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Fitting purfling strips as fretlines

Discussion in 'Luthier's Corner' started by Basschair, May 17, 2005.


  1. Basschair

    Basschair .............. Staff Member Supporting Member

    Feb 5, 2004
    Stockton, Ca
    I've found and read the few threads on making fretlines for a fretless bass, and went with a Warmoth preslotted fingerboard and StewMac purfling strips. The strips are an absolute perfect fit in the slots as far as thickness goes, but (of course) I've got a few questions.

    The purfling strips are straight and the fingerboard has a 10" radius. I clipped the strips with about an extra 1/2" on each end, which allows pressure to be applied at either end, and this bends them just right so that they accomodate the radius. But I don't have the time to glue one piece a day into the fingerboard and sit there for a few hours holding the strip in place. I'm thinking about using a rediusing board, lining it with (my new best friend) wax paper, and gluing maybe 8 strips at a time, laying the radiusing board on top with the paper in between, and then applying light clamp pressure which should hopefully press the purfling strips down into place (conforming to the radius). Think this is a workable approach?

    Second, I've been thinking so much about gluing super-strong joints and such that I've been very focused on using Original Titebond for my gluing needs. Should I back up and use a different glue for the purfling strips? And once glued, I was going to run some fine grit sandpaper lengthwise on the fingerboard (using the radiusing block) to slowly take off the tiny smidge of excess purfling sticking out of the slots. Would this also sand off any errant Titebond smears before taking off too much ebony?

    Any comments and life lessons are appreciated. Thanks!
     
  2. fretlessrock

    fretlessrock Supporting Member

    Aug 8, 2002
    Corrupticut
    Why are you bending the strips? If you need to radius the bottoms because the fret slot bottoms are radiused (are they?) then do that instead of bending them. Then you just level trim the tops off the strips with a plane as step one in re-radiusing the board.

    I'd use cyanoacrylate over titebond every time for a fretline job.

    You can and will be re-profiling the fingerboard anyhow but keeping squeeze-out to a miniumum will make the job go easier.

    The big no-no is to have the strips fit the slots tightly making the neck back-bow. This is the biggest pitfall with a defret.

    Hope that helps.
    Pete
     
  3. nateo

    nateo Schubie Fan #1

    Mar 2, 2003
    Ottawa, Ontario
    It seems to me it'd be easier to shave off the excess purfing than try and radius them as you glue them in. Personally I'd just glue them in so there's a bit sticking out along the entire width of the fretboard and sand the whole thing to radius. If there's too much sticking out, I think a razor blade would trim them nicely.

    Of course, I haven't tried this personally, so my post-modern inclination is to not trust what I just said. On the other hand, this seems to be a farily common procedure (a quick Google search turns up one or two tutorials).

    I was once told that you'd want to use epoxy for this procedure, since it doesn't cause the wood to swell. The idea there was that you'd use maple shims (or some other contrasting wood) to fill the slots and you wouldn't want them to swell after spending 20 minutes finding the perfect fitting piece.

    Let us know how it goes, and don't skimp on the pictures.

    -Nate
     
  4. tjclem

    tjclem Supporting Member Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    use CA glue. I did it worked well for me.t
     
  5. Basschair

    Basschair .............. Staff Member Supporting Member

    Feb 5, 2004
    Stockton, Ca
    Thanks for the advice, guys...

    I do believe that the slots are radiused, and when I apply a bit of pressure to either end of the purfling, it lays down and conforms to the radius. It did seem a bit odd, in retrospect. It sounds like my options are to either trim the strips a bit to match the depth of the slots, to try to cut the strips to match the radius of the bottoms of the slots, or perhaps use a thin coping saw blade to flatten out the bottoms of the slots without widening the slots at all so that the strips will be able to be inserted and have an even bottom of the slot to sit in.

    As an aside, it's a bit odd that the Warmoth site says the fingerboard is 2" at the nut, yet mine is 1 3/4". Not to complain: that's exactly what I wanted at the nut, though I will have to retaper, as the width at fret 24 is too much...
     
  6. tjclem

    tjclem Supporting Member Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    As I recall the stew mac fb's are raduised slots too.t
     
  7. I'm wondering what your opinions are on the pros/cons of flat/radiused fretslots for fretted/fretless basses.

    My inclination is that flat fretslots are less desirable for fretted instruments as there is a gap under every fret. Opinions?
     
  8. Basschair

    Basschair .............. Staff Member Supporting Member

    Feb 5, 2004
    Stockton, Ca
    The answer to that may be in the fact that my FB came with radiused slots, and apparently StewMac's do as well. That, of course, is an assumption...one of those evil correlation=causation things.

    The more I think about this, the more it makes sense to just knock down the slot radii a bit so that the purfling will be able to lie as close to flat as possible when inserted. At least, it makes sense in my novice world. :D
     
  9. gyancey

    gyancey

    Mar 25, 2002
    Austin, TX
    You don't want to force your fret line veneer to conform to the radiused bottom of the fret slots. ITs best not to glue in stress. Precut all your lines to approx length, put some 80 grit sandpaper on the fingerboard near its widest point and sand the radius into the bottom of each piece. It shouldn't take all that long. I would install each piece and flood either side of the raised part with super thin CA glue. The veneer is thin enough that it will probably soak all the way through and toughen up the lines while gluing them in at the same time.
     
  10. Basschair

    Basschair .............. Staff Member Supporting Member

    Feb 5, 2004
    Stockton, Ca
    Here's the new problem:

    Once I cut down the purfling to fit the radiused slot, I end up with strips that are a bit too short, so that they don't fill the slot entirely (not tall enough, leaving a gap between the top of the strip and the "lip" of the fretslot). I could fill the difference with CA and sand it flush with the fingerboard, or I could use a second tiny piece of purfling layed across the top of the first...thoughts?
     
  11. fretlessrock

    fretlessrock Supporting Member

    Aug 8, 2002
    Corrupticut
    This is why keping the filler strips tall and trimming/sanding them flush with the board is the way to go. I'd use a radiused block and level the board to the strip tops now that you have the shorty strips in there. I think you are asking for trouble by putting thin strips on top of the current strips.
     
  12. Basschair

    Basschair .............. Staff Member Supporting Member

    Feb 5, 2004
    Stockton, Ca
    Nope, haven't actually glued yet, so I'm still at the "open for suggestions" stage. I've been experimenting with shaping the strips and then laying them in the slots to see what will work, but have stayed away from glue until I'm ready to commit to one method.
     
  13. There are a few ways you can do it, more and better ways than I mention below. BTW, I use epoxy to glue veneer into the fretslots.

    Don't fill the difference, as it doesn't look nice. What I do is make the veneer strips high and wide, so that they stick out of the fret slot say 3mm after the bottom is radiused. This way, I have some give.

    Alternatively, I haven't tried this and haven't heard of anyone who has (not saying no one has), is to flatten the radius in the fingerboard. Care must be taken here to only flatten the middle of the fret slot till it is level with the sides and stop. The radius can be flattened with a dove tail saw or whatever you generally use to cut your frets slots.

    Another way, which I used in my last project, was the result of not getting a good fit with the veneer no matter how I tried to radius the veneer. So I tilted the veneer toward the right side of the neck (I'm right handed, so the right side faces up), and cut a wedge piece to glue in at the other end which faces down. The gap in the bottom side was not higher than the fingerboard. This leaves a thin kind of join line, but no one can really see it anyway so that worked ok for me.

    I don't recommend any of the methods I've stated, but it's just something to think about. Only saying that there are many ways to workaround the problem. It would be good if there was something to put in the fret slot that would mark the shape of the radius, sort like how a locksmith gets the shape of a key from a keyhole when there is no key.

    It's good that you're testing prior to gluing. That has saved you a headache or two.