Introduction: Designing and Making a Bass Ukulele
The aim of this instructable is to go through all the steps necessary to design and build a bass ukulele starting from some blocks of wood and ending with a finished instrument.
Here is a quick preview of what it sounds like.
Step 1: Basic Design
Your scale length will be dependant on the strings you get (or you will have to get strings dependant on your design). The strings I have (Aquila Thunderguts) say they are made for basses with a scale length of 18 to 21 inches. I do all my best design using CAD - or Cardboard Aided Design using ruler paper and pencil and scissors/knife. This neck template has a bit of cardboard extra at the top for attaching the headstock template to and the rest is to lay on the body.
It is, (as you can see from what is written on it,) 45ish mm wide at the nut, has a scale length of 514mm (20inches) to which around 10mm compensation is added at the saddle/bridge. Another 20 or 30 mm may be needed to give wiggle room for the adjustable/ floating bridge (fixed is OK for fretless). The saddle is at least 70mm wide to fit the acoustic bass piezo pickup.
After a few tense minutes looking at the length of the G string I decided to forego a little length and aimed for a 485 mm scale length.
Step 2: Things Done Previously
I have made a couple of solid bodies, which are simpler than hollow bodies but because hollow body bass ukes are so quiet there is not much volume difference. I downloaded and adjusted templates from a site that has since been deleted. This alternative site has a great variety if not as many versions of the same models like the old site did https://www.electricherald.com/guitar-templates/
The Fenwick Rodmaster is a 90% jazzmasterish bass with the neck join fiddled to fit a 100% neck width. The Chanenbacker is a full sized Rickenbackerish body.
As you may be able to see from the Fenwick Rodmaster bass the strings I have are a little tricky with the four to a side tuners as the G string is the shortest one in the set and has to go the longest distance. Most bass ukes have two tuners per side like the Chanenbacker.
Step 3: Parts
You will need to buy some parts - I haven't got them all in this photo and not all of them are absolutely essential.
In the picture:
- top left a pre-wired passive volume tone control or variant (not strictly necessary at all) I have used active control circuits in all my builds there are plenty of active and passive controllers and preamps available. I much prefer the final look of the bass active preamp I used for the Rodmaster rather than the sit in top box preamp I put on the Chanenbacker. Some of these active preamps include tuners which some people find handy.
- second from left an acoustic bass piezo pickup (it is about 70mm wide and has 4 big lumps which are the individual pickups for each string). I have seen people build cigar box guitar basses with only disc piezos. I have heard it told that the rod version is better.
- third from left, a Fender style neck attachment plate (optional - this build is going to be a stick through and other designs are also possible),
- bottom - A set of open tuners for a regular bass (this type can be easily flipped left or right the far right one has been disassembled) or you can splurge on the purpose built bass ukulele tuners.
Far right - something to quickly and easily widen those slots to fit the thick bass uke strings - this 2 inch diamond wheel is a little flimsy but eventually does the trick (if you did splurge on the purpose built tuning pegs you won't need this). As you can see from the next picture I fitted each of the tuners to one of the strings by process of progressive widening. It can be a lot of work to widen the slot so don't waste any more time than you need to. Since originally writing this instructible I switched to using a tile cutting blade in an angle grinder, which is considerably faster.
More to buy
- fret wire - I used 2.4 mm for the Fenwick Rodmaster or not - The Chanenbacker is fretless I have seen full bass size frets used which looks a little wrong for some reason.
- bass ukulele strings there are a wide variety of these and they need to be roughly matched with your planned scale length or vice versa.
- wood for neck and body,
- pick-guard material,
- nut and saddle material.
- string trees though I made my own from a small scrap of wood for the Rodmaster.
- Tools you might need - e.g. Fret slotting saw, forstner drill bits (14 and 18 mm for these tuning pegs), band saw or sabre saw, an axe and a potato peeler.
Step 4: Create a Body Blank
Unless you use some form of fabricated wood and I have heard of electric guitars made from MDF or plywood or you have some really big bits of wood you will probably need to glue up a body blank from smaller bits of wood. This wood is an old wardrobe door frame and is as close to a 2 by 4 DAR as you might like to find. It is 45 mm by 90 roughly though it is a little out of square and varnished and not quite flat. Because the middle part will be our neck as a through body I cut some preliminary shape into the neck profile. Because it has been sitting around holding on to some doors for about 40 years it should have done all the moving around it is likely to do so I didn't bother with additional strengthening like a truss rod or laminated neck.
You will need to work out how deep into the body you want your fretboard to be, this one joins the top part at the 14th fret which is fairly typical of steel string guitars.
Step 5: Mark Out Your Body and Neck.
Trace your templates out onto a neck and body. If you are making a neck through design this is done in one go. If you are making a two piece body and bolt/screw on neck then they are cut out separately. The advantages of a neck through design is overall simplicity and structural integrity. The advantages of a bolt/screw on neck is the adjustability, ability to mix different materials for neck and body and separation of bits to make mistakes on - if you ruin your headstock you haven't stuffed up the whole guitar, just the neck part. To make things easier to see, especially in the photos, and protect the surface I used masking tape. Because cardboard is not a premium template material I remeasured the neck dimensions directly onto my blank.
Because the 70% size body template notionally has a 70% width neck position I moved the body template to either side to get the beginnings of the line where the body meets the neck. after a great deal of head scratching I went over only the last 50 mm or so of that line merging it with the centred body line. You will see that the templates on the fenderish plan site has alignment lines roughly down the centre. Feel free to get creative with your own shape the shaping here is not critical as it does not influence much except looks. The Ashbory bass is an example of how little you need.
The body I finished up is from https://sites.google.com/site/guitarplanscollection/pdf-files in a file called Fenderjag-jazz.pdf in the fenderish collection. I used the poster printing and scaling options in acrobat reader to print a 70% scaled body. I started with a file in the Fenderheadstocks.pdf file and did a lot of fiddling to get a shape I was happy with and in the end I even made this version smaller again. Attached is a pdf of a scan of the cardboard template I used for my headstock..
Step 6: Cut Your Body Out
Now comes the fun part. Head over to your band saw or break out the jig saw and cut your body out.
Because I had not quite enough width in the 2 by 4 neck blank for the headstock I had to add a couple of off cuts
At this point I also did a bit of work to reduce the size of the headstock template, allowing only 44 mm for the tuners (which seem to vary between 42 and 44 mm long) rather than 47 mm as in the original template I got from the web site.
Step 7: Smoothing Off the Body and Making It a Little Thinner
I used my trusty stanley number 4 and a half to smooth off the front. Then I went a bit medieval on the back with my number 78 and removed about 6 mm of thickness which wasn't really needed. I could actually have thinned it further but I am fine with it at about 38 mm. I believe standard Fender thickness is 41 mm. A quick run with the orbital sander and sanding with some long boards to get the neck flat was also done and checked.
I did a lot of smoothing around the sides with a japanese shinto rasp and various sanding implements to get things flat or evenly curved and smooth.
Step 8: Headstock Angle
I toyed with the idea of a traditional Fender headstock with no neck angle but an offset of about 9 mm down but drifted to an alternate plan where I used the thickness of the 2 by 4 to give me just a little angle and an 18 mm thick headstock. This I cut close to width with the band saw and brought to the thickness with the small planes and sander.
Step 9: Making a Fretboard
Making a fretboard is the area of the guitar that will benefit the most from really accurate measuring.
I have a home made fret board duplicating jig that uses a commercially cut fretboard as a pattern for me to duplicate the fret locations on a pre-cut fretboard. It is simply made by cutting a U shape made from 3 bits of wood at right angles and putting a bit of snap off razor knife at the bottom to lock into the frets of the existing fretboard, which ensures that the frets I then cut in the top fretboard duplicate the ones in the bottom. Many fret slotting jigs go to a deal of trouble to ensure the depth of cut is uniform and deep enough for the fret tang. I use the startlingly simple method of stopping when I can no longer see light through the bottom of the saw teeth. Unfortunately, on this build I later noticed that the 2.4mm guitar fret wire has a longer fret tang than my regular 1.7mm ukulele fret wire so I had a bit of work to redo later. The saw I use is a standard dovetail saw. I started out many years ago using a junior hacksaw and you may find a saw you have laying around your shed may do the job. For example I only had to hammer flat the teeth of the regular hack saw blades a touch to flatten the set of the teeth and they worked well too. See the above set of test cuts I made using saws laying around my shed.
One of the magical things about fret boards is that if you start one fret down you have a fretboard that suits a guitar with a length one fret shorter. Most guitarists will be aware of the use of the capo which is a non- permanent application of this principle. In this case I used a standard 648mm scale length 26 fret fretboard given to me by a friend. By starting at fret 3 I have a fretboard that was a notional 514 mm scale length. One further down gives 485, which is what I have decided on for this current build to assuage my anxiety over the G string being the shortest string in the pack and the Fender style headstock making it the string that has to reach the longest.
At the top of the fretboard I make a small recess to put the nut in. All a nut is is a zero position fret which has slots in it to hold the strings in place, but now I have lectured you about capos and how I use the regular fretboard to make my shorter bass ukulele one you probably worked this out for yourself already.
Other ways to mark out fret spacing for any length of fretboard are :
to use the fret calculator at http://www.stewmac.com/FretCalculator
or print out a template from http://www.ekips.org/tools/guitar/fretfind2d/
This link will give you the parameters I think would make a good fretboard for a 512mm scale length Link to fretfind2d
If you are going to use the fretfind2d page you have to make sure you print your PDF at actual scale because some PDF readers default to shrinking over size pages or printing the browser window which can screw things up completely. It gives you an accurate scale, just a little shorter (or longer) than the one you thought you were printing. Printers have also been known to be slightly inaccurate. In either case double check that double the length between the "nut" and the 12th fret on the printout. If this is half of the scale length you thought you were getting you are good to go. If you are always cursing your printer because it gives you wonky looking printout, you probably should not be using it for this task. Some modern browsers will not let you fix things so you may have to save it to a separate location and open it up in an old fashioned pdf reader like Acrobat reader. I also had a slight issue with Acrobat flash player needing to be enabled when I tried to use it last time.
The old fashioned way - multiplying by 17/18ths or 1/18 depending which way you go. The more accurate old fashioned way multiplying by the 12th root of 1/2 (or 1 minus it as above) - this gives the same result as the Stewmac calculator.
If you don't quite feel up to buying fret wire, I have used split bamboo toothpicks superglued down and bent 50mm nail gun nails.
Most of these tips I got from the cigar box nation site.
Step 10: Adding a Fretboard Radius or Removing the Part That Is Not Radiused or Not
Many fretboards have a radiused fretboard which to my eye makes for them looking slightly more groovy and provide a different feel to how they play. I used a 12inch sanding radius block. To give myself a head start and to help keep the sanding process even I remove a little around the edges with a tiny block plane just eyeballing how much I needed to remove. I then trimmed the fretboard closer to the tapered width of the neck. Switching occasionally between the short radiusing block and a longer flat block to maintain longitudinal flatness, which is critical to playability.
Not radiusing saves a lot of work.
I like to literally drench my fretboards in shellac to help stabilize it and make the grain "pop" particularly when I use reddish hardwood timber decking (eg karri, jarrah, meranti) which though hard has a tendency to split and splinter. Others like to use super glue and most don't bother but use more select building materials. This fretboard is karri and benefits from the stabilisation.
Step 11: Pick Guards
I printed off the version of the body plan that had the pick guard template. The volume and tone knobs need to be about 25mm apart to stop them bumping into each other. I worked out that I didn't have enough room for the 3 volume/, tone knobs plus plug so I embigened the tail and cross checked using the templates that my bridge and pick guards would not interfere with each other and that my knobs would be in a convenient position. In particular that they would not finish up under the strings and the pick guard would not interfere with my predicted bridge position. I did all of this in paper and/or cardboard first. I could also have shifted the plug to a side or tail mount position. I also marked on the body where the bridge should go.
Step 12: Shaping the Body
Most solid body guitars and basses have at least a little bit of shaping to the body, perchance to make them easier to hold, have slightly less hard edges and lighter. Now I know where things like the bridge and pick guard are going to go I can hack away a bits where the bridge and pick guard are not. Mostly the part where your body is hollowed out slightly and where your arm goes is bevelled back a bit. Use whatever comes to hand. I picked up the little baby block plane and before I had time to think about grabbing a better tool I had already shaved off enough for the arm bevel. An axe is a little risky but it is quick and gets the job done if you have the skills and the courage. I use dumb stupid luck to prevent accidents. I cleaned it up a bit afterwards using my rasp and an random orbital sander.
Step 13: Gluing on the Fretboard
Cross check that all surfaces are flat. A couple of small nails are used to prevent the fret board from sliding about. I pre-drill 1.8 mm holes in the slots of the 3rd and 12th frets. These small holes will get covered when you put the frets on. The holes also helps me keep track of where the 3rd and 12th frets are for when I add fret dots later.
Add glue to both surfaces try not to get too much glue onto parts where you are not sticking the fretboard. Place the fret board carefully making sure it aligns with the nut and body joint intended positions you planned earlier. Hammer in your two alignment nails.
I then strap it down using a strip of bicycle inner tube. Anything like that such as surgical tubing or slightly stretchy string or rubber bands linked together should be fine though be careful not to get glue on the string. I have never had much problem with the inner tube rubber. I held the loose end with a spring clamp and clamped down the last bit of the fretboard over the body.
Wipe off excess glue squeeze out. Don't get too obsessive about wiping up the squeeze out, What you don't wipe up when it is wet you can remove with a scraper or sandpaper when it is dry.
After everything is dry remove clamping and nails and check flatness and scrape/sand off excess glue.
Step 14: Shaping the Neck
I like to do the final shaping of the neck after adding the fretboard but before adding the frets. My favourite tool for this job is a Y handled vegetable peeler. After shaping with this all I needed was a little bit of sanding but I have had a lot of practice with this thing and a lot of dumb stupid luck.
Here is a video of how well it works on a slightly less ambitious build.
Step 15: Add Fret Dots.
Here I have added some abalone shell fret dots at the 3 5 7 9 12 and 14th frets, front and sides. There is a surprising amount of debate over whether a dot needs to be at 9 or 10 and 14 or 15. I cut these ones from an abalone shell using a diamond core drill bit. I have used everything from knitting needles to BBQ skewers to screws to pyrography to dots punched out of plastic milk bottle lids or bread clips to stained epoxy to mark fret positions. These are really just bling for the audience. The side markers are what the player sees.
Step 16: Holes in the Headstock
To maintain accuracy I remeasured the spacing on the headstock so the tuners are 25 mm in, the first is 25 mm up from the turn at the bottom of the headstock and the holes 44 mm apart. This made the fit extremely tight and I had to file a half a mm off one of the tuners when fitting them due to a slight inaccuracy on my part. The grommets need an 18 mm hole and the shaft needs a 14 mm hole. To keep them aligned I drilled the 18 mm hole first then used one of the grommets to aid in centring the holes for the shaft.
Step 17: Cutting Out Your Pick Guard
There is quite a variety of pick guard material available. I have here 3 ply White black white, pearlised white, black white and black white black.
Because the pick guards have a protective film on them I like to mark the back covering them with masking tape to see what I am doing and avoid taking the protective film off by accident. There was also a bit of fiddling with the knob positions. Peeling the protective film off is a special pleasure I reserve for the person receiving the uke.
Also attached is a pdf of the final pick guard template I made for this build.
Step 18: Electrics
These are all the electrics I am putting in and an alternate single unit component that I am not using in this build but could simplify yours if you feel so inclined.
In order of appearance they show
The 9 volt battery case
The socket to plug the instrument into your amplifier. This is a hot tip plug so it only has current when it is plugged in (Plug in battery go flat. Plug out battery stay alive!). I heard one person added a power switch so they could leave their bass plugged in between sets without the battery going flat on them.
The two tone potentiometers.
The volume and switching potentiometers. Because I only have one pickup I removed that switching potentiometers and replaced it with a 2.5 mm socket for the piezo rod to plug into. The socket I used is an earphone socket made to disconnect speakers when the headphone is plugged in and had an issue sorting out which terminal to solder to as they were not labelled so I guessed wrong the first time and had to redo it.
The piezo rod pickup and matching socket are soldered on in the next picture.
The last picture is of a sealed complete unit which is simpler to handle. This one is a passive unit you can get a huge variety of different styles.
Step 19: Fretting
Start by cross checking the fretboard is flat. I had a bit of a visual problem with the area around the fret dots being superglue soaked and shinier than the surrounding wood so I went back over the entire fretboard with a single coat of superglue.
For this build I decided to experiment with a pre-fitting fret technique. Starting at the wide end, frets are cut and their ends are rounded over using a file and then smoothed with super fine sandpaper into perfect semi -hemispherical finished ends that are just shy of the edge of the fretboard. If perchance your fret is accidentally cut too long it can be trimmed. If too short, because of the taper, it can be used further up the fretboard (thanks for the tip Sven). I cut and finished and installed each fret one at a time rather than cut them all and finish them all and then attach them all.
Previously I have just cut the frets a touch long as I installed them and then filed everything flat with a 30 to 40 degree bevelled edge and then smoothed with 400 grit sandpaper rubbed on everything. A lot quicker doing it that way.
My one other issue is that these frets have a slightly longer tang than the narrower uke ones I normally use for building ukes so I had to cut some slots deeper. I stuffed up a few and had to remove the fret using a small chisel to lever them up.
I cross check flatness as much as possible and hammer down or remount high frets (see above) then flatten properly with a diamond sharpening plate.
Step 20: Holes for the Volume and Tone Potentiometers.
First up I put in the battery compartment. No biggie.
Then I carefully drilled through from the front through the pick guard where I was mounting my volume/tone potentiometers and plug. The volume/tone potentiometers are slightly longer than the pick guard and can use a bit of the wood in the body to stabilise them and so that when the knob is fitted it does not stick out too far. The socket unfortunately had to be drilled out because it was a bit short on mounting screw length. The step drill allowed me to bore out to the diameter I needed concentrically from the mounting hole in the pick guard tail. I then followed this up with a 14 mm forstner bit. I could have just filed it out with a rasp and it is not that critical it should be exactly 14 and would not hurt if it were a bit bigger as long as that 14 mm centred hole area was clear.
I also needed a small amount of extra space for the pre-amp unit box. As you may see later the hole I made came perilously close to the rebate for the string mounts so when making yours cross check how they interact before you make the same close to mistake I did.
Step 21: Bridge and Pickup Holes
The bridge was initially shaped at around 100mm wide and 25mm deep and 19mm high.
A slot is cut for the saddle and pickup using a 3.2 mm mini router bit mounted in a drill press. A hole is drilled in the bridge down 4mm in diameter and then in the bottom and in the face of the ukulele a wider hole is made. These holes are larger than the cable to allow movement so that the bridge can be adjusted for intonation. The location of the hole in the top is made where the alignment of the strings and the length of the scale, 485 mm plus a 10mm adjustment for intonation. Intonation adjustment is required because the tuning of the strings reacts to the stress of bending the string down to the fretboard.
Step 22: String Holes
For this design I am adding string holes 25 mm from the theoretical scale length plus the 10 mm theoretical adjustment for intonation. I centred these on the actual centre line of the actual fretboard not on where I thought the centre line was going to be in my initial design. I do this by using a straight edge against either side of the fretboard to project a line to the bridge position and mark the centre point of those two lines,
I want the strings to span from outside to outside about 60 mm as the saddle is 75 mm wide. The strings are 5.0, 4.4, 3.1 and 2.6 mm in diameter. This adds up to 15.1 mm. Because I want equal gaps between the strings the gaps need to be 60 mm -15.1 mm = 44.9 mm divided by 3 = 14.97 mm. Because I know I am not that accurate in my pencil lines I will put them at around 15 mm apart. To do this I measure 30 mm out from the fretboard centre line and mark the width of each string, 15 mm and the width of the next string and so on. If my measurements are spot on, I find that last line is 30 mm from the centre line as well. If it hadn't been then I would have made a mistake somewhere and need to check where I had gone wrong.
I then mark the centre of each of those width of string lines which is where I drill my holes. The drill bits have been chosen to match the string as closely as possible while not being too small. My kit has 5, 4.5, 3,5 and 3 mm bits which makes the strings slide smoothly and yet snug.
I also recessed the back of the body so the strings would not dig into the player's body.
I also added a slight turning ramp next to the holes so they will go round the hole and not have a sharp kink which could lead to breakages.
Step 23: Varnishing and Adding Logos
I covered the fretboard face with masking tape because we are going to be oiling that later.
My first spray coat of varnish is a rough spit coat which really serves to seal things a bit and create a level we can sand down to. Now we sand everything down till there is no more shine. This ensures everything is flat and has been sanded.
Now I add the embedded art and logo. I decided to add my business card to the back as a makers mark. I print onto tracing paper (not baking paper) as it is more permeable and after being embedded in varnish is almost as transparent as water transfer or specialised sticker material and much cheaper. I have simply laid these ones onto a bed of wet varnish and sprayed another layer of varnish over the top. It also works quite well by laying it in superglue. The tracing paper is also quite useful for tracing patterns and I used it for tracing the pick guards as well.
Two or three or four more coats of varnish and sanding between coats. Needless to say feel free to paint the body with whatever lurid tone you fancy. Varnish is just what I used.
Step 24: Putting Grooves in the Nut.
As with the hole drilling for the strings we are attempting to put the strings at even spacing between the strings. First step is to mark the outer edges of the string paths we want. in this case it is simply about 2 to 3 mm in from the edge. These finished up around 39 mm apart. Now comes the maths. Subtract 15.1 (the combined widths of all the strings) this gives us 23.9 mm. Divide by three gives us three 7.97 mm gaps needed. Mark out 5.0 then 8 then 4.4 then 8 then 3.1 then 8 then 2.6 and you reach 39 or there about.
To start the grooves I like to put in a centre starting line with my mini hack saw. The depth of the grooves needs to be close to but not less than the height of the frets. To achieve this I use a piece of metal slightly higher than my frets as a depth stop. in this case it is an old jigsaw blade with a bit of masking tape under it to give it a bit more height. I then get stuck into the task using a few needle files and some rotary tool bits that I had in 2, 3 and 4 mm diameters. We want the grooves to match the diameter of the strings and to ramp slightly down towards the headstock. I used a nifty little rotary tool I just bought to do the majority of the cutting in and finished with a few strokes to widen some of the grooves a little and bring them closer down to the height of the depth stop.
Because I am just in the middle stages of the build I like to keep the depth guide slightly high so I can spend some time later fettling these settings and getting them perfect.
Step 25: Oiling the Fretboard
I use a product called hard burnishing oil to oil the fretboard, though you should be able to get good results with any danish oil, boiled linseed oil or something similar. Varnishing fretboards is not recommended due to chipping and wear and other issues. I decant a small amount of the oil into a tiny plastic bottle which allows me to limit the amount of oil I dab out. I just fold down a 50 mm or so square of paper towel or rag over the mouth of the small bottle turn it upside down for a second and then wipe the wet square over the fretboard.
I leave it to sit for a bit then I rub it down with a paper towel or rag. Two or three applications, rubbing with fine steel wool between coats, is all it needs.
Step 26: Back Cover Plate
Now almost everything is added we can make a cover plate to keep it all concealed. Masking tape is used to create an outline of the hole we have to cover and positions for holes also should be marked now. This is removed and put on cardboard. My first feeble attempt without marking the holes beforehand left a 10 mm border and I got a nasty surprise when I looked at where the screws would go as screw holes 10 mm in from the edge of the cover caught the edge of the hole. A 20 mm overlap allowance and putting the screws 10 mm in from the edge of the cover made things work much better. If you look carefully I crossed out one of my hole positions as it was perilously close to my channel to the battery compartment when I looked closer.
I made my cover out of black white black pick guard material. As with the pick guard I mark the back after covering it with masking tape, cut it out and flip it to reveal the final product and file a 45 degree bevel into the edge. If you want to be fancy you can make it out of matching wood or stainless steel or anything else that takes your fancy.
Step 27: Adding the Electrics.
Starting in no particular order the 9 volt battery lead is fed through to the battery compartment hole. The volume potentiometer is bolted in place at the top end of the knob tail. The two tone potentiometers are stared at and due to no idea as to which one is more treble and which is more bass are put in as they appear to go in best next down the line of the tail. In the end I appear to have the treble first and bass second. Lastly the guitar lead socket gets bolted in.
Knobs are slid into place on the top. as you may be able to see from the side angle the extra few millimetres of wood thickness I left in the top causes the knobs to be more flush with the surface.
Step 28: Add Tuning Pegs
Add the tuning pegs. Grommets first and tuners second. Because I was slightly inaccurate with either in drilling or measuring I had to file a half a millimetre off one of the backing plates of the tuning pegs to make them fit. I tested out the alignment with a single screw in each tuner and had enough wiggle room to straighten them up slightly better before adding the rest of the screw holes and tightening it all down. Make sure they are properly lubricated with a light grease or oil.
Somewhere around this time I added the strap buttons. Not a huge step. One at the centre at the base and one at the tip of the upper horn of the body. Because the body is a little short I would be tempted to use a string above the nut rather than the strap button on the horn. Somewhat handily the strap button makes standing the bass uke on its end leaning against the wall a lot more stable.
Step 29: Add the Bridge and Saddle
The bridge was originally shaped at around 100 mm wide and 25 mm deep and 19 mm high. To work out if this is the correct measurement we need to a investigate the action at the 12th fret. The bass ukulele has a high action compared to other musical instruments where I would normally make a ukulele with the strings seldom more than 3 mm above the frets the bass ukulele has an action about 6 mm above the frets. This is measured in initial setup by placing a straight edge across the bridge up to the first fret, primarily because we have not set up the nut action yet and it gives more consistent results. The first measurements showed I had an action of about 8 or 9 mm at the 12th fret this meant I had to remove a lot of material from the bottom of the bridge to bring that down to something we can work with. I finished up with the bridge being a touch over 12 mm high and the saddle which sits on top of the pickup is about 3 mm higher than that. This gave me an action of around 6 mm at the 12th fret. You will almost certainly have to adjust these measurements yourself. I also introduced a curve in the top of the saddle to match the radius in the fret board and cut it to length to match the 75 mm slot in the bridge.
A length of whipper snipper line was also used to further test and adjust the setup.
Step 30: Adjust the Nut a Little More
I went through my collection of rotary tool bits and picked out the ones that most closely matched my string sizes. These were used to smooth out the string notches I made in the earlier step. To fast forward things I used the whipper snipper line as a temporary guide. The old timey luthiers used to hold down the string between the second and third fret and measure the gap between the string and the first fret. If this was about the thickness of a cigarette paper you were in an ideal position. This technique works for pretty much all fretted instruments from ukes to banjos.
Step 31: String It Up
One end of the string has a stopper or figure 8 knot tied onto it. This is a far more effective stopping knot than a simple overhand knot though in a pinch the simple or overhand knot will suffice. To minimise the amount of winding the strings are stretched a little bit by hand as you slot them into the tuning pegs. Ideally you want about one wind around the post before you get in tune.
Unfortunately the E string popped out of its nut slot during playing, which is not what I was expecting. There are two possible solutions:
- a higher nut with a deeper string groove to make it harder for the string to pop out or
- string trees.
Step 32: Adding String Trees
These are standard fender style bass string trees. Their purpose is to hold the strings down between the tuner and the nut to stop the string from popping out. In this case the E string was the most problematic but the usual position for the string tree on a Fender style bass is between the D and G strings so I added one there too to make things look more traditional even if I didn't need it. I also dremelled out the slightly small string notches in the bottom of the string tree to accommodate the fatter strings of the bass uke a little. A couple of small washers under the string tree were also needed as these strings are a lot fatter than standard bass strings and the deviation introduced looked a little much without them.
The Rodmaster bass needed the string tree on the D and G string as it has a more traditional Fender layout to the head angle. As you can see I made that one myself out of wood.
Step 33: Adjust Intonation
Because we have a floating bridge (i.e. it is not stuck down) we can make some adjustment to the position of the bridge. The reason we need to do this is that when the strings are bent to bring them into contact with the frets there is a bit of extra stress placed on the string so the note is higher than it would be in theory if we shortened the string by the distance between the frets. The manual adjustment is traditionally done at the 12th fret (the theoretical half way mark). If the bridge and nut were equidistant from the 12th fret then the note played on the 12th fret would be slightly higher than the octave above the open string note.
If the note played at the 12th fret is too high the bridge needs to moved away from the 12th fret. If it is too low then the bridge needs to moved towards the 12th fret. Unfortunately it is really tricky to fret these fat strings cleanly each time and together with the height of the action I found it really difficult to get clean consistent results but in the end I prevailed and the intonation adjustment came out at about 11 mm rather than the 10 mm I had initially put in based on my reading of the internet sources.
Step 34: Playing It
As can be expected the the solid body and low tension strings make for a very quiet acoustic playing experience. Plugging it in however makes for a full and deep sound. Even with the high feeling 6 mm action at the 12th fret it is still prone to fret noise when played aggressively. I have decided to christen the noise fret growl instead and make a feature of it.
Step 35: Supplementary Step - Buying a Case.
Because instruments this size are currently a bit of a rarity there is no real market for after market hard cases. However 'student' half size and three quarter size guitars are about the same dimensions and soft cases are available. I brought the bass into my local music store (Better Music in Canberra, Australia-link below) and they had a selection of cases and gig bags and this one fitted the Jaimemaster perfectly. This bag is designed for a half size student classical guitar and is padded all round. Needless to say your measurements and other manufacturer's gig bags may vary so try them out if you can and otherwise measure and check specifications carefully. The fact that it has a full zippered opening is also something to look for as having to push the bass uke down into a bag that only opens in one end could easily disturb the tuners.
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