The right drying process

[Boomer 87]

Ok so I've been doing a bunch of chainsaw milling. I have milled mostly oak and Cypress. Almost all have been done at 2.25 thick. I've sealed the ends so they don't dry to fast. Right now they average 14% moisture.
These slabs are all stacked inside my shop but it's not heated or air conditioned. I have plaster laths two thick in between each one.
Question is I've had a couple slabs curl, one side concave other convex. Am I doing something wrong to make this happen or can I not control this by any means.
I have flipped the curled ones so the high spot in the center, and stacked weights on them, hoing to get them to straighten out, but that may be all for nought. Any ideas or just wait till completely dry and try to plane them flat again.

 

[Rosss]

Not an expert,
two things I am aware of is
that if one side dries faster than the other then it tends to pull to the side that is drying faster as it contracts.

second is that the wood shrinks at different rates depending on if the grain is running vertical in the slab or across the slab. Slabs with both types of grain would maybe be harder to dry strait?

I will be following this to see what those with more experience have to say.

 

[Brian72]

Try some ratchet straps around the pile. Put them on as soon as you get it stacked and stickered.

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[Boomer 87]

Never thought about that

 

[Brian72]

Never thought about that

It'll keep everything nice and tight during drying. You'll never completely eliminate movement but this will certainly keep it to a minimum.

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[scheffa]

Ratchet straps help, make sure they are inline with the stickers, also check the tension on them periodically as the timber shrinks the may need another few clicks to keep tension.

Stack them out of direct sunlight if possible to prevent the initial moisture loss happening to quick.

Some things are out of your control, a slab that has lots of knots, crotch wood, reaction wood etc will be a lot more unpredictable in its drying characteristics and harder to control

 

[Bmac]

Post above is completely correct in that you will never eliminate some movement in your slabs. Weight on top of the stack (which is what I do), or ratchet straps help. Also grain direction and natural built up tensions within the log or slab will cause some movement. Are the slabs from the center of the log or edges? Slabs from the center will have the pith and may cup in the middle, but simply cutting the board/slab down the middle length wise results in two boards that are quartersawn. Slabs cut from different parts of the log have different tension and grain direction.

To minimize movement/distortion, you can do a few other things along with weight and/or straps. First thing is to make sure you start with a level drying platform that you put your slabs on. Second you need to make sure you sticker every 16"-24" and your stickers are placed above each other. Stickers need to be uniform thickness. Finally, milling trees that are leaning will give you more reactionary wood that could distort not only while drying but as you work with it. Same goes if you mill large branches.

Bottom line will be that you can never eliminate movement during drying, that's why you need to cut slabs alittle thicker than you need and learn techniques to flatten or process your milled lumber for use.

 

[Boomer 87]

Dad and I were actually brainstorming, a way to make our own planer if you will out of another chainsaw with a long bar.

We were thinking about building a table with machinery mover sections on top, with a chainsaw jigged up in a framework fully adjustable kinda on an angle, with the bar modified to be flat across the bottom, and feed the slab through while slightly cutting across the top untill all the curl is gone.

 

[Brian72]

Thanks for the info scheffa and Bmac. I should've given more info regarding the straps and stickering. Brain wasn't firing on all cylinders this morning.

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[busch_6]

Dad and I were actually brainstorming, a way to make our own planer if you will out of another chainsaw with a long bar.

We were thinking about building a table with machinery mover sections on top, with a chainsaw jigged up in a framework fully adjustable kinda on an angle, with the bar modified to be flat across the bottom, and feed the slab through while slightly cutting across the top untill all the curl is gone.

You may want to take a look at using a router to "plane" the slabs. It would likely be a bit slower than your proposed method, but the positives would be that you could evaluate how it is going after each pass and adjust before taking a lot of material off at once. Also you have a good enough finish after the router pass to get a good sense of what the quality of the wood and grain movement. Here is the link with some options/ideas.

https://www.arboristsite.com/community/threads/planing-slabs-with-a-router.247921/#post-4601665

 

[SeMoTony]

Ok so I've been doing a bunch of chainsaw milling. I have milled mostly oak and Cypress. Almost all have been done at 2.25 thick. I've sealed the ends so they don't dry to fast. Right now they average 14% moisture.
These slabs are all stacked inside my shop but it's not heated or air conditioned. I have plaster laths two thick in between each one.
Question is I've had a couple slabs curl, one side concave other convex. Am I doing something wrong to make this happen or can I not control this by any means.
I have flipped the curled ones so the high spot in the center, and stacked weights on them, hoing to get them to straighten out, but that may be all for nought. Any ideas or just wait till completely dry and try to plane them flat again.

@Boomer87 I have three white oak slabs that are 2 3/4" thick two of them shared a cut that took out the pith of the log. All three have cupped Not knowing what to expect is why I cut so thick. The wood workers benches I planned don't really need that thick of material but the oak log was 38"-40" diameter allowing for compensation on the overthick slabs. I thought splitting the pith wood minimize the movement as they air dry.That is true to a degree.
The worst cupped slabs I have came from furthest from the center of the log. One thing I have read, is to soak the slabs in water after cutting for a long period to swap out the sap and soften the wood before drying IIRC. Peeps use existing creeks or ponds for that purpose. Steam is also used for adjusting wood. Dad made rockers for a rocking chair from straight wood by boiling them before clamping into the curved form that was tighter radius than the end result.
That's about all I recall.
Stay safe and enjoy

 

[Mad Professor]

As mentioned the trees if cut from leaners will have stress, sometimes so much the boards will curl as they are milled. Hardwoods this is tension wood on the "uphill side". In softwoods it is compression wood on the down side.

Sawing method also effects stress during drying. Quarter sawn is more stable than flat sawn, and flat sawn from the edges will cup more easily. Wide boards will also move more than narrow ones. Any board with pith in it will not be too stable. It might be best to take wide boards from the center of a log that is flat sawn with pith and resaw into two smaller boards splitting out the pith as waste, in effect getting two smaller quatersawn boards.

End coating helps slow drying and minimizes checking. Stack on a stable level substrate. I'm small scale and use 6 X 6" beams on top of cinderblocks for a base, then a row of 3 X 4" stock to take the first row of boards, 18-24" on center, with stickers centered above these 3 X 4" supports. Make sure stickers are uniform. I rip mine from cull boards a little wider than thick. This seems a little more consistent in getting stickers of consistent thickness and it's obvious how to lay the stickers. I top the stack with some heavier boards or beams. If you have a bander you can do that next or use some sort of straps. Cover the stack to keep off rain/dew, I use plastic corregated roofing with some wood scraps on top so they don't blow away. Put the stacks in the shade if possible.

 

[CountryBoy19]

Sawing method also effects stress during drying. Quarter sawn is more stable than flat sawn, and flat sawn from the edges will cup more easily. Wide boards will also move more than narrow ones. Any board with pith in it will not be too stable. It might be best to take wide boards from the center of a log that is flat sawn with pith and resaw into two smaller boards splitting out the pith as waste, in effect getting two smaller quatersawn boards.

If I'm following this correctly, given a really large log, that may experience a lot more cupping over the width making full-width slabs is going to be tough to do?

So when dealing with the pith, rather than make 2 full-width slabs just on either side of the pith, it would be better to have a cut go directly down the center of the log, then split those 2 slabs that come from directly beside the pith (removing any remaining pith) and make 2 book-matched slabs? Or would you still have 1 slab centered right on the pith with plans to split the pith out and rejoin and do the same for the next 2 adjacent slabs if they cup too bad?

How does having access to a solar kiln affect cupping/warping while bending? It's faster than air-drying but it will still take a good while to dry a 3" thick slab in a solar kiln.