weighing down a pile

[Dan_Shade]

is there a standard for how much to weigh a pile down?  I've seen 100lb per square foot, and even up to 500 lbs per square foot.

for a stack 4' wide, and 8' long, here's a small chart I figured up:

Code Select Expand


Width      length area load               total weight on pile
feet feet sq. ft        lbs/sq foot   lbs
4 8 32 100 3200
4 8 32 200 6400
4 8 32 300 9600
4 8 32 400 12800
4 8 32 500 16000


that's a lot of weight, am I missing something?

[Paschale]

I've not used nearly that kind of weight to hold the lumber I've air dried down.  I mean...as I'm thinking about it, for the upper middle to bottom layers, you've got the weight of all that wood above holding things down, so all you really have to worry about is the top layers.  From the books that I've read, there isn't a specific weight per square foot, but rather "just enough weight to keep it from warping."  I guess that's open to interpretation.  But quoting here from THE CONVERSION AND SEASONING OF WOOD, by William H. Brown, he says this in a section regarding air-drying, "The simplest form of cover to use is a sheet of heavy duty polythene placed under the top layer of boards or, if the latter are also to be protected, on top of the pile with something like old timber to weight it down." 

In the the Fine Woodworking book WOOD AND HOW TO DRY IT, they just suggest putting cinder blocks on a top layer of plywood, scattered across the top.  I can't imagine you'd need 16,000 lbs to have sufficient weight...it just seems a little overkill.  Just so long as those top layers aren't warping...that's enough weight, whatever that may be.

Makes you wonder though...   :P

[Dan_Shade]

I typically put about 400lbs on top of a 4x8 pile, but digging around, and seeing the 100lb/sq ft, I was like wow, i'm not even close to that...

the other side, is I sure don't want to lug 3200lbs ontop of the pile after a long day of sawing!

[scottr]

Dan , you want the boards to be able to shrink in width as they dry . Try six cement blocks on top of your 4' by 8' pile .

[Dan_Shade]

I can't see how only 6 blocks on the top of the pile can be enough to keep the wood from cupping...

[scottr]

Dan , on page 82 & 83 in your Wood and How to Dry it book the illustration shows a 4' by 8' stack with a sheet of plywood and two cement blocks on top .

[DanG]

Just because it's in the book don't mean it'll work.  Two cinder blocks would barely keep the plywood from blowing away. :D :D :D

[Brad_S.]

I use a few railroad rails placed on stickers on the top of the stack in my kiln. Was a cheap and easy way to add weight but since scrap steel prices spiked, it may not be cheap, but it's still easy.

[Tom]

Doesn't this stretched out page make it fun to post?

I still favor an Abrahms Tank parked on top for weight.

I've seen an oak board that wanted to move, raise the whole stack.

There is a lot of strength in a board that wants to warp.

[Part_Timer]

I use about 20 blocks with the holes filled with concrete. 

I also have a bunch of 1 gallon paint cans with lead in them.  When I need to melt more bullets I loose a can or 2.  fill a couple more blocks. 

If I have a stack with a bunch of tension I ratchet strap it first then weight it.  No way I'm keeping 3200 lbs of weights around.  My back is not that strong ;D ;D ;D

[Dan_Shade]

page stretched?

sorry about that, i was trying to make a nice neat table :(  it works fine on my monitor.  I"ll edit out the metric stuff

Hope it works a bit better for you guys now...

for my weight, I typically use those green plastic planters, the 24" ones, I can get half a bag of 80lb concrete mix in one, which leads me to 80 lbs on top of each sticker, I guess i'm going to have to get a bunch more of the planters, I don't see me getting 3200 lbs, but I may double the weight on it, I'm afraid of crushing the wood fibers if I put too much weight on it.  is this possible?

[Rockn H]

  No way I'm keeping 3200 lbs of weights around.  My back is not that strong ;D ;D ;D

Sure you've got that much weight and you don't have to lift it.  The first time I read 3200lbs of weight I pictured just driving a medium sized car , say a 4 door Chevy Caprice, up on a stack of lumber.   Seriously though, I've always just put enough weight on top to hold the tin down.  If I think a stack may move I'll put a few 2" ratchet straps on it.

[Don_Lewis]

I know one guy that uses water bed mattresses.

[Tom]

That actually sounds like it could be a pretty good idea, Don.

[Larry]

Excellent idea Don.  I used to use big patio blocks but it is just plain hard labor getting em up there and you need couple of tons to do any good.

Electric Al posted a picture long time ago where they were using about a 4" thick concrete slab on top of the lumber.  Betcha he was using a machine to put the slab on top or made Linda lift it up there. ;D :D ;D

[OneWithWood]

Does weight actually prevent wood from moving?  It seems to me that all that weight simply delays the movement.  Once the weight is removed won't the forces involved cause movement shortly thereafter?

[Tom]

I've not found the stuff to move much once dry.  If it gets wet again, then all bets are off.

Not knowing a better word, wet wood develops a "set" as it dries.   If you bend a piece of wood and hold it bent until it dries, it will retain a lot of the bend.  I think the same is true for holding it straight.

[OneWithWood]

OK.  Do you have a spare Abrams I could have?  Mmmm, I think I had better make my kiln chamber bigger to accomodate my top weight  :D

[Tom]

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? :D

I still like the idea of the Abrahms too.  It would be dual purpose in that I could use it to move idiots, like double parkers, out of the way when go to town. ;D

[red]

you just dont want to make that pile to high 


i would hate to have to jump/climb onto that bed for a quick snooze

maybe a few waterbeds at different heights around the yard might work

one for the dog ...customer waiting area

[Furby]

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

[Tom]

Kiln??      :D :D

[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. ;D 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.