A question of wood suitability

Discussion in 'Luthier's Corner' started by Hambone, Jan 13, 2005.

  1. I've been really jonesin' for a walnut neck on my latest build. I've got a big 4" x 4" piece of black walnut that is well dried (maybe 10+ years) but the problem is that it's the real core of the log. The 1" diameter heart is offset well to one corner but I'm wondering of the suitability of the rest of the board. I would cut about 2" off and then rip it into pieces to reglue into a quartersawn arrangement. The grain in the individual pieces, though essentially vertical, would have a noticeable arc to it.

    Is this too close to the center to be able to stack up a blank that will remain stable? Even with alternating the grain orientation?

    Thanx guys
  2. Suburban


    Jan 15, 2001
    lower mid Sweden
    With some clever placing of the ribs, it should be OK. By that, I mean that more narrow curved pieces should be more in the center, and contra-turned in respect of the grain curvature.

    Another trick, that comes to mind, is to cut the plank into two triangles, then cut away the heart corner of both and slice the rest. I haven't thought much about rib sizes, but it might work. The pro is, that you won't need to cut off 2", merely the very heartwood! And the rest may come in handy for something else, further on.
  3. Thanx Sub,

    I'm sure I've never used a piece of hardwood from so near the center of the log. I really didn't even know it before I started because the ends were cut in a way that totally hid the ring pattern. It was a surprise to trim it square and discover this.
  4. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    When working from a piece of stock that is farther from the center, if you rotate half the board pieces 180° about the long axis, any internal lengthwise bending forces (camber or sweep) will counteract each other. While this will be less so in a piece this close to the center (less symmetry), it is probably still beneficial to do so.

    Also sounds like this is a good candidate for some carbon fiber reinforcement, both because of the location of the boards in the log causing potential instability, and because walnut is a bit more flexible than the rock maple we are accustomed to.
  5. So your suggestion is to turn them end for end as well as orient the grain vertically - if I'm drifting the way you are?
  6. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    No, not end for end-- I thought this would be good too, until I did a "paper model" of boards with bend forces in them. What does work to make forces cancel, is to rotate half the board around its long axis by 180°.

    For example, take a board that is 1x6, rip it lengthwise into two 1x3s, flip one board upside down (assuming the two boards were laying flat on a table), and stack one board onto the other to make a 2x3. Another way is to take a e.g. 2x3, rip it along its thickness to make two 1x3s, then rotate one of them around its length axis by 180° so that what was once an exterior face is now an interior (glue) face, and glue them back together.

    I got the idea to check out the effct on stability from reading the Peavey patent for their Unity neck, which was then expanded upon by Fender to make the Music Man (or was it G&L?) Bi-Cut neck. Increased stability is not mentioned in the patents, they deal with the manufacturing advantages. Plus I think some other luthiers may routinely do this.
  7. We're saying the same thing. When I referred "alternating" the grain in my first post, I was referring to this method - alternating the arch of the rings to face each other and back each other to help cancel out their inherent stresses. In this case the grain will be oriented vertically or as best as I can with the tight arc that the grain presents.
  8. Wademeister63


    Aug 30, 2004
    Denton Tx
    Woohoo! Looks like I done good according to the discussion here.

    You mean like this eh?

  9. FBB Custom

    FBB Custom TalkBass Pro Commercial User

    Jan 26, 2002
    Owner: FBB Bass Works
    Hey Hambone - sorry I never got back to your PM until today. I've been swamped.

    The issue with the pith goes beyond cupping and warping. The pith is often weak for other reasons. Wood can separate at the pith and trees get weak as they age from the inside-out. How far from the pith you should work with can vary depending on the particular species.

    I would think you could get a sense of where the wood gets bad by reading the end grain. Take a look at how tight the radius of the growth rings are where you would like to use it and compare it against other specimens you have used; you may be surprised to find that you have worked with wood fairly close to the pith before, especially if you have used some of the smaller-growing trees like some of the rosewoods (tlip and king wood).

    I think you're probably all right from your description. It would be ideal if you could blast some pictures up. Of the end grains especially. Another consideration is that the pith may wander a little bit and so watch out for that.

  10. I had a nice response in email from a very reputable source that pointed out that the juvenile wood about 1" out from the pith isn't usable either. He also described the method of marking out the pith for cutting. That leaves me just enough to reface the sides of an old Pioneer receiver and start a nice fire. WooHoo!

    All of you guys have been most helpful. Matt, good idea going back to look at what I've used in the past. Instant archive!
  11. FBB Custom

    FBB Custom TalkBass Pro Commercial User

    Jan 26, 2002
    Owner: FBB Bass Works
    I would think that you could use some of the pithy wood as long as it wasn't load-bearing and if it was too pithy you took steps to stabilize the wood. Like some of the CPES that Rot Doctor and West Systems sells.

    If you wanted to, that is. I hate burning anything but oak, ash, and small maple.