Dorm chair mandolele

A while ago I spotted a broken chair in the basement.  I scavenged some oak from it, and finally got around to using it this past weekend.  In a one-night extravaganza of poor craftsmanship, I put this together.

machine tuners

 The uke's tuning pegs are frustratingly coarse when it comes to tuning, so I'm exploring replacing them with machine tuners.  Machine tuners put a reduction drive between the person who's tuning and the instrument, making more turns of the knob equate to a smaller change in pitch.

 I used the lathe to shape some brass into a taper that approximates that of the original tuning peg.  I made the middles thinner to add a bit more mechanical advantage to that reduction drive I was talking about earlier.

 These are the beginnings of the blocks that will hold the worm (screw) against the gear on the tuner.










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Update: 3/16/12

I never actually got around to finishing this for a couple of reasons.
1, I made the machine tuner pegs too short.  They didn't slide all the way into the head of the instrument..

and 2, I got over it.  Wood tuning pegs are more than sufficient for this lightweight uke.  I reshaped the ones that were giving me trouble and applied a bit of resin (epoxy minus hardener) to them.  After the resin dried out a bit, they got good and sticky.  Everything's cool now.

Also, I looked at a real violin up close the other day.  They're beautiful!  A truly fit design.

Tcopter flight testing and more ukulele

After some minor controls hiccups, I got tcopter flying.

Thanks to Annie for filming.

One thing I noticed right away about the flight was that it was less floaty, zippy.  It seemed sluggish compared to beforehand.  Now, the setup is a bit heavier than last time, but only by maybe thirty grams.  Then again, that's about 15% more than last time.  Too bad Newton wouldn't let me get away with that.

Each experience I have like this reminds me to KEEP THINGS LIGHT!  When they're light, they take less force to move, so they can stay in the air longer.  Of course, I could slap on a bigger power system to give it more force to thrash around, but then the frame would have to to be built (heavier) to withstand the extra force.

I'm currently looking into solutions for making a really light frame that can still take some abuse.  One trick that I learned from some friends in DBF was to sandwich end-grain balsa wood between sheets of carbon fiber.  It makes super light (not much heavier than balsa) and very stiff spars.  

first google result for "end grain balsa spar"

After I have some more lab experience, I'd like to try using these as arms.   I bet I could make the whole frame that way.  But for the time being, I might just try balsa arms.  Balsa is pretty brittle on its own, so I'll probably reinforce it with some kind of stiff fiber (thin strips of bamboo?).   Also, I want to keep this project accessible to DIYers without going over the top with high tech materials.

In other news, I've been having a lot of fun with the ukulele (when it's in tune).  The nut is slightly angled, so the distance from it to the first fret is just a bit longer than it should be for the low string.  I made a quick fix by sticking a chunk of bamboo under the string shoved up against the nut.

  I'll rip the nut off and re position it later.
Also, I've noticed that some of the drier days make the pegs shrink and slip.  I can still tune them, it's just a bit more involved than I'd like.  Being that it's IAP, I drew up some plans for machine tuners:

I planned on using a drywall screw as the worm gear, filing off the unnecessary bits of screw.  I was also thinking of cutting the large gear myself.. with a hacksaw.  This will have to wait for another long weekend, because I fear it will take many hours.

Before you tell me that I can buy cheap and much nicer machine heads for a few dollars each, just let me say that my stubbornness to buy as little and make as much as possible for this uke has held strong.

Machine tuners will happen.  

Ukulele (guitar-like thing megapost)

A few days ago, I started building an ukulele.  I've wanted to attempt a stringed instrument for a while, and winter break seemed like a good time to start.  

First, I browsed uke pics to get an idea of the proportions.  I learned from Wikipedia that ukuleles are classified by size.  

Type	Scale length[26]	Total length	Tuning[27]
soprano or standard	13" (33 cm)	21" (53 cm)	A4-D4-F#4-B4 or G4-C4-E4-A4
concert	15" (38 cm)	23" (58 cm)	G4-C4-E4-A4, or G3-C4-E4-A4
tenor	17" (43 cm)	26" (66 cm)	G3-C4-E4-A4, G4-C4-E4-A4 , or D4-G3-B3-E4
baritone	19" (48 cm)	30" (76 cm)	D3-G3-B3-E4

I settled on a tenor because I figured I could get away with larger tolerances, but I still wanted some degree of portability.


Design

I first found some diagrams to get an idea of scale.  A search turned up this diagram of an ukulele neck, and I  used this as a template for mine.  


A great little program called FretFind helped me layout the locations of the frets, as well as sizes of the neck, nut and bridge.








Build 

  I started by carving the neck out of a chunk of tulip poplar.  I made rough cuts with a pruning saw then followed up with a chisel and a gouge.  It's a pretty soft wood with a dead straight grain.


I'm using a machinist's vise.  I duct taped some thin ply scrap to the jaws so it wouldn't mark up the wood

done with the first round of chiseling.  

I wanted to inlay a fretboard, something a bit more durable and nicer looking than the poplar.  To make room for the inlay, I set the blade on the table saw to about 3/16" and took some slices out of the top of the neck. 
After that, it was easy to clean it up and flatten it out with a straight chisel.

glue applied

The fretboard - It's a piece of bloodwood scrap that my Dad had lying around.

The spring clamps weren't as snug as I would've liked, so I later used C clamps instead.

Tuning Pegs

I opted out of using geared tuners since the tension on the strings won't be anywhere near that of a steel string guitar.  Instead, I made wood tuning pegs.  

That's a small piece of white oak that I sloppily cut with a coping saw.  I whittled it down with a knife until it stopped looking so boxy, but it still wasn't round enough.

I hesitate to use the word lathe...

Enter the inverted cordless drill in a vise!

This worked surprisingly well.  I'd put the smallest end of the peg in the chuck, operate the drill with my left hand, and manipulate a chisel with my right.  I don't know the technical name for it, but I used a roller that's supposed to support long pieces of stock as the thing that I rest the chisel on.

 Here's a little test head I made so I wouldn't ruin the real one.  The outer hole is drilled to something like 9/32".  The inner section is first drilled to 1/4", then the opening is expanded just a bit to 17/64".  I can approximate a taper that way.  I used calipers when sanding the peg in my "lathe" to match the taper of the hole.  


The peg is a bit blackened in this photo because I rubbed it in coal dust.  That seems to give it a bit more of a hold.

Back to the neck

I trimmed the excess inlay from the neck with my trusty coping saw.

After some sanding...

With that done, I started shaping the head to accept tuners.  I bored some holes and chiseled the rest.

Box Building

I read somewhere that cedar makes a good soundbox, so I dug through a stack of some old cedar siding that used to be installed on our house until I found some sufficiently not rotten pieces.  

They're about 7/8" thick on one side, then they taper down to 1/4" or less on the bottom.  I wanted the sides of my box to be thin, less than a quarter inch.  I got to work with a plane to get them down to size.

It took a few hours.  If I'd had access to a proper woodshop, I probably could have done it in a few minutes.

Here's the soundboard and the sides.  I made the soundboard thinner than the sides because a thinner membrane generally means brighter sound.

Here's the tail end of the box

more to come..


Update 1/3/12:  It's done as of a few days ago - here are the rest of the build photos:

box!  I glued and tacked it together

A piece of juniper harvested from our woods a few years ago

piece of juniper carved into the nut

first fret!  I used the fret calculator mentioned earlier to position it just right

clamping the bridge to the soundboard.
I could have used about five extra hands while setting this one up.

more frets

flush cut saw used for cutting fret slots

the soundboard was a bit flexy for my liking, so I added some maple bracing on  the back (soon to be inside)

done and strung!  I cut the soundhole by tracing out a circle, then drilling out small holes all along the perimeter.  

linseed oil gives it some character