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Before and After - Wet and Dry

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Project by Chris posted 527 days ago 759 views 0 times favorited 4 comments Add to Favorites Watch

This is a pencil cup I turned from a scrub oak that fell in a storm last year (not Sandy, the latest). Sorry for the photo quality – its all off my cell phone camera and the lighting was different. What I wanted to show was how dramatic the deformation of the cup was as it dried. I’ve had others that deformed less and split straight through. It might be that this one is pretty thin – 3/32 at the edge and fairly thin all through. That doesn’t make all that much sense to me but I’ve heard other turners say it can have that effect.

Thanks for looking,

-- Chris





4 comments so far

View dustprocrastinator's profile

dustprocrastinator

61 posts in 1185 days


#1 posted 527 days ago

Have you ever tired the rough turning method?

View LesB's profile

LesB

1043 posts in 1942 days


#2 posted 527 days ago

I see a couple of problems with this particular piece.
First is that your wood was probably not completely dry; less than 12% moisture.
Second you were turning across the end grain with the center of the limb passing through the top part of your cup. That caused wood movement around the center of that grain as well as laterally. If you cup had been shorter and cut below the center of the growth rings there would be a bit less movement. Try turning the cup into the end grain not across it. Yes you won’t see the grain pattern on the side but you will not have the warping you got here. In addition oak tends to have more movement with changes in moisture than some other wood. Even if you start with 8% moisture the wood will gain and lose as the atmospheric humidity changes, causing movement. I also see some sap wood and that will move differently than the mature wood.
Scrub oak type woods grow in feast or famine moisture conditions so they are often quite dense and hold a lot of moisture which takes a long time to dry out if you are just using an ambient air drying method.

Also when you have a piece like this that still has too much moisture do what dusprocrastinator says above. Rough turn the shape leaving it about 3/4” thick, or more on larger things. Then either let it dry before the final turning (where you can remove most affects of any warping) or try one of the micorwave drying methods. I could explain that here but there are lots of articles on the internet you can read. It works great I use it all the time.

Good luck with your next piece.

-- Les B, Oregon

View Jim Jakosh's profile

Jim Jakosh

10219 posts in 1604 days


#3 posted 526 days ago

You never know which way it is going to go. I had one big cherry bowl I turned green and then I made a lid for it before I knew any better. While I was making the lid, the bowl warped. So, being new to this game, I turned the lid to fit the narrowest part of the bowl and it fit fine. the the bowl dried more and went back to a more round shape and the lid is loose.

The secret is to turn the piece to a uniform wall thickness, much thicker than your finished piece. Then the wood will move as it dries, but it usually will not crack as if it were solid, because it has some flexibility. Put the bowl in a pile of shaving for 6 months to year and then finish it. I like to leave the wall around 3/4” to 1” thick. It does work well.

The piece you have is not uncommon being that tall and that thin. Sometimes the warp is seen as character to the piece ( just don’t make a green lid for it!!!!! ).
Hey, it will still function as planned and can not be duplicated exactly as you have it!! Mother nature will see to that!!

Thanks for sharing!!..............Jim

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!!

View Chris's profile

Chris

338 posts in 1856 days


#4 posted 526 days ago

Thanks guys. I guess I should have been more clear. I do use the rough turning method on wet wood when I am aiming for a round vessel, or just use dry materials. I expected this piece to warp, I just wasn’t expecting it to warp this much or so asymmetrically. Having the pith run through the piece as well as having as much sapwood as there is was a choice. Frankly I expected the piece to crack, but it was worth the firewood to see how thin I could get it and just what it would do when it dried. Generally when i do this I don’t have the pith in the piece and the bowl just distorts symmetrically into an ellipse, and all I do is clean up the foot to prevent rocking.

And as Jim pointed out, it still works as a pencil cup!

Thanks again,

-- Chris

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