Route Control cavity on contoured instrument without pin router

Discussion in 'Luthier's Corner' started by bigbadbuck, Jun 27, 2020.

  1. bigbadbuck


    Jun 28, 2005
    Southeast Iowa
    Say you have a contoured body like a Warwick thumb, how would you go about routing for controls without a pin router? Would you need to get out the gouges and a set of calipers?
  2. bholder

    bholder Affable Sociopath Gold Supporting Member Supporting Member

    Sep 2, 2001
    Vestal, NY
    Received a gift from Sire* (see sig)
    I've been meaning to ask the same question regarding neck and pickup pockets, for a few carved or arched top bodies. Subbed for learnin'.
  3. Gilmourisgod


    Jun 23, 2014
    Cape Cod MA
    I'd set up a template shimmed flat over the bass and route through that with a template bit with a top bearing. Is the back of the bass flat? If so, you know it will lay flat on a workbench. Just make a MDF template thats tight to the highest point of the top, and shim it level all around.
    Beej and bholder like this.
  4. Beej


    Feb 10, 2007
    Vancouver Island
    Double sided tape, shims and a handheld router. :thumbsup:
    bigbadbuck and bholder like this.
  5. Bruce Johnson

    Bruce Johnson Gold Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    This is where collar routing shines. Attach a steel collar to the router base. It's a steel sleeve that surrounds the router bit, extending down about 1/2". You can buy collar kits to fit most popular routers. Or you can build your own router base with a collar on it, a sleeve of aluminum tubing epoxied in.

    With collar routing, the opening in the template has to be cut larger in size all around, an "offset" to match the difference in size between the collar diameter and the bit diameter. For example, if you are using a 1/2" bit and a 1" collar, then you need an offset of 1/4". The opening in your template needs to be 1/4" larger all around.

    Fasten the template to the body with clamps, screws, or tape. Make it level, resting on the highest part of the body contour, and using blocks or shims under it where the contour slopes down. The template has to be secure.

    Now do the routing. The collar on the base rides around in the template; the bit never touches the template. Make the first pass with the bit only 1/8" deep into the highest area. Keep making passes, going 1/8" deeper each pass, until you reach the final depth that you want.