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4 string 36" scale Cocobolo-Ebony-Pau Ferro CT inspired

Discussion in 'Luthier's Corner' started by Matteo Marziali, Jan 12, 2013.

  1. I’m gonna share with you the building of a bass strongly inspired by “master” Carl Thompson.


    4 strings
    36” scale
    24 jumbo frets
    Set-neck construction
    Width at nut 42mm (1.653”)
    Thickness at nut 21mm (0.826”)
    Width at 12° fret 54mm (2.125”)
    Thickness at 12° fret 24.8mm (0.976”)
    Body thickness 28mm (1.102")

    Neck laminated Mahogany/Walnut/Mahogany whit Ebony binding and dyed veneer
    Makassar ebony fretboard without dot, 16” radius
    One piece Mahogany body 18mm (0.708")
    Cocobolo/Ebony top 5mm (0.196")
    Pau Ferro/Ebony back 5mm (0.196")
    Pau Ferro heel block
    Ebony headstock front and back
    Finish with Danish oil

    Passive electronics:
    2 Bartolini humbucker W4BCB with Cocobolo/Ebony cover
    Switch DPDT for PU selection
    Volume pot 250Kohm ( or 500K???)
    Tone pot 250Kohm with Mallory cap 0.033uf
    Switch DPDT for tone-bypass/tone pot/tone pot+treble defeat with an extra Mallory cap 0.022uf (or 0.033? Any suggestion?)

    Black Hipshot A style bridge 19mm spacing
    Black Hipshot Ultralite Y tuners

    This is an old render, something gonna be different:


    Pau Ferro
  2. Splods


    Oct 7, 2012
    Adelaide, SA
    Those woods have some beautiful grain on them. Best of luck.
  3. rick0link

    rick0link Supporting Member Commercial User

    May 22, 2010
    Washington, Pennsylvania USA
    Beardly Customs
    Subbed, oh hell yeah.... SUBBED!
  4. I have no photos of neck lamination, I made a sandwich with Mahogany / black veneer / red veneer / Walnut (5mm thick) again veneer and Mahogany.
    Then I cut the neck blank creating a "wedge" thinner towards the nut and thicker toward the heel, we can see in this photo:

    I routed the TR channel parallel to the back of the neck, so as to create a triangle of forces between TR and strings, thanks to the different inclination of the two planes of the neck:

    I cut out the scarf joint with an angle of about 12°,
    I cut a recess for TR nut,
    I applied the TR single action gluing the heel with epoxy and I closed the channel with a strip of wenge:

    P.S. sorry for my bad english :meh:
  5. Teacher


    May 3, 2012
    Your English is fine, and your design is quite beautiful!
  6. Do you give me an A, teacher? ;)
    Thanks for the appreciation!
  7. I keep on showing my building:

    I glued the fretboard (previously shaped) and clamped with spring clamps. I saw this technique on Pete Hilton's site. As you know he is the "chief luthier" at CT, but he also make some stunning bass at home (but without vacuum pump like the one he use at Thompson's shop :smug:)

    Headstock ready to be glued:

    Headstock glued and clamped!
  8. Splods


    Oct 7, 2012
    Adelaide, SA
    I remember that someone was having problems with their Cal Thompson esque bass because they couldn't find strings long enough for the 36 inch body through scale.

    Do you know what you will be stringing this up with?

    I was looking up double bass strings for a lark, and a short scale double bass is 36 inches, that doesn't include the length of the tailpiece to the bridge, so You could potentially string this up with double bass strings.

    I have a feeling that it wouldn't end well though, I wonder if anyone else knows?
  9. I'll anchor the strings on the bridge, not through the body, so i hope to have no problem with extra long scale strings...
  10. Some pictures of gluing the veneers and binding on the sides of the neck/fretboard. As shown in the second picture the veneers will be red for the back and green for the top, I made this choice because the Walnut and Pau Ferro have a cold tone that contrasts well with red veneer, while the Cocobolo is warm and looks good with a cold green veneer. IMHO of course!:smug:


    VVVVV (lot of chaos in my micro-workroom...:meh:) VVVVV

  11. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars
    That's a beautiful chunk of fretboard you have there
  12. Yes, a good piece of mac ebony!

    I keep on post some random pics.
    Of course some pic while i'm working could be more interesting... but i have only two hands!

    Gluing headstock wings:


    Dressing and polishing the frets:

    Maybe fretting and dressing before shaping the back of the neck could be strange for someone , but i was wondering if would work. I'll let you know!
  13. Updates about the back of the body::

    In order to have the electronics cover (on the back) with wood that matches perfectly with the rest of the body back I cut the cover with a fine scroll saw,
    and then I filled the space sawed by the blade with a veneer of 0.6mm

    Then I did the electronics "hole" on the body to align the cover, here's a placement test:

    And now how i glued the back: I glued the Pau Ferro sides, using the Ebony center as a support, then I glued the Ebony center pushing it with a hammer in his place. Being narrower at the top allowed me to let the joints adhere perfectly.
    But i put it too much inside and i bend slightly the body. :meh: But if i do the same with the top i should solve the problem...

    I'm realizing I work in reverse.
    I put the frets before shaping the neck, i did the electronics cover before the whole body... should I worry? :eyebrow:
  14. Grant Bass

    Grant Bass

    Oct 14, 2010
    I think you will do fine lol!
    really nice build, been watchin from the start
  15. Thomas Kievit

    Thomas Kievit Guest

    May 19, 2012
    Beautiful! :eek:
  16. Below some pictures of the process of gluing the top
    (i cut it as option 4 of Cocobolo top poll 2.0 )

    As you can glimpse from this photo I dug with the chisel the channels for the wires of the PU and the mass of the bridge
    (I hate to make the holes with a drill, i hate the drill bits that bend and break inside the body and i hate the spindle that ruins the top.
    I'm not able to do it! :spit:):

    After gluing the wings, I pushed the Ebony center to straighten the body:

    I clamped it well:

    The only flaw is gluing the green veneers, the left one is slightly raised up and there is a little space below,
    I think we will insert a veneer micro-wedge....

    Ah, a little explanation as to why I pasted the top and the back already cutted: to not throw anything away, of course!
    With the remnants of Pau Ferro I made the heel-block,
    while the remains of Cocobolo will be use as PU covers, TR cover and logo on the headstock.
  17. Detail of electronic cover, i routed it to have more space inside the cavity
  18. Here is the body ready to be carved. I placed the Hipshot bridge and the Neck just to see how it will look assembled

    Hipshot tuners:

    Full view:

    I lost a bit of enthusiasm in the construction of this bass, because my "customer" some month ago told me to work slowly because he has other expenses to deal with, and now he no longer responds to my messages...
    Perhaps doesn't he want this bass anymore?...
    This situation is a bit frustrating... Any advice? :meh:
  19. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    That's nice work on the cavity cover.

    Do you plan to leave a sharp step between the shaped top layer and the body core, or to do some rounding or blending?

    As far as the customer situation, it doesn't sound good. You might consider stopping work until you have an indication that you still have a customer. Either that, or put aside any deposit he has given you, so you're prepared to give it back when he asks for it back a few months from now, and you finish the bass to sell elsewhere.
  20. bigbadbuck


    Jun 28, 2005
    southwest iowa
    Hi. I may be having a brain fart here, but how did you get the scroll saw blade in to cut the cavity cover in the first place?

    I've always wondered how builders can cut a line so thin with a saw and not using a router.