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The Fraternal Twin ...

Discussion in 'Luthier's Corner' started by CH Design, Oct 28, 2012.

  1. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    A while ago I said that I was going to be making a set of twin basses. Now that the first is finished (details can be found here: http://www.talkbass.com/forum/f57/first-build-sc5-headless-805307/). Sorry about all of the pics. I reorganized my Photobucket and all of the links were broken in my previous threads.


    Now it's time to think about it's twin.



    I already had the body mostly finished (top and back glued on, trimmed and routed to shape, bridge and pickup routes complete), but after spending some time playing my first, I found that there were a few thing that I wish I had done differently.


    One of of the things I wish I had done differently relates to the body thickness. The original body finished at 1.90" thick. I had originally wanted a thicker body to help give it some weight since the body is so small. However, the first twin finished a little heavier than I expected, so I wanted to take a little weight out on the second.

    I also wanted to angle the body to bring the reach to the first position back a little so you didn't have to reach as far forward. I did this on another bass and found it made it feel much more comfortable.

    But, how can I make these changes at this stage in the build? I had some thinking to do...
  2. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    It would have been easy enough just to plane off the back at the right angle, but then I would loose the Chechen on the back. This wouldn't have been so bad if the Maple under it looked good, but you can tell by looking at the pic above the the grain in the neck pocket doesn't line up on the two halves along the seam. I also don't have any more Chechen to make another back.

    So the obvious (well, obvious to me) thing to do was to cut the back off, cut the maple core at the desired angle and glue the back back on. Seems simple enough, right?

    I started by using double sided tape to stick the body to a large flat and piece of wood to make it easier to guide through the bandsaw.



    It was a little difficult to make the cut because I had to stand beside the blade in order to see how straight the cut was. In the end it didn't turn out too bad.



    I then proceeded to run both pieces through a thickness sander to clean up the faces.



    The back needs another pass or two to get rid of all the maple.


  3. I'm confused- if these are bolt-ons, why not simply angle the neck heel for whatever neck angle you want?

    Edit: Beyond that, VERY nice. Digging the minimalist bodies.
  4. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    Next I prepared to cut the angle on the body. I have a fixture that I use with a router on a sled to cut the right angle and a template to make sure the body sits properly in the fixture.



    Almost done ...


    And this is what the mating surfaces look like after a little scrapping and sanding. They have been wiped down with mineral spirits to clean the dust off before I glue them back together.

  5. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    Good question.

    I cut a 1 degree taper on the body. I think that's a lot more than you could angle the neck pocket.

    The other reason is that I prefer to keep the strings close to the body. I don't like a lot of room in there. By putting even a small angle on the neck you lift the strings up higher off of the body.

    I do also angle the back side of the neck (0.3 degrees). On my first "twin" I angled the entire back of the neck before gluing it on the body. The strings were a little higher off the body than I wanted. For this bass I plan on leaving the back of the neck flat where it joins the body and only angling the length of neck past the body joint.

    The design isn't mine. All credit goes to Adam at Beauchene Implements. He designed the body. It was his build thread on TB (along with a few others) that got me thinking about building. Adam was kind enough to let me build a set of twins using his design.
  6. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    Here is what the pieces should look like after they are glued. The back is a little smaller because I had already rounded over the back edge.


    Because I don't have any extra material that will end up being cut away, I don't have any spots where I can pin the parts together so they don't move while they are being glued together. I took my time and tried to make sure the parts didn't slip. This is how it turned out.


    As you can see, it did end up moving a little towards the upper horn. Other than the joints on the back and body not lining up, I don't think it's too bad.

    My router won't take a roundover bit large enough to clean up the edge, so I had to cut a 45 degree chamfer on the edge. I actually like the look of chamfers so I didn't mind having to make the change.



    Wetted with mineral spirits ...

  7. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    This shows the angle on the body.


    I put my neck template on the body and lined it up beside the first twin. The body angle brings the end of the neck back about 1 inch.


  8. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    So now I have a chamfer on the back and a roundover on the front. After looking at it for a while, I decided that I'd like it better if both edges looked the same. However, I already have the cutout for the tuners and neck pocket finished. That means that I don't have a complete surface around the edge of the body to use a bit with a top mounted bearing.

    I made some filler pieces to fill in these areas so that I could cut the chamfer. I started by making a filler piece out of some scrap walnut for the neck pocket. It was held in place with double sided tape.


    I used a flush trim bit to cut it flush with the body.


    Next up was a piece for the bridge cut out. This was a little more difficult to make as I didn't have the right router bits to make a piece that matched the cutout perfectly. There was one spot near the end that was a little off, but think it will be ok. It was trimmed with a flush trim bit as well.

  9. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    Now I can put the chamfer on the top edge.




    There is one small wiggle near the bridge cutout, but it's nothing that can't be fixed with some sandpaper later on.


  10. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    I plan on making changes to the rest of the design as well.

    Unless I run into problems fitting the neck to the neck pocket (again ...) I'm only going to use a bridge pickup (Nordstrand DC, black plastic cover) wired straight to the output (no electronics and no electronics cavity).

    I'm still undecided about the neck and fingerboard. However, I think I'd like to have the fingerboard run the entire length of the neck which brings it up around the 34th fret position. The only fingerboard I have that is long enough right now is a piece of Macasser Ebony. It has a lot of colour in it though, so I'm not sure I like the way it looks.


    My other options (without having to buy any more wood) is a Wenge fingerboard, which I'd probably pair with a one piece Wenge neck. I think it looks better, but I am really happy with the way the Ebony looks, feels and sounds on the first twin.


    As with my first build, I'm not in a hurry to get this finished so I have lots of time to figure out how to proceed.

    Edit: I was just looking at the pic that has the neck template on the body. It makes me think that a nice birds eye or flame maple fingerboard would look really nice. That would mean I'd have to coat it in epoxy if I want to make this one fretless too. Hmmm...
  11. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    I stopped by my local wood supplier today. I think I've found a winner for the fingerboard. Here are the options (wetted down to make them look a little more like they would after being oiled).


    Macasser Ebony

    Rosewood (East Indian I think)

    Flame Maple



    African Blackwood


    I have my favorites. What are yours?
  12. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars

    My vote would be the maple board, with the blackwood in a close second. None of the others look good with the body wood to my eye. The maple and blackwood have a nice contrast to the body woods, the others look out of place. A darker piece of wenge or Mac ebony would look good.

    The Ipe and Bloodwood look awful with that body wood IMHO
  13. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    We think alike. I'm trying to see if I can get a Flame or Birds Eye Maple stabilized board from Larry @ Gallery Hardwood. The board I have isn't long enough.

    I was hoping the Ipe would look better. It's a really great looking piece of wood. I'll just have to use it on something else.
  14. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    I decided on the African Blackwood and a QS Red Oak neck. I didn't go with an Ash or Maple neck because I don't like the look of two similarity coloured woods laminated together. I think the Oak is just different enough from the Maple body to look good. I also like to be different, so I figured I would give Oak a try.


    I'll glue that piece of Chechen on the back of the neck to make the volute (after I trim the knot out).

  15. Did you make the pickup covers?

  16. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    Yes and no. I had a friend machine them on a CNC mill. I did the CAD, wood working and finishing though.
  17. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    I have a small problem. For some reason the pocket for the neck is just a bit too big. It's not bad along the sides, but I can see a little gap at the end when I test fit my neck template. Any suggestions on how to get a better fit?
  18. If you havent cut the neck yet, Just make it a 1/32 oversize at the body and recut the pocket slightly.
  19. CH Design

    CH Design Supporting Member

    Apr 25, 2007
    Ottawa, ON
    Sounds simple enough, but how. I'm a simple use a template and patter bit on a router kind of guy. If I could find a bearing for my pattern bit that was slightly oversized it would be easy, but I haven't been able to find one yet.
  20. Add a few layers of tape to the template til you have enough thickness to make up the gap.