Official Luthiers Forum!

I know we use heat and water (or steam) and pressure to bend wood into shape.

My question is, what of these has the most effect on the wood?

obviously, we need the pressure to get the wood into the form/shape we want so I guess my questions is, does the heat have the most effect on the wood or the water? If you soaked a piece of wood for an extended period of time (like a week?) would it be possible to bend the wood without the use of heat? and how much springback would there be?

on the other side of that coin, can one bend wood with the use of only heat and no water?

I know this is an open ended question and I'm not looking for one specific answer, I'd just like to learn more about wood and how we can alter it's shape with the use of heat, water, pressure.

If you soak the sides for a short time or a long time frame you are adding far to much water to the process. More than the heat will cook out. This leads to the sides cupping across the grain as the bent rim dries.

The most important component is the bender's knowledge of the wood and how it reacts to moisture, heat and stress. Get it too wet it will cup, over cook and it will burn, under heat and it will crack.

Many Hardwoods I do not add moisture to bend. Most need just enough to trasfer the heat quickly in to the fiber cells.

Rightly or wrongly I have (with success) bent EIR dry in a fox bender heated with light bulbs. So at least with that piece it was possible to bend with heat and no water.

Recently I bent a fairly tight radius Ziricote cutaway over a hot pipe. I soaked the piece for a good 30-40mins and periodically wet it as needed in the cutaway area. Bending it dry wouldn't have been an option for that, nor would bending with just water and no heat!

I guess everything has to do with the type of wood your are working with, the grain orientation and moisture content (among other factors).

Cheers,
Chad

good stuff to know guys. thanks.

Water is useful in bending as a means of transmitting heat. It's the heat that does the work of making the lignin plastic, not the water. Water is not necessary with many woods. You can get partial bending working cold with water, but there you are forcing the lignin to cold creep--it's not really resetting to a new shape, and there will be a lot of springback, which continues over time. A steam box (not useful for bending guitar sides) does its work with heat. Steam is actually dry heat as long as it remains steam.

_________________
Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

I've found Supersoft to be helpful in bending highly figured woods such as koa.

_________________
A higher purpose for wood.
Rich Smith
Issaquah, WA

To answer your question!

heat is the biggest factor in bending!

Temp. depends on the species and thickness!!!

Water is only needed if you have a difficult piece to bend-NOT -for curly grain -it makes the already fragile existence in the wood more fragile.
WHY?
because it's up to -50% endgrain!-that's the curls!!

I've never had trouble bending dry wood over a hot pipe!

I only use water if the wood has taken a set!-That means it is difficult to bend-SO the water seems to help that situation!
This only happens with side already bent and need some touch-up!!!!!

You have to listen to the wood (that cracking sound is your wood)and take your time !
It's NOT a modern day -let's hurry & get this done job!!!


Mike

_________________
Mike Collins

To answer your question!

heat is the biggest factor in bending!

Temp. depends on the species and thickness!!!

Water is only needed if you have a difficult piece to bend-NOT -for curly grain -it makes the already fragile existence in the wood more fragile.
WHY?
because it's up to -50% endgrain!-that's the curls!!

I've never had trouble bending dry wood over a hot pipe!

I only use water if the wood has taken a set!-That means it is difficult to bend-SO the water seems to help that situation!
This only happens with side already bent and need some touch-up!!!!!

You have to listen to the wood (that cracking sound is your wood)and take your time !
It's NOT a modern day -let's hurry & get this done job!!!


Mike

_________________
Mike Collins

I visited the Santa Cruz Guitar Co. the other day. Everything seemed pretty standard until they said they soak sides for 10 minutes before bending. The sides I saw were left laying in the bender and didn't have any spring back whatsoever.

I've never had that experience with the sides I bend, even following the various heat/time recipes here. Do those of you who bend dry ever have results without any spring back?

I always have springback and cut my bending molds to accomidate it. If I chance not to have any springback, I will just loosen the upper and lower bout presses, reheat, and let it pop up a little. Mahogany is what I have been using, and one set of Paduk. And lots of water.

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Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I

Interesting to see how they bend the sides in a big factory. About 1 minute 45 seconds in.

http://www.youtube.com/watch?v=wtcw-59vRL0

Warren.

OMG that video makes me sick. Litterally cookie cutter guitars. Notice how the guitar sides bend after the boiling water for 15 sec? Instant bend.

Ahh, but I never thought about Poplar for endblock wood..

This one is not so disturbing, a bit more hand made.

http://www.youtube.com/watch?v=Mmfu1hqIDuo&NR=1

_________________
Here is what a Parlor Guitar is for!
http://www.youtube.com/watch?v=oEa8PkjO6_I