Solid Body Electric Ukulele - the UkuLiLi

[Chad Schmidt]

My four year old daughter likes to play trains while I play guitar. One day she told me she wishes that the two of us could play guitar together while Mommy plays trains. So I set out to build her an electric ukulele modeled after one of my favorite vintage guitars: the Harmony H44. Since her name is Lillian, I've been calling the instrument the UkuLili.

Here's the original build plan/full scale drawing I made to get started. I chose to make this a concert sized ukulele with a 14.75" scale length.

From what I can tell, original Harmony H44's were constructed with a maple through-neck and poplar body wings so I chose the same woods. There is no angle on the neck relative to the body. I also added a poplar headstock plate. For the fingerboard and bridge I used some Amazon rosewood. Here are the starting materials.

[Chad Schmidt]

I started out by making the fingerboard. First I jointed one face and one edge and used the drum sander to reduce the thickness to a little over 0.25". I use a cross-cut sled on my table saw along with the StewMac blade to cut the fret slots.

I have access to an EDM and CAM software and thought this might be a good project to learn how to use them. I decided to make my own fret scale template. If you look closely you'll see that I'm not a great machinist, but the template worked well.

I did not plan on a truss rod, though since I was using steel strings, I was a little concerned about neck strength. I decided that I would use a carbon fiber tube to provide some additional support to the neck. I partially recessed the tube in the bottom of the fingerboard. Here's my setup on the router table including stop blocks to set the length of the channel and a 0.25" diameter ball router bit. I only cut the channel about 0.040" deep.

[Chad Schmidt]

With fret slots cut and carbon fiber rod channel routed, the next step was to cut the fingerboard to shape. I used a template made of MDF and a pattern bit on my router table for this operation. The template width is undersized so that after the addition of some 0.040" binding the fingerboard width at the nut will be about 1.44" and the width at the 12th fret will be about 1.55".

On the template, you can see a couple holes for pins. The holes are 3/16" diameter and are used to locate the various templates used throughout the construction of the neck. Using wooden dowels in addition to double-sided tape gives me confidence that the templates are not likely to move during routing.

After tapering the fingerboard width I inlayed some 1/4" diameter MOP dots. I made a mistake here and used 1/4" dots when I meant to use 0.16" (4mm) dots. As it turns out, I screwed up this fingerboard and had to redo it (more on this to come). When I remade the fingerboard I did inlay 0.16" dots. I set the MOP into the fingerboard with StewMac black epoxy.

[Dan Smith]

Chad,
That's gonna be a cool youth-sized instrument.
I like it!
Dan

[Chad Schmidt]

Next step was to sand the inlay flush to the fingerboard surface and sand in the fingerboard radius. I went with a 9.5" radius on the fingerboard. I don't have a photo but I like to clamp the sanding beam to my bench and slide the fingerboard, rather then the other way around. For me it seems I'm less prone to having reduced thickness at the nut and body ends of the fingerboard with this process. At this point, the maximum fingerboard thickness is still a little over 0.25". I'll take it down to final thickness after the binding is added.

After cleaning out the fret slots and cutting them to final depth, it was time to install the binding. This the first fingerboard binding job that I've done and I had a really hard time getting a good bond between the 0.040" think ivoroid binding and the wood. In fact, this is where I messed up the first fingerboard. I started off with the Weld-On #16 (I think this is what StewMac recommends) and the binding easily popped off while I was scraping it flush. I scraped the glue off the wood and tried again with the same results. At this point I set up an experiment using Weld-On #16, Duco cement, StewMac epoxy, StewMac medium CA and acetone/wood glue. From these tests, it seemed that CA worked the best. However, the binding detached from the fingerboard again while scraping. At this point the fret slots and fingerboard surfaces were gunked up with CA and I didn't have any more scrap to test on so I decided to dedicate this fingerboard to further testing and start fresh with a new fingerboard.

This is getting to be a long tale so I'll just say that eventually I happened upon the LMI site that recommended Weld-On #4784 and that gave me a good bond. I scraped the binding and finished sanding the radius.

Fret slots are cleaned out and side dot markers were glued in place.

Lastly, fret wire was bent to approximate radius, cut to length, ends were nipped and frets were pressed into place. I used StewMac Narrow/Medium fret wire for this. Fret ends were beveled at 45 degrees.

[Chad Schmidt]

With the fingerboard complete, it's time to turn my attention to the through-neck blank. In actuality, a lot of these things were being done in parallel but it probably tells a better story this way...

Anyway, I started by squaring up the maple neck blank and cutting the angle for the headstock. I went with a 14 degree headstock angle. First I removed the bulk of material with the bandsaw and then used a sanding ramp/sled to finish the face of the headstock. You can see the sled on the back of the bench.

Next I glued on a piece of 1/16" thick poplar headstock veneer. I used the sanding ramp/sled to bevel the edge that contacts the nut at a 14 degree angle. I put in some dowels to keep it from sliding around during gluing so my beveled surface remains perpendicular to the centerline. If you look closely, you can also see the side profile that I marked on prior to starting all this.

After the headstock was glued, I used the router table to cut the slot for the carbon fiber rod. In hindsight I should have done this prior to glueing the headstock veneer. Because I didn't, I needed to prop the neck blank up on some small blocks to clear the headstock veneer.

The carbon fiber rod is from LMI and measures in at slightly greater than 0.25" in diameter. Rather than trying to cut my slot slightly wider than the 0.25" diameter router bit, I chose to chuck the rod into my drill press and using some sand paper, bring the diameter down until it was less than 0.25" and fit in the slot. The rod sits slightly proud of the neck surface so that it mates properly with the fingerboard recess.

[Chad Schmidt]

Chad,
That's gonna be a cool youth-sized instrument.
I like it!
Dan

Thanks Dan, it's nearly done and it turns out that it's a pretty cool adult sized instrument too!

[Chad Schmidt]

Still working on the neck... Next I cut out the headstock shape. I made the template on a CNC mill that I'm also trying to learn how to use effectively. I taped the template in place and drilled the 1/4" holes for the tuning machines. I like to drill the tuner holes before thicknessing the headstock to avoid any tearout. I put 1/4" dowels in a couple of the tuner holes to keep the template from slipping. I also used my sanding ramp with a board screwed to the angled portion so that my headstock face is perpendicular to my drill axis.

Instead of using the router table for this, I decided to try a technique that was posted on the LMI site as one of their informational videos. In a nutshell, I made a cutter by grinding an angle into the non-drill end of a 4mm drill bit. The shank of the bit rides against the template. I ran the drill at about 2000 RPM for this operation. Advantages of this method are that it seems really unlikely that you will get tear-out and you can also get into smaller corners than with a commonly available pattern router bit. Disadvantages of this method are that the chips don't clear so you need to clear them after each pass and sometimes within a pass to avoid burning and this method also takes longer than a router since you can't take very deep depth cuts (I took about 0.1" off in each pass). Overall, I thought the advantages outweigh the disadvantages for me.

To finish the headstock, I used the bandsaw to cut away the excess and then used the sanding ramp with the router to thickness the headstock. I don't have a photo of this last operation but, in a nutshell, the neck blank can be oriented in the sanding ramp so that the angle of the ramp aligns with the required angle on the back of the headstock. I then used the router from my router table with the plate attached (see next photo as an example) to mill the headstock down to final thickness.

I also needed to cut the neck thickness taper at this time. To do this, I used some rails and my router with the table plate attached to cut the thickness. You can't see it in the photo, but the nut end of the neck blank is propped up with the correct diameter drill bit to give the correct angle for the thickness taper I wanted. You can see that I left some material at the neck-to-headstock interface; I thought I'd try carving a volute for the first time.

[Dan Smith]

Very cool!
I like your angle sanding jig.
I'm trying to use mostly hand-cutting tools, but I need lots of practice.
The binding looks great. I did my first using wood binding, it was a real pain.
Best of luck with the NC tool, I've seen some incredible NC work.
Dan

[Chad Schmidt]

Back to work... After cutting the neck thickness taper I chose to drill the jack plug hole while the neck blank still has square sides. I used a 5/8" drill bit, a vertical drilling jig and a drill template for this operation. I need to drill deep enough to penetrate into where the electronics cavity will be; you can see the outline in the photo.

I made the drill template so that I could get all of the tailpiece holes, the jack plug hole and an LED access hole all lined up. I will be using a Fishman Switchjack End Pin Jack to save space in the electronics cavity, though I won't be taking advantage of the switching capability.

You can also see in the photo the two holes that will be used to align and position the neck width taper jig and the fingerboard.

[Chad Schmidt]

One more neck construction post before moving on to the body... I started by using a template to route the neck width taper. The neck width is tapered all the way through the body. To make the template, I started by using my table saw to cut a long piece of MDF with the same taper as the fingerboard. Next I took the completed, bound fingerboard and positioned it on the tapered MDF so the edges were aligned; I marked the nut location. Lastly, I took the fingerboard template shown in post # 3, aligned the centerline of the tapered MDF with the centerline of the fingerboard template and also aligned the fingerboard template with the marked nut location on the MDF; I was now able to drill the locating holes. This process keeps everything aligned and positioned so that when I get to gluing the fingerboard, I know the neck and fingerboard taper will match perfectly. Here's a photo of the completed template with alignment pins.

Here's a photo of a small drill guide for locating the tuning machine holes. The 1/4" diameter holes were drilled earlier using the headstock template. I use a 1/4" pin to locate the drill guide. I will be using Grover Ukulele Tuning Machines. You can also see the extra material that will be shaped into a dart type volute.

[Dan Smith]

Great stuff, Chad!
Thanks for the pix!
Dan

[Chad Schmidt]

Thanks for the pix!

No sweat! Thanks for the interest, keeps me motivated to continue posting. On to the body...

The body is started by first bandsawing to rough shape and then routing to final shape with a template. You can see the template on the router table in the back of the photo. The top and bottom edges were also rounded over while the body was still whole; 1/4" round over on the bottom, 1/8" on the top.

After the body shape was finished there were a few steps to get ready for gluing on the wings:
1. The neck width taper was scribed onto the body to indicate where the wings needed to be cut to join to the neck blank.
2. The body was sawed in half along the center line.
3. 1/4" diameter holes were drilled into the body along this centerline to be used for alignment dowels when gluing. This will be visible in the next post.
4. The two body halves were cut along the scribed lines step 1. so they joint the neck blank at the proper taper. I used a taper sled on the table saw for this cut.

[Chad Schmidt]

With the body wings prepared, the next step was to glue them to the neck. I did one side at a time. The photo shows the 1/4" diameter holes used for alignment. There are corresponding holes in the neck blank that are not visible.

And side two. Starting to look like a guitar - er, Ukulele - now!

[Chad Schmidt]

Clearing out the control cavity is next. It's a pretty large control cavity since it will be enclosing an onboard headphone amplifier circuit with 9-volt battery. The cavity is first hogged out with a Forstner bit.

The control cavity is routed to final shape with a template prepared with a CNC mill. The template is anchored using the pick guard screw holes.

[Chad Schmidt]

Here's a photo of the tuner holes being drilled out to accommodate the tuner bushings. I used the same sanding sled rails that was used earlier to establish the headstock angle. When I built the sanding sled I saved the cutoffs from the rails. I used these cutoffs to wedge under the headstock for support when drilling the bushing holes.

That completes the woodworking aspects of this project that I documented/photographed. There are a few process steps that I don't have photos of:
- The fingerboard was glued to the neck with epoxy
- A hole was drilled for a strap button
- The neck was carved to a C-shape. I used a faceting approach to carve the neck.
- A dart type volute was carved. I wish I had taken process photos of this. It seems I don't even have a photo of the finished dart. I'll make sure I get a shot of it when I'm done with the finishing.

[Chad Schmidt]

So the woodworking aspects of this project were pretty typical. Now I'll get into the unique aspects of the project, the pickup, the hardware and the headphone amplifier. Let's start with the pickup...

This is my first try at making a pickup so I decided to copy as much as possible from a known design. I chose to make a single coil based on dimensions I could find for a Telecaster neck pickup. Here are the drawings I came up with for the flatwork. Dimensions are all in inches.

UkuLiLi Single Coil Pickup.jpg (15.15 KiB) Viewed 23478 times

UkuLiLi Single Coil Pickup_02.jpg (12.59 KiB) Viewed 23478 times

The top flatwork is for the most part the same as the bottom flatwork but with an overall length of 1.791 inches and width of 0.492 inches. I made some MDF templates for both the top and bottom flatwork and used a small parts sled on the router table to trim the flatwork to shape. The top flatwork is 0.062 inches thick and the bottom is 0.094 inches thick.

The bobbin was assembled with Alnico 5 magnets, 0.630 inches tall. Brass eyelets were also installed for the coil ends and connection wire.

[Chad Schmidt]

Since this was my first home made pickup, and I don't anticipate making a lot of my own pickups, I opted to make a pickup winder rather than purchase one of the commercially available winders. The winder was cobbled together with parts from Mouser, Amazon and McMaster-Carr. It's a pretty standard design; the internals are shown in the following photo.

The winder is powered by a 12VDC signal. The speed can be controlled with a potentiometer connected to the PWM controller. The polarity of the DC can reversed so the bobbin can be spun clockwise or counterclockwise. The LED display/counter uses a Reed switch to detect number of rotations. The motor spins at a maximum 500 RPM.

Next is a photo of the bobbin mount and Reed switch magnets. The screw at the top is for attaching to the motor shaft. The two holes at the bottom of the mount provide clearance for the bobbin brass eyelets. Double stick tape is used to attach the bobbin to the mount.

I like bright, shiny lights so I added a lot of them. The wire guide is removable for more compact storage.

Lastly, here's a photo of the overall assembly with a bobbin mounted and the wire guide in place. To control wire tension I used a piece of felt sandwiched in a C-clamp with the wire running through the felt. With this configuration it took about 20 minutes to wind the pickup; I need to switch out the motor for something faster now that I know what to expect.

Final specifications on the pickup: enamel coated wire 43 AWG, 7500 turns, resistance of 5.22 k-ohms, wound CCW when viewed from the top.

[Dan Smith]

Dang!
Your winder looks great!
I always wondered how to accurately attach body wings, thanks for the tips.
I sure like your use of jigs and templates.
I'm finishing a Tele that I made mainly with hand tools.
I spent half a day just getting the neck and pocket whittled out.
I've started another today, I think I'll use the templates I made a few years ago.
I just need to get over the fear of using one of my routers.
Looking good!
Dan

[Gordon Bellerose]

That is a pretty cool little uke!
I also like your home built winder.
Some good stuff in this thread, all the way through. Good job!