Random length boards in kiln

JoshNZ · July 02, 2022, 06:21:45 PM

What is the best way to load say a 20ft kiln with 12-15ft boards? No doubt the best answer is to only saw 10 or 20ft long boards but when you don't have that luxury...

The only way I've thought of so far is to butt boards up to each end alternating, and overlap them like finger joints in the middle, but this of course leaves a stack with boards missing from each layer at each end, and an area in the middle with no boards missing.

Is there an easier way?

KenMac · July 02, 2022, 09:14:28 PM

Certainly not the expert you're probably looking for, but I try to stack longer boards on bottom and shorter ones on top. If that's not practical, I would proceed as you mentioned, trying to get all ends landing near a sticker.

YellowHammer · July 02, 2022, 10:02:54 PM

The key is to load them all so that their ends are supported so as not to cause stack bow and end droop. So I agree, stack the boards with the longest on the bottom, and the ends all flush on one side, and the short ends landing on stickers, even if you need to double up on stickers on that side. I also will "save" space on the back of the stack for stacking full length there so the odd long one has a place to stay. So the stack is kind of three dimensional, full length on the back, full length and half pyramid shaped to the top, so as not to have to play too much with the boards as they are stickered. Little shorties are added to the half shorties to get full length. This also makes baffling the ends easier.

JoshNZ · July 03, 2022, 05:55:10 AM

How do you baffle the end of a stack that is shaped like a pyramid then? You need to cut a sheet of ply or something to match it each time?

KenMac · July 03, 2022, 03:32:21 PM

My stacks are seldom very pretty as far as ends all being even. I use plywood or similar to fill in areas that are open after baffling. Short sheet metal screws hold everything in place well enough.

caveman · July 03, 2022, 05:50:57 PM

We use tarps and soccer mom tents held in place with spring clamps.

YellowHammer · July 03, 2022, 06:03:59 PM

I use foam board and I don't baffle as much as I used to. Remember as the wood gets more dry, the effect of wind velocity decreases influencing the drying rate, so baffling is of reduced importance the more dry the wood gets. Since I generally dry wood that has been air drying for a few weeks, and is in the 20% to 30% range, tight baffling isn't as important, especially if I can increase the airflow simply by using a little more fan flow.

Sod saw · July 05, 2022, 01:09:24 PM

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YH,

Doesn't the air flow (or lack of) affect the ability of the heat to reach "all" of the board surfaces during the sterilization part of the drying process?

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YellowHammer · July 05, 2022, 03:02:36 PM

No, not really. There will always be some forced airflow through the stacks because there are lots of fans, all spaced evenly down the chamber and even though some air will cheat around the edges of the pack, it's not much. The key is to try to get one level layer on top for the top baffle, so that's why I try to have at least one full length layer full height.

The airflow through the pack is easy to check by dropping a little sawdust on the outflow side of the packs, and if you can see it move a little due to airflow, things are good.

As long as there is some circulation then there will be enough provide conductive heating to the wood in all the layers. Also, I sterilize for 24 hours, so even the smallest amount of airflow is adequate.

The more dry the wood, the less positive effect baffling provides, either good or bad. So wet wood gets lots of baffling, dry wood, not so much.

Sod saw · July 06, 2022, 09:33:22 PM

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YH,

Thanks for the explanation.

I specially like the saw dust trick. It seems less stinky than smoke or incense, like we used to use to check window & door leaks in homes.

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