Spending ÃÂÃÂ£400 on a Kala Ubass is a big commitment, and as a young adult I simply don't have the money to invest. This is a simple conversion as originally conceived by Olivergon on this.
What you need:
Donor guitar- can be 1/2 or 3/4 size as long as the scale length is correct. Ideally 20-21" but anything between 18-25" is okay. You will need to order the strings.
Pahoehoe or thundergut strings- Pahoehoe do the 18-25" lengths, and these are what I used.
Bass tuners- or you can widen the holes in the original tuners with a drill if they are similar to the tuners shown on mine
Brill bits- 1mm for pilot holes, and 5.5mm for the string holes, you'll need good HSS bits if your widening the pegs if thy are like mine, mine had some pretty hard brass that needed to be wasted.
Step 1: Order Strings
You'll need to get some short scale bass strings, whether they are Pahoehoe strings (www.roadtoadmusic.com) or Aquila Thundergut strings from EBay or Amazon.
Order these first because you need them to sort out your nut and bridge setup.
Step 2: Prepping the Guitar
Remove the strings and the tuners, quite simply with a wire cutter and a screwdriver.
Step 3: Put on the Bass Tuners
Again, simply attach whatever bass tuners you've gone and bought. As long as they are stable it should be okay. I actually widened the holes in the original tuners with a drill to hold the string. This is risky, I broke 4 of the pegs when I was doing it.
Step 4: Measure Out the Indents for the Nut
You'll need to measure ye width if the strings, add them up. Add the space you want from each side and divide by three for the spacings. If you don't do this the 3rd and 4th string will be quite close together, which is not ideal.
Step 5: Drill the Holes in the Bridge
Again you'll need your measurements to ensure ideal spacing. Ideally you'll want holes of 5.5mm, but 5mm will do.
Step 6: Electronics (optional)
Order your bits- you'll need a guitar preamp thing as shown.
Mark and cut your holes
Drill a hole in your bridge for the piezo wire to feed through.
Measure the height of the piezo piece and file/sand away as much off the bridge.
Insert everything appropriately and connect them up, and then hopefully up can test it by tapping on the bridge.
Step 7: Attach the Strings
Use a washer and tie a knot in the end of the string. With pahoehoe strings they have a thing like a small washer so you need need to on these.
Thread this up from inside your guitar. At the tuners, you may want to decide whether the string wraps from the outside or the inside for the best string alignment.
You'll have to to stretch out the strings other wise they'll end up jumping over the top of the tuning peg. What I did was pull it so it was close to the string note. And then, with some effort, force it into the tuner. (For the 1st and 2nd string, no need for the classical tuners)