Banding slabs question

[lazyflee]

I cut a bunch of slabs this Spring/Summer with my new Woodmizer. Almost always centered the pith. No kiln, just the wind and dry Montana air. Most of the stuff I cut (Spruce and Dug Fir) already down to 8-10% moisture. A few of the logs I slabbed, I banded with ratchet straps. It seems those warped badly, all slabs the same warp (twist). The ones I just stacked(no banding) a few twisted, but not all of them. My question is, when the stack is banded(strapped), do you think the whole stack takes on the twist, warp etc of one bad piece? I'm guessing just stack em and let them do what they will.

[PA_Walnut]

When banding (or stacking) slabs will take on the shape of the base. Is it flat and level?
Did you have weights on them or just straps? Generally, I prefer weight over straps, unless there's not another option.

If they are still just air dried, you can probably somewhat flatten them by adding weights and time...adding some moisture will help.

Depending on the size, usually good to figure on some twist and/or cupping and plan accordingly with thickness of cut. 

Good luck. 

[doc henderson]

lots of considerations.  it is true that straps effectively keep a bundle together.  just around wood stacks would try to pull in to the center and make a ball.  if you put a bolster top and bottom, it pulls in 2 directions, say top to bottom.  you are trying to overcome the nature of the tree, and wood fibers.  straight grained lumber will dry flatter depending on species, than lumber from a log with a lot of branches and twist.  4/4 lumber is easier to coax into flat wood, than thick wide slabs.  so straps hold it together, but could still twist and cup inside the "ring" of compression from straps.  it is nice they can be tensioned every so often.  I used metal strapping at fist, but the seals were not adjustable after the wood shrank, and would stain the wood with rust.  Nylon straps like the cheap light weight ones from HF, will degrade in the drying environment, like air drying, and only get about one use anyway.  I liked the plastic strapping I saw at @customsawyer great Georgia get away, that we used to have in the old days, pre covid.  It does not rust, and the buckles are adjustable down the road.  I strap mine every 18 inches with the stickers as tight as I can get them.  I think Jake just did a couple loose ones to keep the stack together, and staked in high piles to use the weight of stacks.  some advocate for lots of weight on the top that pushed in one direction, onto the stack over a flat bottom does the best job.  but you need space and equipment to make that happen on a large scale.  normally you stack wood as it comes from the tree in case there is a wave, or on pallets.  some with slabs advocate alternating the orientation of the slabs so they have to move against each other to cup or twist.  @YellowHammer .  instead of working together in mass.  big slabs are going to move some, and if the goal is flat smooth perfect product, you need to cut oversize, and plane or re-saw flat.  or do uber-rustic, and incorporate natural wood movement into the design.  if nothing else, my post should stir up some opinions.     @GeneWengert-WoodDoc .  if you go to the national hardwood lumber association (NHLA) website, you have to register, but not join and watch any of about 8 or 10 webinars regarding the nature of wood as it dries.  or read the paper (book) drying hardwood lumber.

[YellowHammer]

@doc henderson did a great summary.  I am not a big fan of straps unless they have bolsters on top and are kept banjo tight, but even then I'm generally not impressed with them.  They put a high load n the edges and not so much in the center of the pack.

I use weights, and lots of it, 3,000 lb per stack at least.

Sticking geometry is crucial for "grumpy" wood, especially maple, walnut and cherry thick slabs.  If all the stickered boards are stacked sympathetic to each other, essential "spooning" them they will exert the same forces in the same direction and will try to take on the same shape, and look much like Pringles.(((((((((

In contest, I like to stack with the predicted deformation opposite each other ()()() so the deformations creates high contact stresses and will try to flatten each other.  Take a stack of pringles and place them opposite each other and press them together, and the high edges will crack off easy, because they are taking all the force.  The same with stacking wood, except instead of breaking, the wood will flex and flatten, and as it dries, will stay flat.

[RussMaGuss]

Yellowhammer, I'm going to be milling up my first batch of walnut this week and was just thinking of how weight on top is probably better than banding. What is your 3,000 lb weight, a concrete slab?? I'd hate to not have done everything I could to keep the boards perfect. So far, I made the flattest pallet I could (even jointed/planed the wood) and have a nice flat spot to park it while it air dries. I'm a mason by trade, so I was going to just stack 8" block on top for weight

[K-Guy]

You only need enough weight to keep the top of the stack straight as lower down the weight of the wood itself holds the lower layers.

[YellowHammer]

Just so happens I'm milling walnut this week, and it is one of the most demanding and difficult species to produce flat wood, especially in 4/4.

Critical is the milling technique, watch carefully for boards lifting up like a carrot peel as you mill them, these boards are sure to dry with significant bow, and rotate the cant so that the boards don't lift up as you mill them, but move sideways or slip across the cant face.  These boards will dry flat, but will develop crook, which can be edged out later.

Cut as much sapwood as possible off the board, it's painful, but sapwood "pulls" and is a big contributor to drying defects in walnut, especially the thinner 4/4.  So edge them close and get at least one face 100% heartwood.

Mill the boards so that they are grain balanced, not with the axis offset left or right in a board.

Stack the boards with opposing bow, as I've mentioned before.  The easy way to remember it to stack them with the bow alternating on each full layer, "Smile UP, Smile Down".

I use 3,000 lbs of granite waste countertops I got from my local stonecutter cabinet shop, and put those pieces on pallets that I place on top of stacks with a forklift.  If you imagine pressing a flower in a book, thats what I'm trying to do.  Some of the flattest wood I ever dried was decades ago where I parked an old pickup truck on the stack. :D :D  Lots of weigh.  Make sure the weight is evenly distributed and won't cause the top boards to droop between the stickers.  So my weight pallets have the same footprint as my sticker spacing, which for walnut is at 16".

Trim the unsupported edge next to the outermost sticker, otherwise it will cause the wood to droop and cause a little "S" wave inboard of  the outermost sticker.

[Walnut Beast]

Just asking.  I thought in one of your posts or someone else that the best stable drying but not ideal. Was to leave the bark/sap outside on so to speak and put in kiln then edge when it comes out. 

[RussMaGuss]

All of that was awesome advice, thank you! 

[customsawyer]

Can't offer much more than has been said already. I stack my lumber/slabs on pallets. I also have pallets with grave stones on it that I put on top of any slabs I think will be a problem. No I didn't go grave robbing. A friend makes grave stones and I get any mistakes or ones that mess up.

[lazyflee]

Thank you for all the replies. I did find the stacks that warped badly WERE on uneven ground. Could've been the culprit. Will make better bases to stack on. Sounds like a good winter project!

[PA_Walnut]

Lots of good info here. @YellowHammer granite weights program is a great one! (I do it with big limestone mantle pieces).
My latest program is going vertical. With a big fork, I can go 6-8 pallets high, placing the problem and/or high-value material at the bottom. It also sits on a flat concrete pad, which is critical to keep it all flat.

I am going to present a SHOCK statement here that will probably insight riots  : with large slabs, I saw it 1/4-1/2" thicker than my intended finish, since WOOD MOVES. Despite my best efforts, it generally prevails and my efforts only marginally affect it. I sleep better at night. So, I saw way over, I have more time for bourbon and beer, and the extra wood chips make great compost for my wife's garden.  ;D :D

I will post some pics when I can.

[YellowHammer]

I agree, sawing thin to save money on thick, high value slabs is a misspent wood.  For my 2" slabs, I will routinely saw at 2 - 3/8" if it's a hardwood and less than 22" wide.  

[customsawyer]

The wider the slabs get the more meat you need to have on the bone for it to plane out. With the slabber cutting slabs over 40" I will saw a full inch thicker, especially on oaks.

[PA_Walnut]

The wider the slabs get the more meat you need to have on the bone for it to plane out. With the slabber cutting slabs over 40" I will saw a full inch thicker, especially on oaks.

Whoa! A full inch is a commitment! It depends on what the material is, I suppose. I have a 55" walnut about to cut. That one requires CAREFUL consideration as it's so expensive, that even the saw kerf matters.  But as @YellowHammer mentioned, it's false economy to gamble, making it too thin. The bigger and wider they get, the thicker buyers want them. Of course, when it starts equating to dollars, they suddenly come to the want:cost altar of truth.  :D :P

[customsawyer]

With my 2" slabs coming off the WM they will be less than 28" I routinely cut these at 2 3/8" and 90% or better will clean up at 2". When you add another 12+ inches in width any cup in a board gets a lot worse the wider you go. I relate it to sawing the long timbers. If you saw mostly 12' logs or shorter and you deal with stress in them. Imagine how much more stress is in a 40' log. When you go from a 28" wide slab to a 42" wide slab you just made a 1/4" of cup start getting close to 1/2" of cup. You've added another 50% in width and it will show.

[Stephen1]

I also found the length can be another culprit to movent. 13' moves a lot from 1 end to the other. Read Twist. Sugar Maple is the worst, especially with character in them. I will saw them 3" for 20" and if they are 30" wide I will go to 3.5" . If there is no character in them, they become 4/4 lumber. 
I have started marking the smile () on the logs with a crayon before I saw them, I draw circles around the log end, as it makes it easier to to see when it comes to stacking, especially when I have helpers stickering. 

[YellowHammer]

I agree, sugar maple is ornery, especially thick and figured.  

[GeneWengert-WoodDoc]

A comment about twist.  Twist is caused because the cells in the tree are not vertical but spiral up the tree for about the first 15 growth rings from the center.  Then the spiral slowly reverse but is not as steep in the rings further out.  You can prevent twist in lumber by avoiding cutting the wood at or near the center of the log (18 rings).  Of course, a 4x4 with the pith center will twist.  Log cabin builders are well aware of this tendency to twist.

[Stephen1]

A comment about twist.  Twist is caused because the cells in the tree are not vertical but spiral up the tree for about the first 15 growth rings from the center.  Then the spiral slowly reverse but is not as steep in the rings further out.  You can prevent twist in lumber by avoiding cutting the wood at or near the center of the log (18 rings).  Of course, a 4x4 with the pith center will twist.  Log cabin builders are well aware of this tendency to twist.

I learn something new each day. I have some SM that I am going to saw next week and will remember that. 18 rings is almost the RR tie.  or some new bunks in the yard. I knew about the twist when I was building my cabin, one way was good , either left or right. It's been a while, can't remember which was the best. 

[YellowHammer]

That is why I generally don't cut live edge slabs near or through the pith.  I lose the wide slabs frrm the center of a log, but also loose lots of twisting behavior.  

[Stephen1]

That is why I generally don't cut live edge slabs near or through the pith.  I loose the wide slabs frrm the center of a log, but also loose lots of twisting behavior.  

I ussually saw the pith slab and then take out the pith, leaving 2 nice boards that can be used in building of the table or benchs. I will watch this going forward with a little more interest. I always liked the slabs above and below the center, might be better to like the next ones.

[YellowHammer]

I'll saw live edge maple until I get about a 6 inch cant near the pith.  Thats about where stuff like maple gets rowdy when it dries.  I'll rotate the cant 90° and start taking 6" wide 9/4 or 4/4 lumber all the way down, boxing the heart.  Then I'll take the heart piece and sell it as a 6x6.  This way I get the best live edge slabs from the log, then the best edged lumber also.  The by the time I've sawn ups whack of logs, I've got live edge, 9/4, 4/4 and 6x6's.

Depending in the species, I'll box the heart further in or not.  I almost never saw one log completely live edge, or only 4/4 or only 9/4.  

[Stephen1]

In the past, I did not get a lot of call for that on peoples logs. It seemed they always want me slab the whole logs. I am starting to process differently now, some people are asking for just lumber. I use to saw and  leave and rarely see what the wood looks like years later.  It wasn't untill the kiln that I am able to see how the wood ends up. Now I get to see what I sawed a few years ago as people bring me their wood to dry.
 I am just starting on purchasing good hardwood logs for myself to process.