Post 24: Making the 12 Strings Bass 3

    After some tests on the backside of the 2x4, I gave up the idea of drilling holes larger than 1/2". But I placed them close together and staggered in 3 rows. I cut out most of the back, leaving just 3 crossties. I have a piece of 1/8" padouk that will make a nice lightweight cover plate. 

    I quite like the final result:

      It turned out easier than I thought to drill 6 holes through the body into the neck. I have temporary screws holding the thing together, that will be replaced by 4"+ through threaded rods with brass acorn nuts. 

      I ordered some brass/gold pickup covers, and some steel pick up plates. They were of course way too shiny for my taste. It actually took a lot of sanding to remove multiple layers of gold, nickel, and copper plating. Also, the brass covers were too small for my pickups, so I had to stretch them a bit and sand the plastic on the sides of the pickups to make them fit, but they came out looking great.

      To make the bridge adjustable in height, I made a 1/4" aluminum plate and fitted (barely) two of my 1/4" knurled brass screws. Two rod-piezo pickups will go between the aluminum plate and the brass bridge. 

     Time to assemble things and see if everything fits as planned. Final assembly with the nut in place and the strings tight will tell, but it seems that the bridge will probably need very little adjustment for the strings to be at the proper height above the fingerboard and the big frets I will be using. I might actually make the nut adjustable too. 

      The acoustic guitar PreampEqualizer is a tight fit at the end of the 2x4, which will be cut with the matching curve. The pots will get large knurled aluminum knobs. I am well pleased with the look:

         Now, putting the strings on this thing turned out to be quite a challenge, as both the anchor block for the strings at the head and the tuning system at the bridge gave me problems. I finally got all strings on and tuned to test it, and it works fine, but I am going to have to do some more work on both. 

       At first, I only used two M3 screws to attach the brass strip holding the tuning screws to a slanted aluminum base, and they were pulled by the tension of the 12 strings, so I had to modify it and use four screws with washers and nuts.  After full assembly and stringing, I could see the slanted plate was too narrow and too slanted, and I will replace it with one that supports the 12 small brass string holders.

       At the other end, my hard steel tightening screws ended up breaking a number of strings, and I had to use small pieces of brass rod as fillers and spacers.  They had to be tightened very hard, and some threads stripped. I rethreaded bigger, but that doesn't look so good.  Also, I never managed to get out the small drill bit I broke in there and had to drill another hole next to it. The entire brass anchor block system needs to be redesigned and modified to be gentler on the strings. I should probably add a cover to hide the ends of the strings;  unless of course  I just snip them really short.