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Pick up pockets

Discussion in 'Luthier's Corner' started by Ericspaw, Dec 21, 2012.

  1. Ericspaw

    Ericspaw

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    I have wrapped up my first instrument build, a bass from mostly curly sassafrass. The pockets for the pickups are too tight after adding the shielding tape.

    How much slop can I allow around the pickups for adjustment before it looks too sloppy.

    Thanks

    Eric
  2. hover

    hover

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    1/32 to a weak 1/16 tops.
  3. Smilodon

    Smilodon Supporting Member

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    Keep in mind that some pickups are slightly wider at the bottom, so the gap will look a bit larger.

    On my last project I have about 0,3mm (1/64") clearance total (0,15mm on each side) at the bottom, but the visible gap is about 1mm.

    If the pickups are just slightly too big you could sand the bottom edge of it a bit. Just don't sand so far up that the sanded part is visible.
  4. Musiclogic

    Musiclogic

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    Owner/Builder: HJC Customs USA, The Cool Lute, C G O
    I like just under 1/16" with wood covers as after lacquer, it works out to about 1/32" and is just enough for wood expansion during the summer.
  5. tjclem

    tjclem

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    Owner and builder Clementbass
    You shield the pup cavities?
  6. Grant Bass

    Grant Bass

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    you don't?
  7. tjclem

    tjclem

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    Owner and builder Clementbass
    Never needed to. Leo didn't :bassist: :D
  8. Dadagoboi

    Dadagoboi Supporting Member

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    Disclosures:
    Cataldo Basses:Designer/Builder ThunderBucker Pickups:Consultant
    But he did use a full aluminum shield under the pickguard of the 2nd generation Precision (after the aluminum guards) and brass plates in the bottom of the pup routes and control cavities of both those Precisions and first gen Jazz into the 70s.

    OTH early Thunderbirdmpickups are self shielding due to their metal covers and bottoms. Many modern soapbars (definitely Seymour Duncans) are self shielded internally and don't need additional shielding.
  9. HaMMerHeD

    HaMMerHeD

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    Conductive paint is better.
  10. joeyl

    joeyl Supporting Member

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    I use conductive paint also, and it is black which makes the pickup cavities blend with the black pickup covers
  11. tjclem

    tjclem

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    Never tried conductive paint. What type and where are you all getting it?
  12. Beauchene Implements

    Beauchene Implements

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    I recently switched from foil to paint. I bought the small can from StewMac, I've used it on the electronics and pickup cavities for three guitar builds and my old Squire Jazz bass; three layers each, and I've barely used a quarter can. Never going back to foil. Great stuff.
  13. joeyl

    joeyl Supporting Member

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    I bought a few small cans on ebay. it is usually slightly cheaper than the stewmac stuff.
  14. HaMMerHeD

    HaMMerHeD

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    It's fairly expensive no matter where you get it. Stewmac is a few dollars more per 1/2 pint can than other places, but I'd rather pay that bit extra than play the ebay game.

    It's conductivity is provided by the graphite that is mixed in with the solvent. Basically, you paint it on and the solvent evaporates, leaving the painted surface covered with graphite.

    It's a nasty mess though, so a lot of masking is recommended.

    I also used it to ground the strings of a fretless bass with an ebony bridge. I sanded the black paint off the ends of the ferrules and painted the ferrule holes with the conductive paint. Then I painted a thin strip of the stuff all the way back to the electronics cavity, on the outside of the bass.

    When time came for finishing, I sanded the edges of the graphite paint so that it was a smooth gradient. Then I tested to make sure it was still conductive and sprayed a polyurethane sealer coat over it. Then I sprayed a few black satin paint coats over the whole thing, and then a few satin clear coats. I thought it was rather clever.
  15. Bruce Johnson

    Bruce Johnson

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    The best shielding paint I've found is SuperShield by MG Chemicals. It's available from various electronics suppliers. It's about $40 per spray can, but one can will do 10-20 instruments.

    The difference is that SuperShield uses powdered nickel instead of powdered carbon (graphite), as used in the Stew-Mac shielding paint. The nickel is lower conductivity and more reliable. I spray the cavities of all of my basses with two coats, and they read less than one ohm from any point to any point. The nickel is floating in a clear polyurethane base. It sticks very well, dries hard, and there's no powder or mess.

    I used the Stew-Mac for a few years, and I gave up on it because it was such a mess. To get decent conductivity and shielding, you have to paint it on thick, and a lot of the carbon powder ends up falling loose from vibration and age. Conductive carbon powder bouncing around in a chamber full of electronics components is not a good thing.

    Spraying the Super Shield is also a lot faster than brushing. They also sell small bottles of SuperShield with a brush in the lid for touchups. I bought one, but I've hardly used it. Two spray coats, drying about 20 minutes each, does the job. The shielding ends up a silver-gray color.
  16. tjclem

    tjclem

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    This sounds interesting. What if the body has been finished with an oil like Watco. Will the spray stick to it?
  17. Bruce Johnson

    Bruce Johnson

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    The SuperShield will probably stick to an oil finish if it's fully cured and there isn't slimy residue on the surface. If unsure, wipe the cavity with alcohol, or lightly scrub it with Scotchbrite.

    The base paint of the SuperShield is about like any of the usual spray can polyurethanes, like MinWax Polyurethane. It just has the fine nickel particles floating in it. It dries quickly and hardens completely. When dry, if you rub it you won't get any nickel on your finger. .

    On my new basses, I spray the base/sealer coats on the body first, including down in the control cavities. This is to make sure all the wood is sealed up moisture-tight. Then I spray the SuperShield in the control cavities. Then I mask off the cavities and do all the color coats and clear coats on the outside of the body.

    Attached is a picture of one of my AMB-2 bodies just after spraying the SuperShield in the control/pickup cavity. The masking is done with a plywood masking template temporarily pinned to the body. I spray 2 coats of the SuperShield 20 minutes apart and let them dry overnight. Fast and neat. The shield quality, in terms of resistance, thickness, and coverage is about equal to copper tape, and much better than the carbon-based shielding paint.

    Attached Files:

  18. tjclem

    tjclem

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    cool thanks
  19. joeyl

    joeyl Supporting Member

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    true the graphite paint makes a mess, I have started applying it in the cavities before spraying the final clear coat, and like that, it is covered with clear lacquer.
  20. Grant Bass

    Grant Bass

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    why not spray immediatly after doing the routes? then any mess will be sanded off during normal prep sanding/shaping ; this IS a question because i have never worked with it, i may be missing somthing, like.. you cant apply to bare wood or somthing?
    any products here in canada? alot of stuff like this we cant get; im going to check my electronics store after christmas for somthing like this!!!

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