My first CBU

UncleElvis

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So, I've been messing around with the idea of building a cigar-box ukulele for a long time now. It's the reason I got into the ukulele in the first place.
Much as I love the instrument, it IS pretty silly and I love the ridiculousness of such a silly instrument sounding so good.

A few weeks ago, I was at the local cigar shop and the owner quite happily passed on an all wood (laminate, sadly) Partagas box (the nice thing about living outside the states... you can get Cubans here!).

Not ready to make my own neck, fretboard, etc., I bought a cheap $42 Chinese jobbie and chopped the neck off.

I wanted to make it even more ridiculous (and cool), so I got some inlay laminate stuff from InlayUSA.com (the super thin stuff) and designed the "Sacre Coeur Tattoo" soundhole.
The Crown of Thorns is Abalone, just stuck directly on the wood, then sanded down. It's not flush, but it's close. The flames are Mother of Pearl and ARE inlaid (went a bit too deep on the body, but it's ok). A note or two to those that are thinking about the InlayUSA stuff.
a) DO put painters tape (the blue stuff worked quite well) on top and maybe even on the bottom, while cutting.
b) Stick it down (I just put the painters tape over it to hold it down) to a hard surface. The Crown of thorns was cut on cardboard and did crack along the edges. Even the Mother of Pearl chipped on the edges, but I think that was more about the seams of the inlay and the intricacy of the points of the flames than anything else.
c) Go slow. REAL slow. I used an xacto knife to cut it and, in my impatience, went too fast, which also caused some jagged edges. The more intricate stuff, I did 5, 6, sometimes 10 passes with the knife, and it gave a MUCH smoother edge.
d) DO rout out the space, even if it's just a little. On a practice piece, I traced around the inlay with the xacto knife (a #1, by the way. Nice small point), then deepened the lines. On a whim, I sort of whittled the inside, just to the lines, so the edges of the inlay would be flush.
It wasn't perfect, but a couple of layers of sealer, sanding with 250 then 500 between, then, of course, going over with steel wool, to buff out the little scratches, and it's close enough that it's barely noticeable when you run your finger over it.
e) yeah, it's $15 or so per sheet, but DO order more than you intend to use. I had planned to fake up purfling on the edges in Abalone (there was a strip of the laminate that had come off, so I said bugger it and routed out the edges), but had run out. My brain and back are thankful for this, but I think it would have looked amazing.

As for the actual box? Seal seal seal seal and sand sand sand sand.

I still have to do the final polish and stuff on it, but my final sand on the top, I went down to bare wood. When I sealed it again, it went on SO smooth, with no grain, no nothing. I polished a little bit of it with some wax and it gleamed like glass.
It also hardened the wood quite nicely, so I don't get dings in it at all.

Ukulele1.jpg

Ukulele2.jpg


I love it, even though it didn't come out exactly how I expected it to.

But it WAS an amazing experience and I learned TONNES.

Big thanks to Pete Howlett, and the rest of you crazy folks, for just being there and doing it.
I would never have had the confidence to attempt this if not for you guys just... well... doing it.
Pete, especially, helped, just for having the videos. I'm not sure how much of what I learned from him was used in this, but I REALLY got an overview into where my head should be at for this project.

The next one is going to be MENTAL! *grin*




Now I just gotta learn how to play the darn thing!
I'm getting there, but still... not terribly good.
 
I love the inlay - very nice instrument! Would be great to hear what it sounds like.
 
LOL

Like I said, Need to learn to play properly! *grin*

I'll see if I can do a vid soon. The strings are still settling in and won't hold tune for very long yet.

What I HAVE played on it, it's a little quiet and muffled, but quite nice. For me, anyway.
The good part of that is that I should be able to play it at night without disturbing the bride.

Strumming with my thumb has a nice soft sound... a little tentative, but pleasant.
With the finger, it's, of course, a little brighter, but still muted.
I've got to redo the bridge, as it's from the crappy uke I bought and it's a one piece wood thing.
I'm gonna carve another and put in a bone bridge... and maybe a pickup.
 
Thank you, sah!

It FINALLY holds tune... more or less... I think it's more that the strings are slackening at the same rate, so they're in tune relative to each other! *lol*... so I was playing it tonight.

I DEFINITELY need to redo the bridge. It's REALLY high. I think it's the angle of the neck joint, but I think adjusting the bridge will fix that.
It's REALLY quiet, too, which is ok, as I intend on trying a pickup on it... and quiet is good with a wife in the other room!
I'm gonna play with some other options, too... Not sure what, but I'm gonna ask around.

Oh.. durr... I'm an idiot! I could ask here!

Any thoughts on making it a little brighter and louder? Would more holes accomplish that? Will it get louder when I put the sealer the back? i.e. the lid? Would sealing the lid completely help? I kinda like that it still opens, so I'm hoping y'all will say, "Nah... that won't do anything noticeable, so don't worry about it."

Thanks for the help.
 
Sealing the lid could help you with your tuning problems, even after the strings have settled. Adding a bone saddle could brighten it and adding a pickup... well you know. All of these combined might make a world of difference.

That's a really groovy CBU, one of the coolest I've seen.
 
Wow! Thanks for the kind words, Vic! It means a lot!

I'm excited to get to carving the new bridge and saddle now... Hmmm... might go beg the pickup off my friend and do two birds with one stone...

Oooh... note to self... order new strings, too... and...

Ooop.. sorry.. babbling. *grin*

Thanks, all.
 
I agree, it's one of the nicest CBUs I've seen. Your inlay work is fantastic and I really like the corners, too.

Like Vic said, sealing the lid is a good idea to increase the structural stability and also to close the resonator.

Regarding the soundhole, it's hard to say but you could use a helmholtz calculation to figure out the basic soundhole Radius/Diameter for the box and then take the Area for that and compare it with the are of your heart shaped soundhole. If you don't know the area you can count it out by tracing the shape onto graph paper and counting the squares. Then compare the two values - it doesn't look all that far off to me. And remember, even if you found that the hole is smaller that the helmholtz-based value you get, adding another, even smaller hole isn't likely to brighten the sound much, as small holes tend to bring out the bass, not the trebles.
 
Thanks, Erich! My first reaction to your post was... "Huh?", then I read on and said "Hey! More information for me! Stuff I didn't know, but can now research!", so thank you.

The soundhole was "eyed up", based on the whole from a similarly sized ukulele. Made it around the same size, then scaled it up a little bit.

Question, would the shape of the hole be what's making it sound muffled? or would it not affect the sound THAT much?

I'll do what you suggested and see how close to the values they are.

Thanks, all for all the suggestions and kind words.
 
Question, would the shape of the hole be what's making it sound muffled? or would it not affect the sound THAT much?

Did you leave the bottom of the cigar box on and use that for your sound board? That may be your problem right there. Some of us replace the bottom with a bit of spruce or red cedar, which we add braces to, to improve the sound.
 
Here's a quick calculation to determine the theoretical soundhole diameter.

First, calculate the volume of the box - measure and multiply the inside length, width and depth of the box.

Based on the volume, you calculate the spherical radius, that is the radius of a sphere that has the same volume, like so:

R = (V/(4/3*PI))^1/3

SHR = R/4, SHD = R/2

In words: Divide the volume V by (4/3 * PI), then take the cubed root of that value to get the sperical radius R.

OK, now you divide the spherical radius R by 4 to get the soundhole radius SHR or by 2 to get the soundhole diameter SHD.

For example, take a box that measures L = 180 mm x W = 120 mm x D = 40 mm.
The volume V = 864,000 cmm.
The sperical radius according to our calculation is R = 59 mm.
The calculated soundhole radius and diameter are then SHR = 14.75 mm, SHD = 29.5 mm.

Now it's your turn to grab your ruler and your pocket calculator and find out for yourself.

BTW, I don't think your heart shaped soundhole should be a problem - I've seen a lot of CBUs with unconventional soundholes that sounded just fine.
 
Thanks for the formula Erich. Would you compensate one sound hole for the other when doing like an additional side sound port or F holes?
 
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Would you compensate one sound hole for the other when doing like an additional side sound port or F holes?

With multiple soundholes you are distributing the area, which in theory means you make two holes that add up to the total area. Remember area A = R^2 (radius squared). So if you wanted two soundholes of the same size (twice the joy) it would be

R1, R2 = ((R^2)/2)^(1/2)

Square the (calculated) radius to get the area, then divide by two to get half the area, then take the square root to get the radius of each hole (and multiply by 2 to get the diameter, which I didn't show above to avoid another set of brackets).

So much for the calculation, but you have to keep in mind that the helmoltz calculation is based on a range of factors, not just the volume. There's also the length of the resonator - if you've seen a tenor sax you know, that ain't no tweeter - and the size of the soundhole. If you make the soundhole smaller, the tone goes down - we can get that from the calculation of resonator frequency. But if you add another soundhole, does it go back up. In theory no, because you have created multiple resonators in one box. In practice it really depends, but it does make it difficult to calculate - you really have to eyeball it and see what you get, then proceed from there.

In general, smaller soundholes sound deeper and darker, larger soundholes sound higher and brighter, too small sounds trapped and muffled, too large sounds thin and airy.
 
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Well Erich that's an excellent explanation and it's something I'm going to study, thanks for the head start. I can see how this could relate to the tuning of a tongue drum too.

Now I'm gonna sit myself down on the porch and finish this Cohiba.
 
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I certainly did. I saw that folks do that, but, if I'm being honest, was so excited to get to the inlay work that I decided to just go for it.

I'm gonna keep playing with it and see what can do. As it stands now, it doesn't sound horrible (it's WAY fuller than the cheapo I stole the neck off! *lol*), so I'm REALLY happy with the first attempt.

Ok, couple of quickie questions for my next one...

How thick do you think I should do the top, back and sides?

Is 1/8" too thick? I'd be using Bermuda Cedar and my carpenter friends have expressed concern for even that thin, as it's crazy humid here and Bermuda cedar that thin has a nasty tendency to split.

I'm thinking about doing the whole thing in Bermuda cedar: box, neck, etc., but doing it like the stick CB Guitar thingies (You can tell I'm a master luthier by the technical terms I use! *lol*). Any concerns, advice, etc?


On another note, does anyone know the regulations on Cuban cigar BOXES going into the USA?

I may be getting access to a bunch of them and thought I might offer the ones I don't use to you kind folks at UU.
 
Erich! Yer killin' me!

What scares me is that I actually understood most of that! It's been WAY too many years since I did geometry... or math of any sort!

Thanks for the great explanation. I've copied it down into my "Cool stuff I need to know for my new hobby" notebook... so not only does my head hurt, so does my hand! *grin*
 
Erich! Yer killin' me!

What scares me is that I actually understood most of that! It's been WAY too many years since I did geometry... or math of any sort!

Thanks for the great explanation. I've copied it down into my "Cool stuff I need to know for my new hobby" notebook... so not only does my head hurt, so does my hand! *grin*

Right on, math gives me a nosebleed, but it's much needed.
 
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