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5-string Electro-acoustic

Discussion in 'Luthier's Corner' started by Dave Higham, Jan 21, 2012.

  1. Dave Higham

    Dave Higham

    Dec 19, 2005
    I haven't contributed much to this forum yet so I thought I’d do a build thread. This is the third bass I made but the first one where I took photos of the construction, although there were moments when I forgot so there’ll be a few holes in the sequence. It has been seen on other luthiery forums so some of you might already have seen it.
    First I should say that the only thing acoustic about it is its appearance. If you don't plug it in you can't hear it.
    Second, is that it owes a lot to Rick Turner's Renaissance basses although I did change the body-shape and quite a lot of other things.
    So here's how it started. I'm sorry, most of the photos are a bit on the small side and were taken on a crappy old digital camera.

    It's what I believe is called a 335 construction, which means there's a solid block in the middle of the body. My block is part mahogany, part cedar because I didn't have anything big enough in one piece. The little sandwich on top of it is cedar/maple/mahogany. You'll see what that's for later.

    Little sandwich glued to big sandwich. The small holes were for dowels (I use 5mm brass rod) to stop things sliding about when glueing. For the little sandwich I used toothpicks to keep it in place.

    Hogging out some unnecessary weight.

    I made a plywood template and stuck it to the block to clean up the cavities with the router. (you see? I already forgot to take the photo) The cavities are mainly to reduce weight but also to reduce gluing area for the top and back. The mahogany is at the back, by the way. Although you can't see it very well, the ends have been profiled to the shape of the body. The white bits are paper. I draw up my instruments on CAD then, if I need to shape a profile, I print out that bit of the plan, stick it to the wood with spray adhesive and shape up to the line. The block also has a tapered slot, cut on the table saw. This will be for attaching the treble side rib. (Quite a lot of missed photo opportunities!)

    Although this looks almost the same as the last photo, you'll see that the block has been tapered in thickness and the surface has been sanded in a 15' radius sanding dish (more missing photos).

    Well, that'll do for a start. More soon.
  2. Skelf


    Apr 15, 2005
    Moffat D&G Scotland
    Builder AC Guitars.
    Nice work Dave always enjoy your work.
  3. Dave Higham

    Dave Higham

    Dec 19, 2005
    Thanks Alan. Nice to hear from you.
  4. gitlvr


    Nov 13, 2009
    No. Va., USA
    Keep it coming!
  5. Curious and subscribed :smug:
  6. Curious and subscribed :smug:
  7. Dave Higham

    Dave Higham

    Dec 19, 2005
    Ok Here's another installment

    This is the widget bracket glued and screwed in place. It needed the bit of 1mm ply behind it to align it perfectly with the hole. I made it from a nut like the one you can see, that I managed to scrounge somewhere.;) What's it for?..."patience Grasshopper"....all will be revealed.

    This is the wedge that will hold the rib in place on the treble side. The method’s borrowed from Classic guitar construction. I believe Jose Romanillos invented it.

    Here it is dry-fitted using an off-cut of the rib.

    I should have mentioned that the body is an asymmetric shape. The treble side is shorter than the bass, so a piece of rib material has to be glued on which is what is happening here.

    The slots have been cut for the 'braces'. I'm not sure they were absolutely necessary but Rick does something similar so I did too. A hole has also been drilled to connect the treble side with the bass once the box is closed up.

    Here's the block with its so-called braces fitted (dry).

    I used a home-made Fox-type bender to bend the sides after thinning them to 2mm (.080”) but, of course, I had to make 2 bending forms. Anyway I got them bent and here they are, although you can't see them, in the funny shaped mould. There wasn't as much spring back as the number of clamps might lead you to believe.

    This is a bit more interesting. I decided to used a D-Tar pickup because that's what Rick puts in his basses (although I'd never played or heard one for real) but I thought, if it's good enough for Rick... (well, obviously it’s good enough for him, he designed it and Seymour Duncan makes it). When I bought it they were powered by two 9-volt batteries and they have a preamp attached to an end pin jack socket. As I have a centre block I decided to make 2 access traps in the butt of the body. Cutting them out generated equal amounts of perspiration and bad language! The way I did it, (no photo again) was I made a stainless steel plate the same size as the cut-out and stuck it to the rib with double sided tape. I then drilled a hole with the tiniest drill I could find just touching the plate and cut out the trap with the fret-saw, keeping the blade in contact with the s/s plate all the way round. It ruined the blade, of course, but worked out quite well.

    Here the ribs are being glued to the centre block. As you'll see in the next photo, the mould has a removable section in the end which made the glue-up easier. The wedge was also glued in to hold the treble-side rib in place.

    And, at last, it's starting to look something like a guitar shaped object.

    More later and, if you have been, thanks for watching.
  8. aronnes71


    Jan 4, 2010
    Alta, Norway
    Nice build, subbed!
  9. This is an amazing build, never seen this bottom up approach of building an acoustic bass, very interesting and wonderful execution.
  10. ctmullins

    ctmullins fueled by beer and coconut Gold Supporting Member

    Apr 18, 2008
    MS Gulf Coast
    I'm highly opinionated and extremely self-assured
    Beautiful work so far! Thanks for making me feel like an inept hack..... ;)
  11. monkeyking


    Feb 6, 2009
    Tremendous so far! This will be a really interesting build to watch.
  12. PaPaVB20


    Aug 19, 2008
    Totally interested in this thread... Great stuff, thanks for sharing
  13. Stealth


    Feb 5, 2008
    Zagreb, Croatia
    Very cool build. Subbed.
  14. Dave Higham

    Dave Higham

    Dec 19, 2005
    Thanks for the kind words folks, they are much appreciated. By the way Rob, as I said earlier, the only thing acoustic about it is the appearance and some of the construction methods. Here’s another instalment.

    Well, those access panels need something to screw them to so here is a block being glued into the treble side of the body. You can see the other one, for the bass side, behind the mould on the bench.

    Here’s the supporting block glued in place.

    And here’s a closer view of it with the access panel which also has a block glued to the back of it.

    So now it was time to make sure that the preamp and battery holders fitted without interfering with anything else. Although it's not clear from the photo, I made a piece of aluminium sheet bent at right angles which I screwed to the access panel and the battery holders are screwed to the aluminium (aluminum if you’re on the wrong side of the pond ;)).

    View from the outside. The jack socket on the preamp is fitted to an Electrosocket. I used one on a solid body before and I like them.
  15. Amazing! Can't figure out the purpose of the 'widget bracket'.. running out of patience :bag:

    Yeah, true, won't be an actual acoustic, more like a semi-acoustic, but I still fancy this approach :smug:.
  16. Wow! interesting... subb'd.
  17. MPU


    Sep 21, 2004
    Valkeala Finland
    Sure looks very interesting. I guess the "gadget" is some sort of strap button extension.
  18. loov it. more pics!
  19. charlie monroe

    charlie monroe Gold Supporting Member

    Feb 14, 2011
    Buffalo, NY
    This is beautiful. I am a big fan of things that are not as they appear, so an 'acoustic' bass that requires amplification is right up my alley.

    I am going to guess that the widget is for receiving pots or switches. I will even go further by suggesting it may be for a stacked Vol/Tone pot. This would leave the face of the bass completely clear of everything but bridge and strings.

    ...BTW, subbed.
  20. Dave Higham

    Dave Higham

    Dec 19, 2005
    Sorry Charlie, I know Rick Turner puts a Vol and Tone control there but Marko sussed it out. But we're not quite there yet. First I have to install the linings to give the front and back something to glue to as well as the centre block.

    These are reverse kerfed linings. For anyone who might not know, the linings are the strips of wood glued to the sides (sometimes called ribs) to increase the gluing area for front and back. Some people call them kerfings which annoys some other people because the kerfs are the saw-cuts which make them easier to bend. Reverse kerfed means you glue the kerfed side to the ribs instead of the smooth side, which was the traditional way. This makes the sides much more rigid as it forms a sort of box section. I think Charles Fox was the first to do this. Sorry if I’m preaching to the choir here.

    Letting the 'braces' into the linings. I remember now what the braces were for. Because of the centre block, I couldn't use the usual system of cauls, etc on the inside to keep the ribs in position when gluing on the back and the top. The braces, which are glued in before the back and top are fitted, keep the sides in place. I also decided to double the linings as well as adding a strip of 1mm birch ply. This made the ribs very stiff and they kept their shape perfectly when taken out of the mould so I could perhaps have dispensed with the braces.

    A few more things I forgot to photograph. Before fitting the front braces which you see here, I glued two pieces of cedar onto the centre block, one either side of where the sound hole would be if it had one. I also routed the cavities you can see, apart from the round one which was routed after the braces were glued in. The two blocks for the access panels were also relieved to give a more or less even gluing area everywhere.

    I'll explain what the widget does in the next episode.
    Thanks for watching.

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