Next Up: The Curly Twins

saltytri · Aug 12, 2012

Well, fraternal twins but not identical. The next project is a pair of concerts. One is all curly mango and the other is curly bigleaf maple with a European spruce top. Both will get Spanish cedar necks but the other details haven't developed yet. Stay tuned.

The sides were bent on this new bender. It's pretty much conventional. The mold portion is replaceable for different sizes and shapes. The 6" by 24" heat blanket came from McMaster-Carr. Both sides can be bent at once side-by-side. The extra clamps at the bouts may be overkill but the idea is to apply more pressure more evenly to encourage figured wood to bend smoothly, as it has a tendency to kink or break. These don't add much to the cost or complexity and it feels good to have a little extra insurance. The knobs are also from McMaster-Carr. It's handy to be able to spin them in and out quickly. Heat control is courtesy of a twenty buck variable output box from Harbor Freight (I know, I know). It runs through a hardware store timer to back up my natural inclination not to leave hot things running too long. The Fluke thermometer is a luxury but it was already on hand and the accuracy can't hurt.

David Newton · Aug 12, 2012

That is about the nicest set-up for bending I've ever seen. And shiny too!
Oh yeah, nice wood.

saltytri · Aug 12, 2012

It'll look grungy soon enough!

BTW, I love the "Simple Soprano." There is lot to be said for sticking to the basics.

David Newton · Aug 12, 2012

Thank you.
I'm glad there is room at the table for everyone.

Hippie Dribble · Aug 12, 2012

gorgeous looking wood again David. You sure have a keen eye for this stuff. Incredible looking set up, all bases covered. Wow, this thread'll be worth watching...

saltytri · Aug 12, 2012

Jon, I'm just hoping that I don't hear a loud "CRACK" along the way.

808boy · Aug 12, 2012

Aloha David,
Don't know much about Luthurie, but do know mechanics and that bending setup looks great. Nice woods also. That Mango looks like the Edmund Bacani (Nice) mango uke that I have. Nice voice out of it (Concert), deep tones almost like a tenor.
Will be watching your progress.......................BO........................

Pete Howlett · Aug 12, 2012

Great bending set-up - nice and simple and a development I am going to seriously look at. Thanks.

dannyb · Aug 12, 2012

That is really a nice! Your equipment is as nice and clean as your two previously posted ukes. Your mango has nice curl.
As earlier we spoke and mentioned all the learning lessons with each new build. My curly mango build was a learning lesson for me. It is the only one that I had to take the top and laminate it to the back in order to give it some strength. I just sanded a little bit to much and both pieces were wet noodles. Luckily Bob Gleason suggested that I could laminate the two and I did. Put a mohagany top and proceeded with the build. Turned out rather nice I thought. I think that build is on my website: papasukuleles.com. Check it out. Danny B.

saltytri · Aug 12, 2012

Danny:

That's a pretty mango concert.

I've left top and back a bit thick for the time being. You know that thing about how hard it is too add material back? It does seem that this wood doesn't want to be skinny-ed down too much.

Pete Beardsley · Aug 12, 2012

Mmmmm mango! [/Homer Simpson] The Maple also looks absolutely fabulous. Another one of your threads to bookmark methinks!
Thanks for continuing to share your work dude.

luluwrites · Aug 12, 2012

I hope you'll post lots of process pics. They look rather pretty already!

saltytri · Aug 12, 2012

luluwrites said:
I hope you'll post lots of process pics.

Thanks for the interest! Here is a method of making rosettes out of burl. This one started as a thin slice off of a block of camphor burl. The slice was glued onto a scrap of eighth inch plywood and then centered on a rotary table under a high speed motor. The piece that is standing on edge is a similar slice of maple burl that will also be a rosette. The rotary table turns the material under a router bit to cut a perfect circle.

Thin strips of ebony are bent into circle on a hot pipe and then formed to the edges of the burl ring. CA glues them into place. The assembly is then turned against the router bit, resulting in a uniformly wide trim strip of ebony. The top of the rosette is then roughly surfaced with the router bit before being popped off the plywood backing.

I was considering using this rosette on the Mango Twin but after wiping the top with naptha to bring out the grain and color, this doesn't seem like such a good idea. The mango is just too complex - it needs to be the focus, with simpler ornamentation. Maybe a single ring of ebony or mother of pearl?

On the other hand, it looks great sitting on the spruce top and the color complements the curly maple of the other Twin.

saltytri · Aug 13, 2012

OK, lulu, here you go. Here's the process for fitting the tail and heel blocks. In this example, the tail block is already glued in place. The sides are clamped in the mold with the tail seam at the center line. The first side is marked at the heel end so that it can be cut on the center line.

The side is clamped with a piece of wood along the marked line...

...and a straight cut is made using the piece of wood as a guide.

saltytri · Aug 13, 2012

The sides are returned to the mold and a line is marked on the other side.

The goal in making the cuts is to have the joint a bit tight so there is no gap. The clamp on the mold is then used to bring the two cut surfaces firmly together after glue is applied.

The heel block is glued and clamped, and it's done.

luluwrites · Aug 13, 2012

This is so cool! Thanks for letting us watch. You're right, that rosette looks stunning on the spruce. I had thought the mango uke would be my favorite, but now I'm torn. Keep the pics coming!

saltytri · Aug 13, 2012

Both of the Twins will get simple, narrow bindings. Since there will be no additional purfling, solid linings will do and the additional bulk of kerfed linings won't be necessary. Eight strips of mahogany were sanded to size and taped together at the ends before going into the bender. The tape keeps them from sliding apart during the process so that they all end up bent in the same place. After bending, the strips were left in the bender overnight and then removed and again clamped to the bender form in open air for a day or two. The result was very little spring back so they ought to install nicely into the sides with a minimum of drama.

Kerfed linings are easier to install so why bother? First, I like the clean look of solid linings. Second, since the solid linings are narrower, there is more vibrating surface on the top. This may not really make any measurable difference in the sound but it can't hurt. Third, the whole point of kerfing is to allow easy bending. Solid linings are stiffer and, therefore, probably lend more strength to the assembly. Again, this is supposition but it makes intuitive sense.

ksquine · Aug 13, 2012

That's some very pretty mango wood. I'm looking forward to seeing them completed (and sound clips)

soulman · Aug 14, 2012

Hi
Nice setup with the bender. Timbers look great

saltytri · Aug 14, 2012

So, how to make a nice rosette? A metal lathe isn't in the usual bag of tricks for an instrument builder but it certainly can be useful. A piece of PVC pipe was chucked up and turned to the correct diameter for the rosette. A strip of ebony was then glued to the PVC with CA. One end of the strip has to be tapered to make a scarf joint.

The lathe is then spun up and the ebony cut to uniform thickness.

This is repeated for the maple center of the piece...

...and then for the outer layer of ebony.

Finally, the rosette is sliced from the assembly and it's done.

Next Up: The Curly Twins

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