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Cupped Pecan Slab

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Forum topic by Scott Key posted 02-16-2015 01:42 AM 1142 views 0 times favorited 8 replies Add to Favorites Watch
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Scott Key

25 posts in 3454 days


02-16-2015 01:42 AM

Topic tags/keywords: pecan slab cupped

A neighbor of mine had a mobile mill cut a felled pecan tree into slabs. I bought one on the cheap, but in the months since I bought it, the slab has cupped a fair amount. More than I would want to plane out as it would thin the slab out too much.

Does anyone have a technique to uncup or decup a slab?

Thank you!

-- -- a bad day woodworking is better than a good day at work --


8 replies so far

View WDHLT15's profile

WDHLT15

1572 posts in 1937 days


#1 posted 02-16-2015 01:51 AM

Pecan is one of the most difficult woods to dry straight. You might have to wait until it is fully dry, then rip it into several pieces, joint flat, plane, and glue back together.

-- Danny Located in Perry, GA. Forester. Wood-Mizer LT40HD35 Sawmill. Nyle L53 Dehumidification Kiln. hamsleyhardwood.com

View gfadvm's profile

gfadvm

14940 posts in 2151 days


#2 posted 02-16-2015 02:17 AM

Danny’s advice above is the only method that has worked for me. Attempts to force it flat only result in cracks and splitting in my hands.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View richardwootton's profile

richardwootton

1699 posts in 1417 days


#3 posted 02-16-2015 02:52 AM

Do you guys know why pecan is so hard to dry straight?

-- Richard, Hot Springs, Ar -- Galoot In Training

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Aj2

687 posts in 1259 days


#4 posted 02-16-2015 06:37 AM

Hi Richard never have I heard someone ask your question out loud.So here I go trying to look smart.The reason some wood are more stable than others and dry with less loss are.The tangential and radial structure of the cell.Pecan or hickory is like 5 to 9. The closer the two numbers the better mahogany is something like 3 to 4..
At least that’s the way I understand it works for me.Aj

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richardwootton

1699 posts in 1417 days


#5 posted 02-16-2015 07:24 AM

Thanks AJ, I’ve never heard that before. The reason I was curious had to do with how easily I’ve air dried walnut with very few problems, and pecan being pretty closely related to walnut, I had assumed they would be similar to dry.

-- Richard, Hot Springs, Ar -- Galoot In Training

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WDHLT15

1572 posts in 1937 days


#6 posted 02-16-2015 01:00 PM

Two things I have experienced:

1). There is more internal stress in the wood than in most species. Sawing boards releases this natural growth stress. It is paramount that the sawyer understand how to release and balance the stress as much as possible. This requires frequent turning of the cant to the 180 degree face as you saw the cant. Many pecan trees branch into several main trunks only a few feet off the ground. These multiple trunks are usually not perfectly straight/vertical, and the tree produces tension wood as a result. This tension wood moves while shrinking and drying, and is prone to cup. It is best to cut pecan from a single trunk section before any main branches divide the trunk. Like this forest grown pecan. Beautiful lumber came from this tree.

Here are some orchard pecan that had short trunks, but some very beautiful wood.

2). Pecan grain around the knots many times will “kink” or have a dip or crook that will not plane out and will cause you to have to cut out short sections to get usable wood. Pecan is a hickory, and I have found other hickories difficult to dry straight as well.

The key is to saw good straight logs, and to sticker on closer intervals with a perfectly flat foundation. I sticker at 16” intervals.

-- Danny Located in Perry, GA. Forester. Wood-Mizer LT40HD35 Sawmill. Nyle L53 Dehumidification Kiln. hamsleyhardwood.com

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Scott Key

25 posts in 3454 days


#7 posted 02-20-2015 08:18 PM

Thank you everyone for your thoughts. The information regarding the cell structure is incredibly interesting.

Sounds like my best plan of action is to rip and plane!

I read on another forum that some have had success lying the slab in the grass overnight (?). I’ll give that a shot, but I’m suspicious.

-- -- a bad day woodworking is better than a good day at work --

View daddywoofdawg's profile

daddywoofdawg

1010 posts in 1036 days


#8 posted 02-20-2015 09:17 PM

I read on another forum that some have had success lying the slab in the grass overnight (?). I’ll give that a shot, but I’m suspicious.
I have too but it was for a longer time,The idea is the wood absorbs moisture causing it to flatten.

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