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Hello,

I spun up a new uke build this weekend. It’s a cocobolo tenor. I thought this would be a good opportunity to do a build thread. I’ve not done one of these so should be educational for me as well. Any feedback on my processes, tooling, etc.... are appreciated. I’ve built a handful of uke’s so far.

This will be a cocobolo B&S with an Adi top I got from LMI on the uke month discount (still going on, btw ). The neck is a CNC’d mahogany neck from our friend Andy Birko. The fretboard is cocobolo as well.

So far I have the top and back joined. The back has the marriage strip installed. The fretboard is slotted and cut to the shape I like to use. I’m going to try to use those two scrap coco pieces for a rosette and soundhole binding. The sides bent for solid lining laminations are paulownia. I put the blocks in this past weekend as well.



















Brad


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Minor progress this evening, only an hour of shop time after work.

- Rough cut and radius the bracing
- Shape the marriage strip with a little sanding caul.
- Flatten the top and mark out the rosette.





Brad

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A little before work shop time this morning.

- Notched in the back braces. For this I like to use a curved veneer saw to cut the initial notches just under sized. I use tape so that when I see the saw start the kiss the top of the tape I stop. The notches are then taken to final width with a chisel.

- Put a pre-scallop taper on the braces. For this I use the drum sander by opening the lid and freehand it a bit. I do mark out the rough taper to make sure I don’t go crazy with it. A bandsaw works good here too of course. I also have used a oscillating sander and the luthiers friend but I didn’t this time.

The braces sit down nicely with just a single go-bar so are good to go. I’ll glue with hide glue after work and start cutting the rosette channel.



















Brad


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Just realized the images were all gigantic in the web view on the PC. Should be fixed now.


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Looks great - keep 'em coming

Ed

Thanks, Ed.

After work progress today.

- Glued the back braces on. I like to use little HDPE strips to create a locator for the brace once it has glue on it. It’s easy enough to bump the gobars over onto the brace. I use hide for top and back braces. Titebond for pretty much everything else except lining and fretboard which get epoxied.

I use a heating blanket to warm up the parts. It’s probably not getting it quite as hot as it should but it’s something.

- Cut the rosette ring and the soundhole binding ring. I will install them tomorrow before work. The last time I inlaid a soundhole binding ring I got the math wrong. Let’s see if I get it right this time.

I really like the Wells Karol jig and especially the battery powered router. Stops on a dime!











Brad


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Some more progress today - things are starting to take shape - or at least be cut to shape.

- Cut the back to shape.

- Cut the rosette and soundhole binding channels. The “soundhole binding” channel gets cut 2.25mm deep. The soundhole binding ring is just a tad over 2.25mm. The idea is to set the ring in and then remove material from the inside the box facing side of the top. The rosette is inlaid as normal. Run the inside the back facing side through the drum sander until today can see the ring. The outcome is the soundhole ring goes all the way through. This is a trick I learned here on the OLF.

- Cut and bent some binding. I’ll use ebony for for this one and bent the binding separate from the lower purfling line. I’ll install the purfling first and then the binding. I like doing it this way when doing end wedge miter.

The little template that shows the Head - Waist - Tail locations for multiple sizes is something I learned here I believe. Can not recall for sure.



Inlay the soundhole binding ring first.


Inlay the rest of the rosette and purfling lines


Flood with CA








Backside, you can see the ring (aka I did the math right this time )


I really need a new blade for my small bandsaw






Brad


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Some progress before work today....

- Took the binding out of the bender only to find that two broke right at the waist. I’ve always bent extras and usually don’t need them. Glad I did it this time.

- Sleepy shop puppy

- Drew out the string paths so I can get started on the bridge this weekend.

- Glue and vacuum the solid lining sides. I use a continuous vac I got from our friend James Orr and I also tried Unibond 800 this time which he recommended. Hopefully I like it because I bought enough to last a while.








Vac form with packing tape so I don’t glue the piece to it.













I try to keep the waist pressed in position while the bag is vacuuming down.





Around 21.5” Hg


Brad


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Minor progress after work. It’s movie night so only an hour in the shop!

- Solid lining side came out fine. A few small gaps but nothing major.

- Glued on the upper transverse brace. It goes on flat and goes on first. I got out the heat lamp tonight!

Marked out the bridge blank and drilled the holes for the string slots. This is a very basic bridge design, I might divert half way through, depends on how I like this string slot idea compared to doing a tie block.

- I’m not sure about the movie. Maybe Trolls 2.







I don’t know why this looks so crazy crooked. It’s definitely not.







Brad


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Planning on low G?? Slanted saddle for compensation makes sense.


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Hi Ed,

Yes, I was planning for a low G on this one but I’m going back and forth on trying to do a straight 1/8” saddle and compensate the saddle itself vs a compensated slot.

Thoughts on this? I kind of like the idea of making two saddles and a straight slot, that way it could be either way.

Edited to add: I just realized the template shows a compensated slot. That’s just the outside shape template I use for both. You can see that it actually has 6 strings. My wife just took the template I use for guitar and shrunk it. She helps me with making the template layout in Adobe illustrator.

Brad


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Good progress today on this and another Ziricote uke I’m building that is much further along.

- Started the day driving the bus.

- Put in the side reinforcement tape. I use black bias tape and hide glue as learned here from several folks. It goes on pretty easy.

- Cut up the remaining braces and glued on the bridge plate. This is the first time I’ve used a hardwood plate on a uke. It’s just a side cut off from a guitar thinned to 1.5mm. It’s glued in with a caul that is 30’ radius but the plate itself is not. I did cut a taper in the sides so that the edge of the plate won’t follow a grain line of the spruce. I watched a YouTube video where Beau Hannam recommended that. Seemed like a good idea.

- I cut the lining side into strips and installed it. The method I use is from Burton LeGeyt and his solid lining tutorial here in the tuts forum. The real genius about this method is putting the taper into the lining so that you don’t have to force it on the back or cut it so that it’s one length and the tail and another at the neck. Using this method you end up with a uniform strip. Rather than me trying to explain it I would recommend reading Burton’s tutorial- viewtopic.php?f=10117&t=21455

- The bridge is shaped and slotted just needs sanding and polishing. I was going to try something new with string slots but diverted back to the tie block which I’ve done in the past. I drilled the string holes on a 5 degree taper but I think I will do 10 next time. It does help to have the holes on an angle when stringing it up. I use the SM slotting jig for both on the body and off the body routing. I modified the plate to take a DeWalt 611.



















Mark the taper on the back:




Sand to the line:


Run it through the bandsaw with the sanded edge facing the fence.


I run them over a round over bit to clean up the inside edge.


You can see how they are tapered.








5 degree angle (10 next time )




Here is my slotting setup for “off-body” cutting of the slots.






Brad



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Good progress today.... I’m slowly starting to work more by feel and intuitively which is good and something I want to continue to focus on. Sometimes I get too fixated on the numbers and plans and books for every little step. Trying to break that habit.

- Initial shaping on the top braces, notch them for the bridge patch and radius the bottom. Check the fit and then glue them on. The notch for the bridge plate is a trick I learned from Pat Foster here on the OLF. Using a proxy bridge plate to set the depth of cut. Works great! http://www.patfosterguitars.com/37hause ... 06833.html

- Shaping and sanding the back braces. Warning - obligatory pics with plane and chisel shavings ahead!!

- Mark and notch the marriage strip and back braces. I use a router to get it close and then files to finish it off.

- Route the end wedge strip. I use the Luthier Tool jig with the classical template which cuts a parallel sided strip.

- Finish sanding of the bridge and polishing with a little wax.



















Mark the marriage strip while the back is clamped to the rims.


Mark the brace locations across the rims.




















Brad


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This is a nice set of build progress photos. Thanks for posting these. I'm looking forward to seeing it when it's complete. The cocobolo looks great and I like the curved design element that's in the fretboard end and on the bridge.

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Got up early for an hour of shop time before work...

- Glued the back on to the rims. I’m using a clamping caul that Colin North recommended here on the OLF. It’s thin hardboard and works great!

In case anyone notices the tape at the end of the go-bars, I made two lengths. One for glueing braces (the normal length that comes from luthier suppliers), and a shorter length. The normal are marked with blue tape and the shorter with green tape. I store them above the gobar deck in PVC tubes. I also put the gobar deck on a lazy suzan which I’ve enjoyed having.

- Initial carving of the top braces. Will finish sanding after work and close the box!













Brad


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Brief update....

- I had to take a step back because the top was doing something odd. I had put the bridge plate on flat instead of radiusing it first which caused the top to distort in a weird way. I normally use spruce for the bridge patch but this time I used rosewood. So, I took the fan braces and bridge plate back off (hooray hide glue) radiused the plate and made a new set of fan braces which are glued up now.

- I also trimmed the back plate flush. Luckily a piece of binding and purfling fits perfectly tight without any glue in the tail wedge slot so that I can run the flush trim bit around it.

Will try to shape the braces and close the box before work tomorrow.









Brad


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Getting back on track, the box is now closed.

- Shape and final sand the bracing and inside face of the top.

- Shave the tail block back to even with the lining. I like to use a microplane for this.

- Mark the upper braces to let them into the lining.

- Close the box.

- Route off the overhang of the top. Will be ready to start binding tomorrow!

















Brad


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Some progress so far today...

- Cutting the binding channels. This is a process that I like to write out the steps I’m going to perform before jumping in. It helps me to think through it and also to avoid mistakes. About a year and a half ago I had a tragic experience with a dred I was working on so I’m more cautious at this stage now.

I don’t think I do anything out of the ordinary in this process. I do take multiple passes stepping the bearing down. I don’t know if this is standard practice or not.

I cut the channels so that the binding and purfling is right at or just a hair below the top and sides. That way I’m bringing the sides down to the binding and not the other way around. This was suggested here on the OLF and I’ve used this method on the last few binding jobs and I like it better. It’s easier to keep the binding uniform.

There was a nik out of the upper bout and I had to deal with that when cutting the channel. I first tried just tape which worked ok but second pass I put a piece of fiber paper to fill the void. It came out better the second time.

Once I’m done I clean up the channels with a sanding stick and spray shellac on them. This is because I use CA to attach the binding and purfling.



Here are pics of my binding carrier. I use the newer LMI tower jig which does a good job. I made this carrier. I like the little Rockler knobs for adjustment.





First I figure out the total depth for the binding and purfling together on a sacrificial board. In this case it was the .680” bearing.





Since the final target is the .680 bearing I chose to step down at 840 -> 780 -> 680.



First pass



This is where the nik in the side caused an issue and how I worked around it.





Testing the back. I flip the body over at each step in order to do both the top and back with the same depth and bearing.





Next pass on the top


The tape alone didn’t work so I added the fiber board.





Looks good now.



The rest is just testing the fit at each step.



Testing the cut on the sacrificial board



I cut the binding channel in just two steps. It’s 840 -> 780 and done.















Clean up the channels with a sanding stick. I take time here especially on the top where the spruce can need a lot of cleaning.





Clean up the end wedge channel.



Spray another coat of shellac to get ready for gluing the purfling next. The rosette looks nice with a little finish on it.



Brad


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Update from today...

- The binding went on what I would call “ok”. There was more scraping and sanding than I expected. I thought I had it dialed in but still it needed a lot of scraping.

The way I have been doing binding is I put the top and back purfling on using a plastic spacer as a proxy for the binding. Then I put the side purfling on in a second step using the same spacer. I put the binding on last. This has advantages and disadvantages. The advantage is that for me there is less chance of messing up the mitre on the end graft when trying to cut a mitre on purfling that is already attached to the binding. The disadvantage is it is more steps and takes a lot longer with all the taping and un-taping.



HDPE strips that are the binding proxy






First purfling attached.




I put an HDPE spacer in the end graft and then mitre the purfling along the channel




Putting the side purfling on requires less tape because it’s just downward pressure.








Both purfling attached




End graft




Binding on




Sanded and scraped back


I put a piece of frisket film on the top to try to protect it from all the cocobolo dust. Maybe a bad idea to leave it on long term, not sure.


Note the finger. Scary sharp indeed.


Brad


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Thanks for this latest post. I see two ideas I may try out next time.

The first has to do with the side purfling. I too install the side purfling separate from the binding and for the same reason that it makes the miters at the end graft easier to do. I like your idea of using the HDPE strips as binding and then taping it down on top of the side purfling when gluing it on. That would be faster than the method I've been using which is to glue the mitered purfling down with CA starting at the end graft and then working my way along the length of the purfling with CA around to the neck end.

The second is that you install the end graft after the side purfling. I've been installing the end graft first and the routing the binding/purfling channel with a small spacer on the top or back at the position of the end graft. The spacer is made from the purfling so the router steps up when passing the end graft by the thickness of the purfling. Your approach would make it even easier to get good miters at the end graft and to get the length of the end graft just right.

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I will put the end graft in a little longer to start. I seem to get good results from then using a safe edge file to bring it back close and then run a chisel flat against the purfling and shave the end graft that last little bit.

Glad you found some of it useful.




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Progress for today....

I’m quitting early, see below.

- Finish sanding and cleaning up the binding on the sides. There was one minor gap that I’ll have to deal with later. Ebony binding makes this easy though. There is still another pass when the final sand before finish happens.

- Cut the mortise and tenon. For this procedure I use the LuthierTool jig which is great. There’s a little bit of a learning curve and it takes some repetition to get comfortable with the sequence. I’ll try to comment below on each step of the procedure in case it helps anyone considering this jig. You’ll see below why it’s a short day. My nerves are fried but it’s not catastrophic at all, I was only doing the first pass on the neck.

- Lastly, a few shots of it cleaned up. It’s starting to look like a thing!

Cleaned up after scraping and sanding. Still a little left to do but that comes later.





For cleaning up the sides I like to use this Abranet set of abrasives and the block. I use it attached to a shop vac.



Next it’s on to routing the mortise and tenon. Here are the templates I need. There is a mortise and tenon plexiglass template. On the right is the centering guide used to center up the edge vise onto the body. There are also wooden templates that I made. The one on the left is just an open template so I can go around with the router and clean up the outsides of the heel after routing. The templates on the top are drilling templates I use to locate the hanger bolt I use to attach the neck. There is also a template for the body side that aligns the hole drilled into the neck block.



I use necks from Andy Birko. This is a 14 fret uke neck I’ll use for this instrument. There is a channel for gluing a carbon fiber rod which I will epoxy in later.



I had to make custom pins that are 1/8” for the alignment of the neck slot. I just used all thread chucked up in the drill press and took a file to it until it was .125”.





First thing to do is zero out the jig. I use a square to square up the table to the bar that holds the dial indicator. This is not totally needed but I do it anyway. I then zero out the jig using a straight board per the instructions from LuthierTool. This sets everything to zero.



Once it is zeroed out I use this patent pending holder to keep the dial plunger out of the way while I take the alignment board out. I got tired or always snaking the indicator and worrying if I knocked it out of whack.





Next I put the edge vise on the body using the centering plexiglass plate and put it onto the jig. I make sure everything is centered and that the dial indicator is at the saddle location.





Next I loosen the side bolts on the table and adjust the tilt until it’s back at zero. Lock everything down and it’s ready to rout.



Now you can see why it’s a short day. On the first pass the template tongue snapped and the router went haywire. I’ve already contacted Chris at LuthierTool to get a new one.



I went ahead and cut the mortise so I’ll now wait for the replacement template. Here are the last few pics.







Brad


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I’m waiting for the new routing template to arrive, but it won’t be here until Friday. As they say, idle hands... so let’s try to find something to move the build forward.

I have had a set of Rubner tuners for a slotted head uke for almost 4 years sitting and waiting. Maybe now is the time.

First, I’ve never used the slot head jig I have for ukes. When I bought it I also bought the uke template. I’ve used it for guitars and it works great, but this will be a first for a uke.

Right out of the gate there is a challenge, the jig has two sets of templates. There is the slot template itself and the tuner hole on the side. The Rubner tuners I have are for uke but the spacing is the same as guitars, whereas the Luthiertool jig has a spacing slightly wider. So I think I will have to do this in a two step process where I drill the tuner holes first then slide the jig down and rout out the slots. That will put the holes centered on the slot.

Time for a test. I made four proxy headstocks that are the same size as the uke headstock. I also made a new shape template that maximizes the size of the headstock real estate. I’ll use these proxy headstocks to experiment.

While I was at it I did a couple different lamination options so I can see them in advance.





Four headstocks and four headplates:


Use the headplates as cauls to glue up the lamination


Slotted head template on the left. Turns out it’s only 5mm or so longer.










I will rout them to shape before work in the morning and rout the test slots.

Here are the tuners:




Brad


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Progress before work this morning...

The space on the headstock is really tight but I think I can make it work. I think I’ll be glad I made the four test headstocks when it’s time to do the real thing.

Rough cut the proxy headstocks with the bandsaw and then rout with the template.











Set the depth stop on the drill bit. The roller for the tuners is 6mm but the jig has 1/4” drill bushings. I’ll try taking up the slack with a wind or two of tape and see how it goes. Roller length is 25mm.





The headstock thickness is 18.5mm and the template centers the bit at 11mm which will not work for these thin headstocks. I’ll have to think about how to handle this but I’m inclined to make a shim that is 1.75mm to push the point of the bit up to 9.25mm on the headstock which is the center of the headstock.





I’m going to use the compact router for this operation. I’m using a 7/16” bushing with a 1/4” bit. The idea is to rout with the bigger bushing, drill the tuner holes, and then rout with the smaller 3/8” bushing as a second pass to clean up the slot. Even though the router doesn’t have a plunge base it’s easy enough to move the bit to the center of the slot when adjusting the depth and then lock it back down.



I put some cork on the hold down to protect the headstock.



Routing the slots.





Makes quite the mess.





So the first test shows I’ll need to slide the slots down further and perhaps scoot the logo up just a bit to maybe 3mm instead of 5mm from the top of the headstock.



I will need to think about just how low, meaning how close to the nut, I can take the slots. Also how wide do they actually have to be? Is this enough or do I really need to step up to the next bushing and make them wider.

More testing tonight after work.

Brad


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After work progress today...

First, I learned from my 12 yr old how to markup images on the iPhone so prepare yourself.

I moved on to the second proxy headstock to try some adjustments. I moved the slots down by 3mm and put a 1mm shim in on each side of the headstock. The goal is to push the slot closer to the edge of the headstock. Basically leaving just enough to get the screws into the tuner without poking through into the slot.

An additional challenge is that the tuner holes aren’t centered on the slots because I have to use the guitar tuner hole template and the ukulele slot template. The reason is that the tuner hole jig for ukulele from Luthiertool is not standard 35mm spacing but the tuners I have are 35mm. To deal with this I put registration lines on the center of the slot and the center of the tuner hole template so that I could drill the holes and then slide the headstock up to rout the slots.

Yet another challenge was that the tuner holes aren’t centered on the headstock so I put a shim in that moved the holes down to align with the center of the headstock. There is so little room for play that I think all of these will matter in order to have a satisfactory result in the end.

Registration marks added to both the slot template and the tuner hole template. These represent the center of each template.



I slid the headstock up to where it needed to go and then marked the registration mark onto the headstock. Then transferred the line around the entire headstock.







Next, put the shim in place and check the hole locations. This worked well.





Line up the registration line and test the alignment. The shim worked!





Drill the holes. The alignment looks good.





Put the 1mm spacer in on each side of the headstock.





Once again line up the registration line.







Everything seems to be aligned.



The 1mm spacer did the trick for making the needed room for the logo.



But!!! Now the roller is not centered!



Also I think lowering the slot down won’t leave me enough room to make the ramps. I have one more option though. The headstock template was 2mm narrower than the actual headstock on the CNC neck. That means I have 2mm I could potentially add back without having to use the shims. I will make one more mock up with the extra 2mm added and see if we have a winner.

Brad


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