Introduction: DIY Bass Uke
What is a Bass Uke?
Merely a copy of the bestseller Kala UBASS, which is a short scale bass guitar in the body of an ukulele. The main component of this special bass is the string material. The strings are based in the silicon strings used by the Ashbory, later evolved to polyurethane strings when Kala launched their Kala UBASS; and Aquila has its own version of these strings called Thundergut.
The idea came to me after seeing a 3/4 classical guitar at a local shop. After comparing side by side with a Kala UBASS, I discovered to my surprise that the scale length (distance between the frets) was the same, so I had a donor to begin my DIY Bass Uke.
Note than this instrument is not a real ukelele, neither the UBASS. When Kala introduced the UBASS, they used an uke body shape because they are a ukulele brand, thus only for marketing reasons.
- 3/4 classical or steel string guitar
- Aquila Thundergut set of strings
- Bass guitar tuners
- Electric drill and wood drill-bits
- Small rat file
Step 1: Select a Good Donor Instrument
I found a cheap guitar at 35EUR which had the same scale length of the Kala UBASS, so it was the perfect donor guitar.
Other guitars may work, but the thing is that you must go for a guitar with a suitable string length for the polyurethane strings, or it will not work.
The proper string length is around 560 mm.
Step 2: Assembling the Tuners
First you have to remove the old tuners.
Then I just realized that it would be better if the outer strings were looped from the outside, so there is better string alignment.
At the beginning I though I would cover the holes, put a face veneer or something like that, etc. But later decided that this should be a DIY approach, and would be better to leave a rude look.
Take care when assembling the bass guitar tuners, because with minor rotations, you can be able to fix them with three or four screws.
Also notice that the two tuners for the first and fourth strings are reversed and offset (because there was not enough space).
Step 3: Measuring
Begin by measuring the nut and bridge saddle length, which in my guitar was 45 and 70 mm.
Then, you have to measure the strings diameter. The Aquila Thundergut strings are 2,5mm, 3mm, 4mm and 5mm.
I decided to leave 5 mm from the outside of each string to the nut and saddle.
2,5+3+4+5 = 14,5 mm is the space taken by the strings
14,5+5+5 = 24,5 mm, is the total space needed for the strings and free space at each end.
At the nut, the string spacing should be = (45 - 24,5) / 3 = 6,83 mm
At the bridge saddle the string spacing should be = (70 - 24,5) / 3 = 15,16 mm
Why to make all these numbers?
Because we want to have the same free space between each of the strings. If we don´t consider the string diameter, then the centerline of the strings would be equally spaced, but the third and fourth would be closer that the first and second.
Make a template in a piece of paper with all the measures and tape it to the fretboard right next to the nut, and do the same at the brigde. Prior to fixing the bridge template mark the centerline of the place where the strings are tied.
Test with a real string if the templates are right, and if the alignment is ok with the fretboard. Remember that it´s better to check three times before cutting.
Step 4: Make the Holes at the Bridge
I used a battery hand drill with a 1mm drill-bit to make all the bridge holes. Then I enlarged the holes with a drill-bit which was 0,5mm wider that the strings. If you don´t have so many drill-bits, you can just make 5 mm holes for the four strings.
After making the holes, it was obvious that the string angle was not very good so I had to file a ramp.
Also discovered that under these innocent pearl dots, a fixing screw was hiden ;)
CAUTION: I used a black marker to paint the hole inside, and was not cautious to wait until the ink dried, so I ended with a tinted string. Wait a few minutes before inserting the strings.
Step 5: Insert the Strings
The strings go from the inside to the outside. In the Kala UBASS there is a cover at the back to be able to insert the strings from the inside, but I preferred to make it the other way and make my own knot with a washer just to ensure a better contact.
The slots at the bass tuners are not wide enough for the 5mm string so I had to file it a little bit. After some fight, the string was inside the tuner slot with enough pressure that ensures it will not slip or go out.
For the first string, I was able to make a double knot.
And voilá, you can see the four strings attached, seeing how the two outside strings are rolled from the outside and the other two by the inside.
NOTE: The black dirty marks on the fourth string are the result of not waiting the ink to dry before inserting the string in the bridge.
Step 6: How It Sounds?
At this moment I just finished the assembly, and I´m waiting the strings to settle and stabilize the tuning.
In a few days I will post a video comparing the original Kala UBASS and my DIY Bass Uke.
Thanks and hope you are able to make your own version.
You can follow me on my Ukulele Facebook Page and see my other uke things on my Ukelele website in spanish