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Bass banjo build, much advice needed

Discussion in 'Luthier's Corner' started by mandolinistry, Nov 13, 2018.

  1. mandolinistry


    Nov 13, 2018
    Hi all!

    So I recently got a free kick drum on Craigslist. Its about 24" wide. My bass player friend and I have had this concept percolating for a while, as we both play banjo as well and wanted to make a ridiculous monster of an instrument.

    I was hoping I could get some advice on my concept, since I am planning to mostly use upright bass components on this Frankenstein monster.

    This was parsed together from a bunch of different builds and sources online. Most were just random videos of the thing in action with no details.

    My plan is to cut the drum shell down to a more appropriate depth. Probably slightly deeper than the foot of the neck is wide.

    Internally, I plan to place 2 truss rods. On the bottom end of the shell, these will pass through just enough to attach a nut. There will be a metal plate each on the inside and outside of the shell to act like a washer and support, with a nut on the inside of each rod as well. In between the two would be the hole for the endpin.

    These rods will meet another plate at the top of the shell. Here I suspect I will have to use double ended nuts and connect to a second set of shorter rods which will pass through the plate and the shell, and into the neck assembly.

    Ideally I want to use an upright bass neck, and drill a hole in it for each rod. The concept I have now is one rod goes several inches into the body of the neck, and the second rod comes out of the foot where it is bolted down.

    Inside the drum shell I plan to have a support for the bridge. My current concept for this is a flat piece of wood which is attached to the sides of the shell while also sitting across the front truss rod. Essentially picture an upside down cross inside the shell.

    The bridge and tail piece would be double bass parts as well, with the tailpiece attached to the endpin as is standard.

    I've seen some designs that have an extra support bar on the outside of the shell, running from rim to rim under the tailpiece to hold it up, and some that have a third similar support under the fretboard, but I am unclear as to how critical these are.

    That is the rough working concept I have now.
  2. Will_White


    Jul 1, 2011
    Salem, OR
    Do you want to play it as a bass guitar or as an upright bass?
    chinjazz likes this.
  3. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Have a look at Banjozilla, my own crazy upright bass banjo:

    Bass Banjo

    The first problem with your concept is that an upright bass neck is about a foot too short. You'll have to either radically modify it, or make up your neck from scratch. An upright bass normally has a 42" scale length. Banjozilla is 40", and you can see how long its neck had to be.

    Yes, you'll need to put some kind of support system under the bridge. The head won't carry the load by itself. But that support system needs to be loaded by heavy springs, so it can move up and down, moving the head and creating sound.

    Banjozilla's rim uses a 24" head, and is 8" deep. The back rim is 28" diameter.
  4. mandolinistry


    Nov 13, 2018
    I expect it will be played like an upright bass, given the massive drum size.
  5. rudy4444


    Mar 13, 2012
    Central Illinois
  6. mandolinistry


    Nov 13, 2018
  7. Parker S

    Parker S

    Nov 25, 2018
    I just came across this, so going to throw in my two cents.

    I made mine using an existing banjo resonator and attaching the bass neck.

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