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Sanding before epoxy, how fine to go?

Discussion in 'Luthier's Corner' started by ReidK, Jun 1, 2014.


  1. ReidK

    ReidK Jst sy n t lsy cmprsn. Supporting Member

    I'm gluing an Indian rosewood fingerboard to a maple neck with Smith's All Wood Glue (a fairly slow-curing epoxy). How smooth should the wood be? I sanded both pieces, of course, ending with 220-grit paper, but I'm wondering if the wood is now too slick and and should have more "tooth". Should I go over it with 120, or proceed with gluing?

    Thanks for any advice.

    Reid
     
  2. Igor Porto

    Igor Porto

    Mar 6, 2013
    I sand with 80 grit prior to gluing with Titebond.

    Since epoxy has better cohesion than adhesion, I think 220 is too smooth.

    But, why epoxy? Why not the good and trusty Titebond?
     
  3. ReidK

    ReidK Jst sy n t lsy cmprsn. Supporting Member

    I emailed Smith with this question. They replied very promptly (on a Sunday!) and said that 220 was OK, but the best bet would be some very light crosshatching with 120, so that's what I did. It's clamped and curing now. We'll see how it goes.

    After exhaustively researching this topic, I decided that if it's good enough for Rick Turner, it's good enough for me. :)

    Reid
     
    Igor Porto likes this.
  4. JustForSport

    JustForSport

    Nov 17, 2011
    Well, I don't have any experience with that brand epoxy, but with West System, Pettit, System 3, or any commercial epoxies I've used:
    Once the epoxy sets, laminating two well-prepared wood surfaces, it is a far stronger connection than either of the woods it connects.
    Heat nor solvents will not defeat that connection- wood removal is the only way.
    Sure hope the trussrod, etc is right- everything will be permanent.
    Best and good luck.
     
  5. ReidK

    ReidK Jst sy n t lsy cmprsn. Supporting Member

    Thanks for the good wishes, and I think the truss rod is right. :).

    In my limited experience, epoxies, especially those that are intended as adhesives rather than hard finishes, will soften with heat. They're certainly a lot harder to undo than aliphatics or especially hide glue (which is one step above Velcro in this regard!), but it's doable.

    Reid
     
  6. ReidK

    ReidK Jst sy n t lsy cmprsn. Supporting Member

    Update:

    The Good News: For the record, Smith's All-Wood Epoxy is surprisingly easy to undo with the application of heat. The old clothes-iron-with-aluminum foil technique got the fingerboard right off. I had to get it a bit hotter than I did in the past for aliphatic glues, but it didn't scorch the wood at all.

    The Bad News: I discovered the Good News after I broke my new truss rod. :facepalm: Probably my own fault, though it broke at a weld point and I was surprised at how little effort it took to break it.

    Reid
     
  7. JustForSport

    JustForSport

    Nov 17, 2011
    Good news that you were able to remove the fingerboard that way...
    I had a trussrod break at the weld (opposite end from the socket), and when I looked at it, saw that the original welding had left very little mat'l holding.
    So, I 'V' votched both sides of the weld area, leaving just enough to re-seat both pieces exactly as they originally were, and had it mig-welded. Then I ground it back down to flush.
    Lots more weld to hold now, and no more problems.
    By doing the 'V' notch and clean up work after, the welding itself cost me $5.
     
  8. ReidK

    ReidK Jst sy n t lsy cmprsn. Supporting Member

    Mine broke at the socket end, but the weld looked shallow to me, too. I know just enough about welding to get into trouble. :) I own a small MIG welder and I'm tempted to try to fix it, but for now I just bought another (which is out of character for me... maybe I'm getting old).

    Reid
     

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