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Headless four string ”Brucefied”

Discussion in 'Luthier's Corner' started by MPU, Feb 24, 2018.


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  1. MPU

    MPU

    Sep 21, 2004
    Valkeala Finland
    After taking a false step to headed, factory-made bass with horrible balance and heavy weight I’m taking a step back (or rather forward) to headless, own design and make bass. I’m planning to use and try the things I’ve read from Bruce’s posts as much as possible.
    -truss rod from Bruce with cf back strap
    -Brucebars for bolt on neck
    -brass or aluminium blocks epoxied to the body for mounting of the bridges
    -weakening of the body with chambers in the center area as well as weight reducing in other areas

    I’m going to make maple neck with Pao Ferro fretboard, 32” scale. Body is going to be plain alder with possible sunburst. Finish either Tru oil or something water based, I’ll have to find out what’s available here in Finland.
    Pickups will be my own sidewinders with adjustable pole pieces. Bridges are from ABM. I was going to make the bridges myself but at 39€ per unit for ABM there’s no sense in that IMO.

    Here’s the drawing, as you can see the body is going to be pretty small and hopefully lightweight.

    0783016D-6B03-4850-A786-B1A98B096C77.
     
  2. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Brucification is spreading to the European continent! Alert the authorities!

    Sounds cool. I think you'll like the results.
     
  3. MPU

    MPU

    Sep 21, 2004
    Valkeala Finland
    I’m pretty sure I’m going to like it. The truss rod itself made an audible difference to the bass I first used it.
     
    mobdirt likes this.
  4. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    I keep telling people that....But you know how it is around here. The majority of TB readers believe that structural details couldn't possibly have any effect on the sound of an electric bass. Because Leo. How could anyone dare to try to improve on Leo's design. Etc. I'm glad that you are helping to spread the word.
     
  5. MPU

    MPU

    Sep 21, 2004
    Valkeala Finland
    I’ve tried to listen with my ears, not with my eyes. I’ve also tried to feel how the bass feels and balances in my lap, not to look how it feels. Headless is so heretic already that I’m good soil for these improvements you’re doing on your basses. Thanks to you for telling us.
     
    Jisch likes this.
  6. rojo412

    rojo412 Walnut is fun! Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    Sub'd! Always love an MPU build.
    The fact that it's been Brucified only makes me more excited.
     
    tbrannon likes this.
  7. MPU

    MPU

    Sep 21, 2004
    Valkeala Finland
    8EB8A0D3-9D0A-4310-9A39-F4FC1EA4EFA2. 950A569E-9236-4D5D-8BD1-51AB005A15B7.

    Brucebars and plans for softening chambers made this morning.
     
  8. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Don't forget to put a small countersink on the threaded holes. That will make it much easier to get the screws engaged correctly when you are putting it together. Are you using M5 x 0.8?
     
    mobdirt likes this.
  9. MPU

    MPU

    Sep 21, 2004
    Valkeala Finland
    I have M4 threads on the bars at the moment.
     
  10. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    I use US 10-32 screws; the closest metric size is M5. But I'm sure the M4's are strong enough. I've used 8-32's for neck screws in a couple of special cases, and they were fine. With machine screws threading into brass blocks, we're not getting close to their tensile strength limits.
     
  11. HaMMerHeD

    HaMMerHeD

    May 20, 2005
    Norman, OK, USA
    So the brucebars are bedded into the neck? Acting basically as something like a "compound" threaded insert?
     
    mobdirt likes this.
  12. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Yep. They go into routed slots on the top side of the neck heel, before the fingerboard goes on. I've tried just about everything, and this is the best method I've found for attaching bolt-on necks to bodies. And yes, it does make a significant difference in the overall sound of the bass, improving the low end clarity.
     
    mobdirt and HaMMerHeD like this.
  13. Jisch

    Jisch Supporting Member

    I missed the other post where you described those in detail (I've tried to find it to no avail) how do you locate the holes in the body? I usually go the opposite order: drill the body, then use those holes to mark the neck where I put the inserts.
     
    mobdirt likes this.
  14. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    On that same subject, here are the Mini-BruceBars, which I use on some other clients' necks, particularly when the hole pattern isn't symmetrical.

    Same basic idea, just short blocks of 3/8" square brass. A single 10-32 hole tapped in the middle. Set into routed slots in the top of the neck. In this case, I don't bother to round off the ends of the blocks. I just cut the length so that they wedge down in against the rounded ends of the slots.

    IMG_4271B. IMG_4344B.
     
  15. HaMMerHeD

    HaMMerHeD

    May 20, 2005
    Norman, OK, USA
    Only brass? Have you ever tried anything like stainless steel or titanium, or carbon fiber?
     
  16. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    You can work it from either direction. On my own Scroll Basses, I just have templates and drill guides made up to make sure the holes line up to each other, all in relation to the centerline and the end of the heel/neck pocket.

    If I'm making up a new neck to fit an existing body which already has the holes, I'll make up a cardboard template that fits in the neck pocket. Transfer punch the hole locations through the holes, onto the cardboard template. Then put that template on the top surface of the heel of the neck (no fingerboard on yet) to transfer the locations.
     
    moonshinegtrs and mobdirt like this.
  17. Jisch

    Jisch Supporting Member

    Thanks.
     
    mobdirt likes this.
  18. Bruce Johnson

    Bruce Johnson Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Brass is the best material. Stainless machine screws threading into brass threaded blocks is the best combination out there. It's nearly impossible for those two metals to corrode together or gall or seize up. You can soak them in salt water, and they will still come apart.

    Stainless screws into stainless threads is asking for trouble. A small bit of dirt or friction heat, and they will lock up solid, permanently seized. Titanium is almost as bad. You can't really thread carbon fiber. Metal inserts are usually used to attach screws to carbon fiber parts.

    I do use aluminum for the BruceBars, in cases where we're really going for light weight. Not quite as durable as the brass, but they work okay.
     
  19. MPU

    MPU

    Sep 21, 2004
    Valkeala Finland
    C7419C7C-43E0-409E-B440-169ACF84F233. Body halves glued. Tomorrow I’m thickness sanding the halves and start routing the softening chambers.
     
    mobdirt likes this.
  20. MovinTarget

    MovinTarget

    Jan 30, 2018
    Maryland, USA
    I am currently doing a couple of Headless kits from Solo Music (from Canada)... One guitar, one Bass... Not heretical at all to me!

    I know I'm not at the "from the ground up" level yet but I love these threads!

    Looking forward to seeing how this turns out!
     
    mobdirt likes this.

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