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Plastic bridge and neck plate?

Discussion in 'Luthier's Corner' started by BassUrges, May 31, 2020.


  1. BassUrges

    BassUrges

    Mar 14, 2016
    Denver
    Has anyone ever made a bridge or neck plate out of acrylic or polycarbonate? I have in mind a Tune-O-Matic style bridge from acrylic and a neck plate in 1/4” polycarbonate. I can do destructive tests to assess feasibility, but if anyone had tried it that might save time.
     
  2. Jazz Ad

    Jazz Ad Mi la ré sol

    Polymers as a whole resist badly to shearing. Acrylic and polycarbonate resist worse than the average polymer.
    i think it makes them a poor choice for a bridge or neck plate. The base of the bridge could do fine if you use quite flat and large saddles.
     
    Rabidhamster likes this.
  3. Will_White

    Will_White

    Jul 1, 2011
    Salem, OR
    1/4" would probably be strong enough for the neck plate, are you wanting just the saddles out of poly for the bridge? What are you trying to achieve?
     
  4. BassUrges

    BassUrges

    Mar 14, 2016
    Denver
    Ideally the base and saddles would be clear plastic (and clear polycarbonate intonation screws). Action would have to adjusted by filing so the saddles could just sit flat.

    The goal is minimum visibility.
     
    Old Blastard likes this.
  5. BassUrges

    BassUrges

    Mar 14, 2016
    Denver
    A secondary goal is, I’m completely nuts.
     
  6. Will_White

    Will_White

    Jul 1, 2011
    Salem, OR
    I'd use just floating saddles then no screws or plate for the bridge and go string through.
     
    pellomoco14 likes this.
  7. BassUrges

    BassUrges

    Mar 14, 2016
    Denver
    Yes, a floating bridge like Gibson uses. I don’t expect this to hold string tension. I’ll be putting headless tuners behind it.
     
  8. Jazz Ad

    Jazz Ad Mi la ré sol

    Shergold basses used acrylic as part of their bridge.

    TE.jpg
     
    JIO and mikewalker like this.
  9. Dirk Diggler

    Dirk Diggler Supporting Member

    Mar 3, 2004
    Anytown USA
    If it doesn't have to be clear, corian is a very strong material. I don't think the clear stuff I've seen will be strong enough, notice how thick that bridge on the Shergold is. Cool bass by the way Jazz Ad!

    Neck plate would have to be a big inlay in order to hold up, once you start drilling holes in lucite/acrylic it gets very questionable in thin parts. Certainly couldn't make it thin enough to surface mount.

    Good luck,
    Dirk
     
  10. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    As you probably know, I have a long history of building custom bass hardware from all kinds of materials. But I've never made one from acrylic or other plastics. I think you could do it, but it'll be tricky. The main problem will be preventing cracking around screws. You have to make sure that none of the screw heads or threads are pushing out radial forces.

    For example on the neck plate, you couldn't use countersunk neck screws. The outward force of the screw head in a countersunk hole would easily split the plastic. You could use a big Truss Head screw head, or a washer or ferrule under the screw head. Something so that the force is just pushing down flat on the plastic, not trying to spread it apart.

    If you want clear plastic, then you have to use Acrylic (Plexiglas) or Lexan. Lexan is stronger and more crack-resistant, but not quite as clear. Dirk is right that Corian is a good tough plastic that machines about like aluminum. But it's opaque white. Delrin is another option, a strong machinable plastic, but it's only available in opaque white and black.

    If you are really set on making the parts from clear acrylic, you might consider casting them, rather than machining them. Same process that we use for making bobbins over on the pickup building thread. Make up a Master from metal, wood, or plastic. Make a silicone rubber mold from the master, then cast the part with clear acrylic resin. That would save you a lot of time machining and polishing the acrylic. And, if you break one of the parts during finishing operations, you can quickly cast another one.
     
    JIO, Beej and Will_White like this.
  11. Will_White

    Will_White

    Jul 1, 2011
    Salem, OR
    Why do you want the neck plate to be clear? Would neck ferrules not work?
     
  12. bassdude51

    bassdude51 "You never even called me by my name." Supporting Member

    Nov 1, 2008
    Central Ohio
    Carbon fiber would work, I'd think.

    Gotoh offers this carbon fiber bridge. Probably knocks off a several oz. So would a carbon fiber neck plate. WOW! This stuff is already out there. GO FOR IT!!!!!!!

    s-l400.jpg s-l400.jpg
     
    dusterdan70 and Jazz Ad like this.
  13. Beej

    Beej

    Feb 10, 2007
    Victoria, BC
    I think the goal is transparency, because the artistic gestalt of the overall image would benefit from the least visual disruption - at least how I take @BassUrges descriptions.

    I agree that casting it, perhaps in a slightly oversized version to increase strength, might work?
     
  14. BassUrges

    BassUrges

    Mar 14, 2016
    Denver
    Ive never seen acrylic casting resin. I’ve used epoxy, Polyurethane, polyester and whatever alumalite is. It doesn’t save much machining if all goes well, but it does make replacement easier.
     
  15. BassUrges

    BassUrges

    Mar 14, 2016
    Denver
    I was about to order some ABM headless tuners and my wife started flapping her arms and saying “You’re covering up the best part!!”
     
    dwizum, delta7fred and mikewalker like this.
  16. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Actually, I guess I was thinking of Smooth-On's Crystal Clear series resins, which are a rigid urethane resin.

    https://www.smooth-on.com/product-line/crystal-clear/
     
  17. mikewalker

    mikewalker Supporting Member

    Jul 30, 2017
    Canada, Eh!
    :) arm-flapping is a pretty effective cue...
     
    spvmhc and Old Blastard like this.
  18. Jazz Ad

    Jazz Ad Mi la ré sol

    I'd try to get rid of as many parts as possible and only keeping solid parts, rather than using acrylic.
    You could use a minimalist bridge and embedded ferules rather than a tailpiece.
    4 screws with spacers work just as well as a plate for the neck.

    4.jpg

    jzrjextjwvjpfbhthhfr.jpg
     
    Last edited: May 31, 2020
    RSBBass, pellomoco14 and TAZ like this.
  19. BassikLee

    BassikLee Supporting Member Commercial User

    Feb 13, 2004
    Deltona, FL
    Owner: Brevard Sound Systems
    The resin used to make custom in ear monitors is acrylic, UV cure. It's also pretty expensive. $200 for 500ml
     
  20. J_Bass

    J_Bass

    Feb 7, 2008
    Porto, Portugal
    For minimum visibility, it's better if the part is painted to go along with the background, than to be transparent.

    Assuming the parts are for the body in your avatar, you should just paint the metal parts to match with the painting of the body. Transparent doesn't work so well, it will be more visible.
     
    tzohn likes this.

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