new way to build CBG

Posted by Tim Gale on July 7, 2010 at 3:07am
The problem when building a CBG is that you have to run the neck through the box for structural strength. As the boxes are already small, this eats up a lot of the available volume for producing good sound.  My latest build I glued a threaded rod into the neck.  Drilled holes on each end.  Cut a length of square, steel tubing to fit tight inside the box.  I put pieces of aluminum in the ends for added strength.
Then you put all together and tighten the nut on the end.  The steel tube is very strong and does not need to be very big so you don't take up so much space within the box.  Look at the pics, they say it all.  Only two small holes to drill in the box too. 

parts.JPG

side view.JPG

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Replies

  • Murray July 9, 2010 at 8:42pm
    Yeah! I would love to see an archtop CGB, or the closest thing to it anyway :O)...

    I had the silly thought this week about a Selmer Maccaferri orchestral CGB...but maybe after I get some experience...;O)
  • Tim Gale July 9, 2010 at 6:28pm
    Sure, I'd love to see some pics of what you did. I think I solved the rod strength issue by running it through the square tube. This way the stress is not on the box, but on the square tube and the aluminum end pieces.

    Christopher said:
    I did build one with threaded rod. It started when I messed up the neck :) I epoxied a rod into the end of the neck (pretty much like you did). I did have some issues with the strength of the rod initially but I dealt with that by raising the neck high over the box (like an archtop). the box acts as a brace. I'll post some pics up on page if you like.


    Jeremiah Cornelius said:
    This was how my brother built his previous - a 4-string CBG with a high bridge and raised neck, like a jazz archtop.

    He didn't cover the rod with a square extrusion, but the rest of his technique was about the same as this - simple and sturdy.

    If you ask nice, he can probably contribute some insight I don't have, and he may even be able to add photos on his personal page.
  • Christopher July 9, 2010 at 4:32pm
    I did build one with threaded rod. It started when I messed up the neck :) I epoxied a rod into the end of the neck (pretty much like you did). I did have some issues with the strength of the rod initially but I dealt with that by raising the neck high over the box (like an archtop). the box acts as a brace. I'll post some pics up on page if you like.


    Jeremiah Cornelius said:
    This was how my brother built his previous - a 4-string CBG with a high bridge and raised neck, like a jazz archtop.

    He didn't cover the rod with a square extrusion, but the rest of his technique was about the same as this - simple and sturdy.

    If you ask nice, he can probably contribute some insight I don't have, and he may even be able to add photos on his personal page.
  • Tim Gale July 8, 2010 at 7:48pm
    I'd love to see pics of what he did and any thoughts or suggestions.

    Jeremiah Cornelius said:
    This was how my brother built his previous - a 4-string CBG with a high bridge and raised neck, like a jazz archtop.

    He didn't cover the rod with a square extrusion, but the rest of his technique was about the same as this - simple and sturdy.

    If you ask nice, he can probably contribute some insight I don't have, and he may even be able to add photos on his personal page.
  • Jeremiah Cornelius July 8, 2010 at 3:49pm
    This was how my brother built his previous - a 4-string CBG with a high bridge and raised neck, like a jazz archtop.

    He didn't cover the rod with a square extrusion, but the rest of his technique was about the same as this - simple and sturdy.

    If you ask nice, he can probably contribute some insight I don't have, and he may even be able to add photos on his personal page.
  • Tracy Kennedy July 7, 2010 at 5:02pm
    This is a wonderful idea you have come up with Tim,

    You would want to consider JB Welding or epoxying the tube and aluminum plates together in place so you wouldnt even have to open the box to install a new neck

    As far as the neck being adjustable in the back it would obviously require a vertical slot. You also might consider a blank that would fit the unused / open portion of the slot, even when the nut is tightened the neck cordinator rod could still slip out of place, taking the action out of adjustment. A blank to fill the void would prevent that.

    Tim Gale said:
    The other thought I had with this is that you could make interchangeable necks. If you had a really nice box that had great sound, you could make a three string neck and a four string neck and just swap them out.
  • Tim Gale July 7, 2010 at 12:29pm
    The other thought I had with this is that you could make interchangeable necks. If you had a really nice box that had great sound, you could make a three string neck and a four string neck and just swap them out.
  • Tim Gale July 7, 2010 at 12:27pm
    The slot idea is something I had not thought of. It might just work. Don't know till you try. Right now the aluminum pieces are just held in place by the pressure. I made the tube very snug so when you tighten the nut it wouldn't make the walls of the box cave in. I will probably glue them in place when I am finished.

    David Lloyd said:
    Hi Tim,

    A really neat idea - I am thinking of doing a biscuit tin banjo in the future and was trying to think of a good way to do this after seeing this website on coordinator rods http://europa.spaceports.com/~fishbake/banjo/coord/coor.htm. Your way seems a much better technique. Do you think if the tightening nut at the tail end was put through a slot (so the neck could be moved slightly to alter string action- the neck end being a pivot and the tail nut lifted or lowered) it would still be strong enough to work? Also the aluminium parts you have added to each end are these glued or welded in place?

    Great job,
    David
  • MichaelS Country Boy Guitars July 7, 2010 at 12:22pm
    This is neat, always a new idea for neck mounting.
  • Mark July 7, 2010 at 6:00am
    A very interesting design - and nicely executed.

    How are the pieces of aluminium fixed in place? Are they attached to the box or fixed to the steel tube or are they just held in place by the force of being sandwiched between the other components?
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