Goncalo Alves Side Bending

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Bob Connor
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Goncalo Alves Side Bending

Post by Bob Connor » Sat Oct 06, 2007 10:54 am

Dave and I bent some sides yesterday out of Goncalo Alves.

This would have to be the toughest wood we've encountered. We soaked it in Supersoft but this had no effect on it at all.

Winding down the waist in the bender you could feel it fighting all the way and this was on an O model so no tight waist to contend with. Got the heat up to 170C.

Got a couple of little cracks in the waist and upper bout but nothing that couldn't be fixed.

By contrast we did some Blackwood straight after and this bent like butter.

The tap tone coming out of the back of this thing, however, is super.

I was given this lump of wood last year as Brazilian Rosewood however it turned out to be GA.

Apparently Australian Furniture Timbers were selling GA a long time ago as Dark Brazilian Rosewood so quite a few people thought they were buying Dalbergia nigra.

The Goncalo I reckon will make a super guitar . this one will have an Adi top.

Bob

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Dennis Leahy
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Post by Dennis Leahy » Thu Oct 11, 2007 3:15 am

Bob,

We'll have to get Grant Goltz in here to talk about bending Goncalo Alves. (I know he has successfully bent it, and has quite a bit on hand.)

170°C (338°F) sure sounds like enough heat. How long did you have it at that temperature before cranking it down? Did you use foil and wet paper in the sandwich?

Dennis
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Post by Bob Connor » Thu Oct 11, 2007 2:40 pm

Dennis

We started bending at 150C (probably 5-6 minutes) and it was wrapped in foil and craft paper, plus a few days with Supersoft on it.

It didn't even feel as though it was going to become pliable with the heat.

This wood has had about 30 years drying and killed a number of bandsaw blades resawing it. One dense piece of timber.

It'll end up fine but we've got another set that'll get bent eventually.

I'm looking for some tips to make sure the next one is a bit easier.

Bob

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Dennis Leahy
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Post by Dennis Leahy » Fri Oct 12, 2007 2:22 am

Hi Bob,

I have only bent 2 sets of guitar sides (EI Rosewood, steeped in hot water for 20 minutes) and Bubinga (with a silicone blanket setup.) So, anything I say here is mostly conjecture...

I wonder about the thickness of the material. Was it thicker than .080"? I though it was interesting when I was at Grant Goltz's place, and we were running my sides of various species through his thickness sander. At first, he uses calipers to measure the thickness, but ultimately, he extends the pieces and wobbles them a bit, and finally says, "this one's about right" when he feels the wood will allow itself to be bent. Perhaps the particular Goncalo Alves you have needs to be even a bit thinner than the "norm"?

I wonder about the ability to accurately get a temperature reading from any of these setups. I know there's a range of temperatures, not some fixed point like a melting point that we're dealing with, but I have wondered about my own (kinda high-tech) silicone blanket/temperature controller setup and whether it should be calibrated. (I'm not doubting you, I'm just doubting my own setup, and wonder if that could be a consideration.)

I wonder if there are some woods, especially extremely stiff woods with a high resin content, that are better off being bent after boiling/steeping. Now, 212°F/100°C is probably not enough heat for plasticizing Goncalo Alves, so it might be a matter of boiling then quickly transferring the hot wood into a silicone bending blanket sandwich to take it the rest of the way... that sounds like quite a hassle though.

Actually, my gut tells me that the wood was not yet plastic, if you had to fight it that much. I'm not sure if it was Tom "mandomaniac" Durr or Grant Goltz that came up with the idea of starting the bending process vertically, but they now both do it that way. They create the silicone/spring steel/wood sandwich, clamping the end of the sandwich to the male bending form at the end of the lower bout - sticking straight up. The upper layers of the sandwich are held together with a few spring-loaded wooden clothes pins. Then, they turn on the heat. They do not attempt to do any bending until the wood in the sandwich becomes plastic and the sandwich starts to sag on its own. Then, they clamp the lower bout, then the waist, etc. I haven't tried this yet, but I will on my next side bending tasks, as I will be bending figured Katalox and Granadillo sides.

Pardon me for mentioning Grant Goltz so much, in this and other posts, but he has become a mentor to me.

Dennis
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Post by Bob Connor » Fri Oct 12, 2007 6:03 am

Thanks for that Dennis

The sides were at .075 so I really don't want to take them down much more than that as I like to keep them as stiff as possible.

I certainly would like to hear Grant's thoughts on this.


Bob

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Post by Dennis Leahy » Fri Oct 12, 2007 6:34 am

Wow, I wouldn't want to go thinner than that either. Must have been one hell of a strong tree!

Dennis
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Post by Bob Connor » Fri Oct 12, 2007 6:54 am

The back is attached to the sides now Dennis and it has a very vibrant, rosewoody tone to it. Sort of that mettalic ring that BRW gives. So I reckon it'll sound very nice if we get the top right.

This guitar is part of a set of four 0-18 style guitars.

1. Goncalo Alves/Adirondack Spruce
2. Tas Blackwood/King Billy Pine
3. Sassafras/Sitka
4. Hard Rock Maple/Engelmann

We want to finish these all at the same time and string 'em up on the same day to have a comparison of the different woods.

Bob

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