Alcoa Upright Double Bass Repair

Discussion in 'Setup & Repair [DB]' started by mylo, Mar 6, 2020.

  1. mylo


    Mar 1, 2020
    Hello, I'm a new member to this forum and I recently got a hold of an Alcoa Upright Double Bass and it was in very bad shape. Of course the neck was bent and one of the bosses was ripped out of the neck. I had someone help weld the bosses back on and it was a bad job but it worked.

    As I was researching how too straighten the neck, I stumbled on a few forums talking about how the same problem will happen again and again because of the poor neck design. So my question is has anyone gotten a solid and easy fix with pictures or videos on how to do this repair and strengthen the half round to the neck?

    I was thinking of using the same half round and using a forstner hole cut into the core and a countersunk spacer on the half round into the neck. Then glue the finger board on. My last resort would be to drill into the fingerboard but will this affect the sound if I didn't plug it?

    Also where would i even get a half round replacement?
  2. eh_train

    eh_train Supporting Member Commercial User

    Jan 12, 2004
    Owner, Stand Up Guy Basses (Repair/Sell/Buy upright basses)

    I have one that needs the neck repaired, though it’s not in too bad condition. My plan is to insert two carbon fibre rods into the half round (running the length of the wood, one on either side of the bosses). I’m thinking this will give sufficient strength to the half-round.

    And re getting a new piece of wood, I think you’d have to carve one.
    Neth and james condino like this.
  3. james condino

    james condino Spruce dork Supporting Member Commercial User

    Sep 30, 2007
    asheville, nc
    Please post a few photos for the visual folks!
    Neth likes this.
  4. dhergert

    dhergert Gold Supporting Member

    Jan 17, 2018
    Blue Zone, California
    My Alcoa's neck was repaired before I purchased it, so I don't have pics or vids. But I can tell you generally what I have been told was done...

    1) Remove everything from inside the neck and remove the fingerboard
    2) Discard these parts
    3) Straighten the neck
    4) Remove any bosses and weld the holes in the neck closed
    5) fit a 1/2" steel pipe the length of the inside of the neck space into an equal length wooden plug to replace the original wooden plug assembly
    6) Generously glue the pipe and wooden plug into the neck using a horribly pernicious aircraft-grade contact cement
    7) As the cement is drying, run a rod though the pipe and bolt it tightly through the neck ends at the pegbox and at the body (through an access panel in the driver-side C)
    8) HHG a foundational 1/4" layer of rosewood (probably Jatoba) to the wooden plug
    9) HHG a new rosewood (probably Jatoba) fingerboard to the foundational layer

    So the 1/2" steel pipe and rod are to keep the neck straight, the wooden plug is to glue the foundation and fingerboard to.

    My Alcoa also had an aluminum tear at the treble-side sound hole that had to be patched and welded from the inside, so the access panel was also installed for that reason.

    I don't necessarily endorse all that was done to make my Alcoa playable again, especially the use of the aircraft-grade contact cement, although I don't know what alternatives were available. I would guess that because of the glue used, if the neck on my Alcoa is ever bent again, it probably will not be repairable...

    But the neck is currently straight and it plays well. I do use low tension synthetic strings on this bass, primarily for tone, but I'm sure use of low tension strings also reduces stress on all of the repairs that have been done.
    Neth likes this.
  5. d, I know the guy who modified your bass.

    He’s a head case who does awful things to basses.

    I almost had a heart attack when I saw that door.
    Neth and dhergert like this.
  6. dhergert

    dhergert Gold Supporting Member

    Jan 17, 2018
    Blue Zone, California

    Yes, I understand. And I don't blame you.... When you and I first met here in TB/DB, I could almost hear from here while you were biting your tongue about the work that was done, trying not to extinguish my excitement. :D

    That said, there wasn't much double bass/aluminum expertise to be found within 200 miles at the time this work was done; or really within 2000 miles, considering that James is really the person to go to for this kind of work. And shipping wasn't a realistic option for the previous owner, so he took it to someone with a little DB experience, and a lot of aluminum / dune buggy fab experience.

    Long and short of it, this Alcoa was never going to be original again, and if it wasn't fixed it would have become a garden ornament within months as the aluminum top table continued to rip and the neck continued to bend under string tension. So from that standpoint it got fixed, it's stable, it's fairly fun to look at, and sounds and plays quite good for what I use it for. And of all things, one of the biggest attention getters is the trap door. Who would've thunk?

    But again, I don't blame you or anyone else who cringes at the repair work on my Alcoa. I do too sometimes. But I'm glad everybody has been pretty gentle, I'm still having the time of my life with it.

    Edit: He also glued the old cracked, wooden endpin plug in place with that aircraft-grade contact cement. The old plug is still going strong, but when it finally fails, I'll have to drill it out to fit the replacement plug and CF endpin that I've purchased. Ugh, that awful contact cement!!! :vomit:
    Last edited: Mar 7, 2020
    Neth likes this.
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