Sides curved after bending? (Full Version)

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Vince -> Sides curved after bending? (Feb. 10 2016 18:39:15)

Sides curved (from top to back) after bending.
What's wrong. I let my sides try in a jig and hold it with spring clamps in shape.
Maybe I have used to much water while bending in my bending machine. The wood is highly figured maple.
Should I wet the wood again and let it dry in the bender?



Peter Tsiorba -> RE: Sides curved after bending? (Feb. 11 2016 1:52:16)

Hello Vince,

Occasionally, I have come across the same problem. As far as I can tell, it is usually due to the characteristics of that particular set of wood. With maple, especially, the most spectacular figure tends to focus around tension/compression areas of the tree, i.e. near the crotches and tree limbs.

Yes, try to wet the wood again, and dry it in the bender. If that does not help, consider either laminating the sides, or using extra cross-grain side braces.

In general, I try to bend maple with more heat and less water.



Vince -> RE: Sides curved after bending? (Feb. 11 2016 6:14:07)

Hello Peter,
thank you for your advice
I will wet the wood again in the particular areas and press the side in my mold which I use for laminating sides too. After a view days I reinforce the sides in this spots with a stiff side brace.
Before closing the box, I reduce the heavy side braces to normal or nearly normal size.
I hope this solves the problem.
The client gave me this particular wood (own tree) it was cut very well and was try. He loves it so much and there is no more left for sides.



Anders Eliasson -> RE: Sides curved after bending? (Feb. 11 2016 11:11:43)

What is the thickness of the sides? (just curious[;)])



Vince -> RE: Sides curved after bending? (Feb. 11 2016 11:39:07)

Hello Anders,

2,0-2,1 mm



Stephen Eden -> RE: Sides curved after bending? (Feb. 11 2016 13:14:09)

It happens more or less with most woods regardless if you use water or not. Mainly on highly figured woods. I heard a theory that guitar sides partly got thicker to give more room to remove the cupping. I don't know how true that is though. I would just sand if it's only say 0.5mm or so worth of cupping I would just sand it out



Vince -> RE: Sides curved after bending? (Feb. 11 2016 13:41:38)

When I sand or scrape this to a flat surface I create a new design for soundports![:D]



Stephen Eden -> RE: Sides curved after bending? (Feb. 11 2016 16:26:59)

Ahh that cupped huh. I remember something like that happening when I was an apprentice to a set of BRW we working on. We decided to brace the side to get the cupping out. It worked to some extent but some sanding was still required.

Something for the future though, try bending with no moisture. I will add moisture to a particularly stubborn piece of cypress but that's about it



Andy Culpepper -> RE: Sides curved after bending? (Feb. 11 2016 19:15:08)

This only happened to me once, with a set of Indian Rosewood on my 3rd guitar. It was bad enough that it couldn't be scraped out, and side braces didn't really help.

Everyone I've talked to says it just happens on certain sets of wood, but I think bending by hand with a bending iron/hot pipe/whatever helps.

I've had other side sets that seemed like they wanted to ripple, but I was able to see it as it was happening and control it better, to the point where it could be scraped/sanded out.

When I used to use a bending machine, you would just spray the sides a bit and put them in, and not look until the next day, so you didn't know at what stage it happened and you couldn't address it as it was happening.

I'm sorry to hear that it happened to you with a special set of wood :/



Anders Eliasson -> RE: Sides curved after bending? (Feb. 12 2016 8:16:00)

quote:

Hello Anders,

2,0-2,1 mm


Maple is definately not the easyest wood to bend. It doesnt like to much water and heat. If its very figured, it almost falls apart if bend to wet.

I´ve had my trouble bending violin sides on a hot iron. They are only 1mm thick and react heavily to both to much water and heat. Another thing is that if using very little water it scorches very easily. There´s only one way and thats patience, bending slow with medium heat and little water. Just sprinkle small parts. The center piece of a violin side ( the 'C' ) has a very tight curve. The good thing about maple is that it doesnt "locks" as cypress does when getting to hot, so you can always continue with the piece of wood that you are working on.

When bending highly figured wood for guitars, I use the 'wet paper' method: The wood is left dry and paper (not printed!!) is wetted and put on both sides of the wood before it goes into the bending machine.



Vince -> RE: Sides curved after bending? (Feb. 12 2016 9:34:58)

For bending in the machine I wrapped the sides in one layer packing paper and spray the paper tripping wet.
In this case this was too much.
Next time I will press the Sides in a mold for a view days after bending, with a thick layer paper inside and outside the Side for better drying. I am sure that this helps to hold the shape better.



constructordeguitarras -> RE: Sides curved after bending? (Feb. 17 2016 23:02:26)

quote:

Another thing is that if using very little water it scorches very easily. There´s only one way and thats patience, bending slow with medium heat and little water. Just sprinkle small parts.


On guitar sides, I avoid scorching at the waist (the most extreme bend) by placing a wet rag between the bending iron and the side. This also creates more steam, which is helpful too.



Anders Eliasson -> RE: Sides curved after bending? (Feb. 18 2016 7:40:06)

quote:

On guitar sides, I avoid scorching at the waist (the most extreme bend) by placing a wet rag between the bending iron and the side. This also creates more steam, which is helpful too.


Have you bent maple this way?
To much moist is a problem when bending highly figured maple. And I believe that Vince is using european maple? which is different from the american maple sorts.



Stephen Eden -> RE: Sides curved after bending? (Feb. 18 2016 12:45:08)

I ruined my first set of flamed maple doing exactly that Ethan. The end grain sucked all of the water in and as it expanded turning to steam pop went the side! I have found it easier to simply turn the heat down to avoid scorching and work in small bending increments.



constructordeguitarras -> RE: Sides curved after bending? (Feb. 18 2016 13:19:36)

quote:

The end grain sucked all of the water in


But isn't the waist far from the end grain?

Anders--Yes, I have bent maple that way, including birdseye. I bought the birdseye from Turkey and I'm not sure where it's from. Probably from America, which would be funny.



Stephen Eden -> RE: Sides curved after bending? (Feb. 18 2016 13:30:22)

In flamed Maple the flamed look it caused by the grain constantly changing direction in an S shaped pattern. Think about the wood having some extreme run out then pulling a complete U turn. So where ever there is flame there is end grain



Anders Eliasson -> RE: Sides curved after bending? (Feb. 18 2016 17:28:01)

quote:

I ruined my first set of flamed maple doing exactly that Ethan. The end grain sucked all of the water in and as it expanded turning to steam pop went the side! I have found it easier to simply turn the heat down to avoid scorching and work in small bending increments.


youps, thats 100% my experience as well. Work slow and as dry as possible. If not, it pops.
We have birds eyed maple in Europe as well. Birdseyed maple is as far as I remember flatsawn, so bending it is a completely different story.



David LaPlante -> RE: Sides curved after bending? (Mar. 7 2016 14:31:52)

You may be able to "massage" these by re-heating the specific areas (on a bending iron) and reclamping flat.
I use narrow "sticks" of thick (1/2") plexiglass to flatten the localized cupping at least so it can be further flattened with a side stiffener or sanded flat.
Quartered wood seems less prone to this and flatsawn seems more prone.
Something like bird's eye maple is all over the map in this regard.



Vince -> RE: Sides curved after bending? (Mar. 7 2016 15:12:58)

I reclamped the sides in a mould for 2 Days. Happy!!!!!!



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