Cocobolo

oud272 · Jan 3, 2016

Just scored some Cocobolo that was on special from Rockler.

Never made a Ukulele out of this wood so does anyone have tips for bending. I have a Fox style bender with heated blanket.

Also what do you recon for the top, I have some Stika Spruce I could use or could go all out with Cocobolo back/top/sides.

Dave

Beau Hannam Ukuleles · Jan 3, 2016

any soft wood is good for a top (spruce, cedar, redwood) , NOT cocobolo though.

Jim Hanks · Jan 3, 2016

Cocobolo can be used for the top - I have one - but probably not recommended unless you live in Nicaragua.

oud272 · Jan 3, 2016

Hi Beau Hannam Ukuleles,
Interested in the reason for not using Cocobolo for the top, I see that cocoboloukuleles.com uses it. Not at all doubting your guidance, just interested in learning more.

Dave

sequoia · Jan 4, 2016

I love this wood. I love the color and the pores and especially the black grain lines. I've found it bends fine being an oily wood and have had no bending problems. However, it has two very major drawbacks: (1) That sumptuous color fades over time to an unappetizing brown color. Oh well. Nothing is forever, carpe diem, and (2) it is a toxic wood. no doubt about it and should be handled with respect. I was bending some a while back and suddenly felt quite light headed and just plain weird. I went outside of the shop and after a couple minutes of fresh air felt fine with no residual effects (at least that I know of). I have no opinion on its suitability as a tone wood having never made a cocobolo soundboard.

Jim Hanks · Jan 4, 2016

oud272 said:
Hi Beau Hannam Ukuleles,
Interested in the reason for not using Cocobolo for the top, I see that cocoboloukuleles.com uses it.

I'm not Beau, but I'll give you my answer. Keep in mind that it was not the first top wood that CU used and I believe it took them a few trials to figure out how to make it work as a top wood. No problem for them since it is (relatively) plentiful where they are, but might be a problem for you with a limited supply.

oud272 · Jan 4, 2016

Thanks for the info. Still deciding coco vs stika, although I might give it a go as I will be able to get 12 back/top sets out of the plank.

Ukulelerick9255 · Jan 4, 2016

I agree with Beau....I have a baritone in cocobolo and a cedar top. I'm guessing but I think cocobolo as a top would be to stiff and would be overdrive on the trebles. You need a softer top to add some warmth to the brightness of the Cocobolo back and sides. I prefer redwood to the cedar as it gives the best of both worlds it has the warmth of cedar with a bit of the brightness of spruce.

DennisK · Jan 4, 2016

Ukulelerick9255 said:
I'm guessing but I think cocobolo as a top would be to stiff and would be overdrive on the trebles.

The problem is the density. It does have higher Young's modulus than typical top woods, so it will be stiffer at a given thickness, but for that you can just make it thinner. However, because stiffness drops so quickly as you reduce thickness, it will still weigh over twice as much as spruce when you get it to the same stiffness.

To make a coco top work, you'll need to make it super thin and use stiffer bracing than usual. Probably a lattice pattern. Or just make it a thin veneer over a softwood top.

oud272 · Jan 4, 2016

DennisK said:
The problem is the density. It does have higher Young's modulus than typical top woods,

Yep, I see your point, Koa, Myrtle Wood and Stika are similar with Coco. being almost twice that of Koa.

I've been convinced to stick with Stika.

Hluth · Jan 4, 2016

I’ve noticed a lot of sap wood in cocobolo ukes being marketed these days and that tells me that they are made mostly from small trees or first cut flat sawn slabs. This isn’t surprising since it’s an endangered wood, and high quality quarter sawn coco heart wood is hard to find or afford these days. I would avoid using it as top wood because it doesn’t produce the range and quality of tone that I prefer. That being said, any sound can be put to good use by the player and if it looks good, why not?

Beau Hannam Ukuleles · Jan 4, 2016

My reasons for saying cocobolo is a stupid choice is that it is to heavy n hard.

It might make a decent enough uke, but why go for decent enough when you can put on any soft wood and have a great uke????

DennisK · Jan 4, 2016

Hluth said:
I’ve noticed a lot of sap wood in cocobolo ukes being marketed these days and that tells me that they are made mostly from small trees or first cut flat sawn slabs. This isn’t surprising since it’s an endangered wood, and high quality quarter sawn coco heart wood is hard to find or afford these days.

Cocobolo's humidity expansion rates are low, so flatsawn isn't too bad. Quartersawn walnut moves more than flatsawn cocobolo. Though coco is more brittle, so it will crack with less RH% drop from where it was braced. But you can brace it a bit drier since high humidity tolerance is dependent on the wood's expansion rate, and the brace glue area.

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