Encouraging warping?

[Will Spalding]

Hey all, new guy here with a question about warping.
I have access to lots of red and white oak due to an ice storm last year. I've given up trying to do a second turning with it once its dry but am instead bringing it to final thickness while green and letting it warp. I'm interested in maximizing warping for some unique shapes.
Tricks I'm trying: very thin walls with slightly thicker bottom
: using packaging tape in certain areas to encourage uneven
drying
: experimenting with drying in paper bags vs open air drying

Any suggestions on best way to get the most warp for my buck? Something I could soak the bowl in? Haven't tried soapy water yet but gonna give it a shot. Any and all suggestions welcome!
-Will

 

[hockenbery]

Will,

I would suggest turning thin to an even wall thickness.
1/8 inch or 3/16th. This lets the wood move.
Second to get unusual shapes you need unusual grain patterns.
If you turn a traditional natural edge bowl from straight grained wood it will warp in a symmetrical pattern.

Crotch wood will have wood going in different directions, cut the wood on the bias, live oak with twisted grain does cool stuff.

Have fun.
Al

 

[hockenbery]

Bending will work with some woods.

You can makes some type of frame and use rubber bands to put a small pressure on the wood.

Bending the long grain is less likely to crack the wood.

If you have straight grain you can steam it or boil it an bend it to frame.

 

[MichaelMouse]

The microwave is one way to play. I have used it in the past to make round things out of potentially warped ones, and it will work in reverse.

Not sure I'd go so thin as suggested on a face grain piece. Quarter inch or even a bit more is certainly fine. You just have to remember that you can't shorten a piece, only narrow or make it shallower. Push on the endgrain at considerable risk, but feel free to distort along the grain, which is what happens naturally. The business of making all places the same thickness is meaningless. Feel free to leave enough wood at the bottom of a thin piece to keep it from tipping or blowing away. Lower center of gravity can be your friend on a windy day on the craft circuit.

Here's a piece that I couldn't quite get back to completely circular. http://i35.photobucket.com/albums/d160/GoodOnesGone/Cherry-Top.jpg Thin, in this case, is good, because thin is only the long grain. Endgrain bottom is 1/2", pretty much left alone.

Microwave in a plastic bag if your microwave and the piece are capable, this will give you a fine imitation of a steam box. Otherwise, you'll have to boil a lot of water and soak a while. Use cotton gloves under, rubber glove over when you handle, and have your forms or bands ready when you pull the piece. It's never plastic that long. Suggestions include three-four uprights spaced inside a couple of band clamps to make a neat clover, or clamping the rim down in a couple-three places either inward or out.

 

[hockenbery]

Will,

If you are an AAW member go to AAW journal June 1994 page 36.

Peter smith article on Potato chip bowls - they look like potato chips when dry.


Generally the thinner you turn the more movement you get.

Al

 

[Bill Boehme]

Oak may not be the best choice if you want warping -- not that it doesn't like to warp -- it does, but it also likes to split more than most other wood. Turning thin may help, but maybe not. By the way, it is most likely too late by many months to turn the wood and expect much warping.

If you want really significant warping, turn freshly cut maple to less than 1/8" and use rubber bands and clamps to control what sort of warping you want to achieve. An example is the type of work that Johannes Michelsen does.

 

[Gretch Flo]

Greenfield, Ma

[QUOTE
-Will[/QUOTE]
Hey Will- You live in my home town that I am visiting in 3 weeks. Send me an PM email at Flo@msu.edu

 

[hockenbery]

As Bill said is definitely a master of thin and takes advantage of warp.

A couple more thoughts
Shallow Bowls or trumpet shaped bowls with wide rims will show warp better than tall narrow bowls.

As Bill said your wood may be to dry to do much. A quick way to see what will happen is to cut thin slices on the bandsaw.
Cut some 10x10x 1/16 slices ( or 6x6x 1/16) and watch what they do. 1-2 days will show the potential.

Quarter sawn pieces won't warp much, Face grain are going to move, slices on bias will move irregularly, crotch pieces and those with large knots are going to move in a wavy fashion as. The grain has different orientations.

Limbs with bends will have irregular grain too.

Have fun

 

[Will Spalding]

Thanks for the suggestions guys. I think the wood I'm working with may be a bit too dry at this point to get the results I'm looking for. The boiling and bending idea is a good one so I'm gonna give that a whirl. I have an old lobster pot and propane burner that'll be perfect for the task.
Interestingly checking has so far not been a problem... probably further proof of a low MC.
Thanks again... success or fail, I'm having the time of my life 🙂

 

[MichaelMouse]

Red oak takes forever and a week to dry if you leave it in the log. White not far behind. Well to take a look at this illustration from the Wood Handbook put out by the Forest Service. http://i35.photobucket.com/albums/d160/GoodOnesGone/LogEnd.jpg The wood contracts upon itself, so the greater amount of continuous wood you have, the greater the absolute amount of natural contraction. It does not contract along the grain at all, for practical purposes. The orientation of the rings give a clue to direction of movement. More air in the lighter earlywood than the heavy later, so greater contraction potential there. As the softer stuff contracts, it tries to pull across those annual rings, closing them up, so you can use them as predictors. All of which is great when the wood's fairly regular, but gets impossibly complicated when the whole thing runs six different ways. Which is why the only predictable warp is what you do, and why I suggested steaming.

One other way to get visual interest is to use what I call an "unnatural" edge piece for the turning. Here's one in progress. http://i35.photobucket.com/albums/d160/GoodOnesGone/Unnatural.jpg

One finished. http://i35.photobucket.com/albums/d160/GoodOnesGone/Weirdo.jpg

Ugly attempt that failed to thrill. http://i35.photobucket.com/albums/d160/GoodOnesGone/Mistaken-Conception.jpg

A potato chip in hard maple. http://i35.photobucket.com/albums/d160/GoodOnesGone/Firewood-One.jpg

Oak splits so straight and easily with those radial flecks that you may not get a good deal of variety where things are straight, though near branch roots and through branches might give you as much visual whimsey as anything you tried to steam and influence.

But the wood is lovely even where it's straight, so don't toss it into the fireplace. http://i35.photobucket.com/albums/d160/GoodOnesGone/Red-Oak-Profile.jpg

 

[robo hippy]

As one who prefers warped bowls, I think it has as much or more to do with the wood than it does what and how you dry it. The higher the water content, the more shrinkage you will get. So, best time to harvest would be early spring. Madrone is my favorite. I had a 22 inch diameter bowl that finished moving at 25 by 17 inches, and it did this without any help from me. When it warps, it is never uniform. Sycamore is another one that holds a lot of water, and warp a lot, but the warping is pretty uniform. You can apply pressure, always in compression, and never in expansion because if you try to push out from the inside, it will split every time. Do round over the rims of the bowl. 1/4 to 3/8 inch thick is great for utility bowls. Less than that, and they are more 'artistic' or 'dust collectors'. I always put a couple of wraps of the stretch plastic film around the rim. This does help prevent rim cracks, but contributes nothing to the final shape. Any figured wood, especially the buttress part on the base of the tree will warp a lot and go very 3D as it dries. With this type, you have to sand before you dry it, other wise, you will loose all the texture when you sand it out. If you power sand your regular bowls, you need lathe speeds of around 20 rpm. Any higher and you can't keep your abrasives on the wood. Most phase converters can be programmed to speeds this low. Standard is for them to shut off at 50 rpm. I think there was a long thread in the tips section here on how to do that with the PM and Jet lathes. I have a Robust, and Brent helped me program it down. There is concern about running at those speeds, but I found the motor runs cooler than when I am turning. Almost no load when sanding.

robo hippy

 

[MichaelMouse]

Water content of the cellulose and hemicellulose comprising the cell walls is about 30% of dry weight when it's saturated. Anything else is unbound water, and does not affect shrink.

 

[john lucas]

Soak it in water, heat it in the microwave and bend it, slowly. As MM said bending with the grain works better than trying to bend it across the grain. If you want to bend it much, turn it thin. Buy Johannes Michelson's DVD on making hats and you will learn a tremendous amount although he doesn't use the microwave. I only suggest that because I assume the bowls are already dry or partially dry. Re wetting them and then heating them in the microwave makes them easier to bend.
Study how wood moves and warps and you can learn to take advantage of those abilities by orienting the wood the proper way on the lathe.

 

[Bill Boehme]

Just to clarify things, natural movement that is the result of drying can be called warping although flat woodworkers break it down into various subcategories.

When we do things to force the wood to move in certain directions as it dries, it probably ought to be called "bending" rather than warping.

 

[Will Spalding]

^^
Agreed. I'm looking for a pretty wonky effect and it hadn't even occured to me to try to bend the wood manually.
You guys are a wealth of knowledge and there was more than one suggestion that sent me to my dictionary.
I'm pretty new to turning and am only beginning to understand the properties of the species/cuts and how it responds to the drying process... I might be getting ahead of myself by trying to manipulate it but I'm gonna do it anyway :cool2:
Thanks again for all the suggestions. I'll post pics of the disasters that are sure to follow...