weighing down a pile

[Furby]

How would the temp of the water in the bed affect the operation of the kiln?

[Tom]

Kiln??     

[Furby]

[SwampDonkey]

I find yellow birch is bad for twisting as it dries. My piles are relatively small (depth-wise) and I don't weight it down. Them warped peices just get used to make small items. Once in awhile I'll get a butternut warp like a bow, well that is either a tree that leaned hard or most likely someone thought they could make use of a limb. 

[OneWithWood]

How would the temp of the water in the bed affect the operation of the kiln?

Well, if the temp is just right I might not wake up in a timely fashion to start up the kiln.  So I would have to say the temp is critical to timely drying.

[Furby]

 
Good answer!

[DanG]

The waterbed ain't a bad idea, but it takes up a lot of space that could be used for drying/storing firewood.

[Randy]

Ok Guys all this weight is hurting my back. Why not do this--------say you have stacks that are 4ft wide by 8ft long---------Why not get 6-5ft wide brick lintel's------they are strong and not real heavy---Or you could probably use some 4x6 or bigger dried oak-----make a clamp by adding chain to each outer end of the bottom piece's and a large turn-buckle with a hook on the bottom to the top pieces or you could use chain binders. Slide the piece under the pile----lay the other piece on top--------take the chain and hook in onto the hook end of the turn buckle---tighten. Check them every few days-----re-tighten when needed. Would cost a little to get set-up, but would save your back and last for years. Adapt to fit your situation. Randy

[Part_Timer]

Randy we been thinking along those lines.  We were going to use painted unistrut and all thread in the kiln.  Just run the all thread through the slots in the strut.  Tighten down and check every few days. Should alow me to stack another 4 rows in it..  We'll see on the next load 

[Tom]

Checking every few days isn't going to do you much good.  That's why straps are so difficult to manage.  If a board is going to move, it will move when your back is turned. 

There is another disadvantage to too much weight on top.  you can actually crush the fibers in the boards on the bottom.  Take into consideration the amount of weight that is on a sticker on the bottom of the pile.  Then think of what you do to it by parking that Abrahms on the stack.

You will seldom see large weights on the top of stacks on commercial drying yards.  The stacks are covered and enough weight to keep the cover from flying off in the wind.   A lot of board movement can be curtailed by air drying in drying sheds rather than in the open.   If the stacks are narrow and tall, the number of boards that move because of no weight is minimal.

[ellmoe]

We use nylon straps and weights on top. The weights are peices of scrap metal, old pillow block bearings, big gears , etc.. We cross the bundle with 1x4's over each stick and stack one layer of weights on each 1x4. The nylon straps are pulled as tight as possible as they will loosen as the wood shrinks. I imagine each 8' bundle has 300-500 lbs on it. You are really trying to contol the top layers as the weight of the wood contols the lower. The straps help control during the initial drying and help control side-bending in the boards. If we can get in the kiln to tighten the straps during drying I will do so. Usually, the kiln is loaded such that I can't fit between the wood and the door.
Mark

[Ironwood]

I have 10" I beams under the floor of my moveable kiln. I welded 1" nuts to those and then threaded LARGE eye bolts in to those, I beleive there are four in the front and four to the rear. I sealed around the threads to prevent water seepage. I do trip on them occasionally when it's empty. Should I ever need to strap a load in to prevent warping, there you go to heck with all that tonnage talk. My back hurts just loading the wood! Also the eyebolts enable me to chain the main frame of the kiln to my 8000lb forklift mast to move it as no forks are long enough to fit to the back of the kiln.

                                             REID

[t_andersen]

That's what makes Don's suggestion so viable.  You could put a flat surface on the stack and then put an empty water-bed mattress up there and fill it when it's up there.  Pretty ingenious, eh?

that is.... unless it leaks!

[Riles]

I think you have to look at the math again. 100 lbs/sq ft across an entire 4 X 8 sheet is alot of weight. But if there's a row of stickers between the top pieces of lumber and the covering sheet of plywood, you need only center the weight on the stickers. 100 lbs/sq ft is 0.694 lbs/sq inch and on a sticker 4 feet long and 1.5 inches wide, you only need 50 pounds of weight along each sticker. Five rows of stickers is 250 pounds of weight and that sounds a lot closer to what people actually do.

Since you're keeping the lower layers of lumber straight with stickers, it makes sense that it would work for the top layer as well. The lower layers are certainly getting more weight (as well as being better distributed along the sticker).

Now if you could just find 4 foot long, 1.5 inch square stickers that weighed 50 pounds, you could leave the water bed back with the orange shag carpet and the lava lights.

[jimF]

I think you are looking at the problem from the wrong direction.  You could put enough weight on top to keep it from warping, but it would crush the wood under the stickers.
The problem of warping is either some abnormal grain in some cases but most of the time it is caused by too slow of drying.  The three positions that warp is observed most is: 1) in a very slow drying kiln setting (too high of RH), 2) where the air flow is blocked (like where some plywood is nailed in place to direct the air flow away from a spce between two piles or two stacks where the spacing does not line up vertically) and 3) at the top of the stack.  Because of most airflow arrangments ( baffles and decking separating the heating area from the stack) the airflow can be almost zero on top of the stack.  All these cause too slow of drying.
Even with abnormal grain, speeding up the drying will reduce warp.