I'm playing it, sometimes I have trouble reaching all the way up and around the wide fretboard up in the highest frets - I wonder, if it had a substantial heel, maybe that would give me a place to kind of plant my thumb and rotate my wrist to improve reach?

    My fretless semi hollow 4 string does have a bit of a pronounced heel but the neck is so small on it, it's easy to reach everything no matter what.

    I'd love to hear from more people about why they carve them the way they do (looks? strength? comfort?)
  5. Slidlow

    Slidlow The Human CNC Supporting Member

    Apr 15, 2009
    Oshawa, Canada
    Here's the back of my four string fretless neck through built 32 years ago. Still stable and straight. Carve away! IMG_5492.JPG
    Beej likes this.
  6. Rôckhewer

    Rôckhewer Commercial User

    Feb 28, 2015
    Phoenix, Arizona
    Owner/Builder- RockHewer Custom Guitars LLC
    I used to carve neckthrough heel like this...
    (But only because Alembic does) 20170420_183847.jpg

    But now I do something that feels way better, full access to the 24th...
    Same basic horn configuration, but the lines are better now as well ... I feel.
    A "stiff" neckthrough needs no "heel" per se....
    One concern is the last few inches of the neck, outside the influence of the truss rod.
    If you're neck material is fairly flexible... you might need more support at the heel area.
    But, all my necks are 5 to 9 pc. laminated, I don't worry about it. ;)
  7. Rôckhewer

    Rôckhewer Commercial User

    Feb 28, 2015
    Phoenix, Arizona
    Owner/Builder- RockHewer Custom Guitars LLC
    Then again.... it depends on the situation (IMO).
    On this one, I couldn't bring myself to carve it out any more...
    Party because of aesthetic rationale.
    And partly because this bass will be subjected to "alternate" tunings AND overseas travel...
    So I wanted it to be as stable as possible.
    ...although my paranoia is probably unfounded.
    It really didn't matter here anyway, because the lower cut was super deep.
    Last edited: Jun 18, 2019