Wood is cupping as it is being cut.

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Re: Wood is cupping as it is being cut.

Postby jseiler » Sat Feb 14, 2015 8:07 pm

You might try recessing a piece of baltic birch ply into the back before engraving. Its surprisingly warp resistant.

-- John
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Re: Wood is cupping as it is being cut.

Postby esteeme1 » Sun Feb 15, 2015 4:22 am

I was cutting two panels about a month ago. I had to alternate one of the side I was cutting on because of a defect. Here is the end result.

I notice when I carved into the peak of the growth rings the piece would cup. But when I carved into the dish side of the growth rings cupping was minimized. So I had another project and applied that principle and was very pleased with the results.

in any case the picture is all the proof I need.
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DSC04435.jpeg
Carving on the top of the growth rings
DSC04438.jpeg
Carving on the dished side of the growth rings.
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Re: Wood is cupping as it is being cut.

Postby Larry Stobbs » Sun Feb 22, 2015 4:25 pm

Depending on where you get your wood, you can get walnut cut thicker, I have bought 8/4 walnut before that is Kiln Dried and it worked pretty good for some of my projects and I didn't have to glue them up. I cut a bunch of military/police/fire emblems out of solid walnut using wide boards (13 to 15 inches) and typically if the wood is kiln dried correctly there is a minimum amount of cupping. The trick I use to help is to leave it rough cut the way I get it from the saw mill and wait until I am ready to carve and then I run the wood through either my planner or panel sander to get the piece flat and then I carve. I also don't give a lot of time between when I finish the piece and when I start applying my finish as I have found that if you leave it set for several days it will start to cup slightly probably from the moisture in the air
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Re: Wood is cupping as it is being cut.

Postby dhellew2 » Sun Feb 22, 2015 7:56 pm

Unless I missed it, I didn't see anything about flatsawn wood, which is the most common wood because it yields more wood and it shows off the grain
Kiln dried wood is typically between 10% and 12% moisture at the center of the board
It can take up to a year for wood to acclimate to your climate
The best method is to cut the wood into 3" strips, alternate the rings up and down but keeping the edge tapers the same direction and glue them back together

This is what I do:

Looking at the rings at the end of the board to determine the center of the tree
Make the carving on the tree center side of the board; this often helps reduce cupping

Flatsawn wood almost always cups towards the outside of the tree, the rings are wetter and less dense, therefore, shrink more
Cutting on the tree center side relieves some of the stresses, sometimes it will even cause the cupping towards the tree center

One can never be certain what will happen to wood :?
sunset warrier with frame.jpg

This carving is red oak, cut into strips, and it still cupped towards the carved side
warrier sunset warping.jpg


Notice all three pieces cupped towards the carved side anyway
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Re: Wood is cupping as it is being cut.

Postby esteeme1 » Sun Feb 22, 2015 11:33 pm

I definitely agree cutting from the inside of the tree minimizes cupping but in this case I believe most of your cupping is coming from the center board. I believe if you would have cut it on the other side you would have minimal cupping. Look at the top board and you can see that it is mostly flat. I know that most if not all wood workers rotate/flip there boards to join them and agree it is the proper method for flat panels but when carving some considerations may need to be considered. I never rotate my growth rings but that is mainly for color matching and I only cut panels no wider than 24" I normally don't cut the entire board but cut dished carving in the center of the wood. Generally I haven't experienced to many problems with cupping but have recently noticed some.

dhellew2 wrote:Unless I missed it, I didn't see anything about flatsawn wood, which is the most common wood because it yields more wood and it shows off the grain
Kiln dried wood is typically between 10% and 12% moisture at the center of the board
It can take up to a year for wood to acclimate to your climate
The best method is to cut the wood into 3" strips, alternate the rings up and down but keeping the edge tapers the same direction and glue them back together

This is what I do:

Looking at the rings at the end of the board to determine the center of the tree
Make the carving on the tree center side of the board; this often helps reduce cupping

Flatsawn wood almost always cups towards the outside of the tree, the rings are wetter and less dense, therefore, shrink more
Cutting on the tree center side relieves some of the stresses, sometimes it will even cause the cupping towards the tree center

One can never be certain what will happen to wood :?
sunset warrier with frame.jpg

This carving is red oak, cut into strips, and it still cupped towards the carved side
warrier sunset warping.jpg


Notice all three pieces cupped towards the carved side anyway
Jim Darlas
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http://www.esteemedwoodcrafts.com/
http://www.esteemedplaques.com/
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Re: Wood is cupping as it is being cut.

Postby Phil » Mon Feb 23, 2015 2:23 pm

Hi Esteeme,

Thanks for posting pictures to show how you have had success in dealing with cupping. I noticed in the pictures you posted that each glued up board has three pieces and that rings all face in the same direction. Common practice in woodworking is to alternate the rings. This is a strategy to minimize cupping.

Phil
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Re: Wood is cupping as it is being cut.

Postby esteeme1 » Mon Feb 23, 2015 4:41 pm

Hi Phil,

I'm just thinking outside the box, "quite literally". As I said above I understand that alternating the boards prevents cupping but that considers the fact that panels are not carved on and generally the craftsman is making a table top or a much wider panel than I normally make. Again I think when carving your pieces you may have better results if you don't alternate and carve on the cupped/con-caved side of the board. I'm not suggesting that anyone not alternate the boards in everyday woodworking but when carving some considerations could be given to not.

If you look at Dhellew's pics you can see where the majority of the cupping starts and that the top panel is relatively flat and it happens to be carved on the cupped side.
Jim Darlas
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Re: Wood is cupping as it is being cut.

Postby Rcnewcomb » Mon Feb 23, 2015 6:07 pm

Again I think when carving your pieces you may have better results if you don't alternate and carve on the cupped/con-caved side of the board.


I would have to disagree. We found that alternating strips on the glue-up provided better long term results.

We learned that higher moisture content of the wood contributed the most to cupping problems while carving.
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Re: Wood is cupping as it is being cut.

Postby esteeme1 » Mon Feb 23, 2015 6:53 pm

I'm not disagreeing with anyone just stating my observations. I'm looking at the immediate results of carving into a wood panel. There are three pics on this post that lends to confirmation and again I am only making this statement concerning carved panels not furniture making. With that said I use kiln dried and it's skip plained to .825". I bring straight from the supplier and store it in a climate controlled environment. I'm not boasting just making a statement, but I have made many paneled chest and dartboards over the years and have never had any problems with call backs concerning cupping.

The majority of the problem with cupping is when people take your work and store it in a non climate controlled environment. Truthfully If the client is not willing to climate control their items I'm not to worried about it. I know this…when a product of mine is delivered it is not warped or cupped in any way. I pride myself in delivering a quality product and building something that will hold up over the years. If the client can't keep their woodcrafts out of the attic or garage that is not the craftsmen's problem.

I definitely think more attention can be given to this but I'm really not willing to waste the wood.

Happy carving friends.

Rcnewcomb wrote:
Again I think when carving your pieces you may have better results if you don't alternate and carve on the cupped/con-caved side of the board.


I would have to disagree. We found that alternating strips on the glue-up provided better long term results.

We learned that higher moisture content of the wood contributed the most to cupping problems while carving.
Jim Darlas
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http://www.esteemedwoodcrafts.com/
http://www.esteemedplaques.com/
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Re: Wood is cupping as it is being cut.

Postby esteeme1 » Tue Feb 24, 2015 12:25 am

I guess I should have taken a side view of this but I didn't. I cut this after the first the picture I posted earlier. I intentionally joined it without alternating the boards and cut it on the center/middle of the growth/tree side. Even though the pic doesn't show it well it came out as flat as a board, "pun intended". :roll:
Attachments
DSC04505.jpeg
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Re: Wood is cupping as it is being cut.

Postby dhellew2 » Tue Feb 24, 2015 12:45 am

When it's all said and done the most important thing is that the moisture content of the wood has acclimated to your environment
When I shop for wood I take a moisture tester with me

I live in an irrigated desert region and the moisture content must be below 8% at the board center

I've never found wood in the local stores under 10% moisture
Most of the kiln dried (KD) is at 12%
Surface dried (SD) is usually above 19%

Most of our wood comes from Seattle and Portland at 12% to 14%
We don't use any of this wood for 6-months
Once it has dried to =< 8% it has moved about all it's going to

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Re: Wood is cupping as it is being cut.

Postby Phil » Tue Feb 24, 2015 2:01 pm

esteeme1 wrote:I guess I should have taken a side view of this but I didn't. I cut this after the first the picture I posted earlier. I intentionally joined it without alternating the boards and cut it on the center/middle of the growth/tree side. Even though the pic doesn't show it well it came out as flat as a board, "pun intended". :roll:


Very interesting Jim. Thanks for posting.

Phil
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Re: Wood is cupping as it is being cut.

Postby plcamp » Sun Mar 01, 2015 1:56 pm

During the gluing process alternating the growth ring pattern is a must. One practice that I learned from my 'old' metal machining days is to rough the project and then follow one or both of these techniques to help maintain flatness.

After the project has been roughed you can;
A) Turn the project over and machine the back surface flat, this effectively relieves the stress introduced by the initial machining on the face side. This may or may not be a viable option if you are targeting a desired overall thickness.
B) Un-clamp the project from your work table this will in itself relieve some of the stress introduced by the rough machining. Re-clamp and continue with the finish machining.

Neither option however will guarantee a perfectly flat product when finished. Wood being an organic product will behave differently from board-to-board and is by nature somewhat unpredictable. I have noticed that deeper rough cuts tend to introduce more 'warp' than the shallower ones.

Hope this helps....Paul
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