New Box Kiln - Drying Schedule Questions

[Terry Liberty]

Here's the situation: I just completed a box kiln with 1/2" OSB sides lined with 1", foil-coated foam board. Dimensions are 3x3x4 feet. At the moment I've tested it empty with a 250 watt heat bulb. The top is slid slightly off so there is a 3/4" x 4' slot opening at the top. There's a 6" x 8" opening at the bottom where the lamp sits. In the first test I was able to get it to 108 F, 26% RH. Ambient was 70 F, 53 % RH. I'm assuming this is a workable internal temp and RH but I'm not sure where to go from here. I have some 1" and 2" Big Leaf Maple (acer macrophylum) that's been air dried to 11-12%MC. I'd like to get it down to 8-9% but I have no idea what a good drying schedule would be.

Oh yeah, I have a "DuctStat" unit that I can use to regulate the temp inside but have not hooked it up yet.

Second question is: I have a General brand moisture meter with 1/2" pins. How helpful will this be in my process? I don't have enough wood to go whacking off a chunk every time I want to check progress.

Any thoughts on how to proceed?

[Danny Hamsley]

For maple that dry, running the kiln at that temp and relative humidity will be fine. You can dry if now as fast as your unit can pull the water out.

[Cody Colston]

In the first test I was able to get it to 108 F, 26% RH.

Second question is: I have a General brand moisture meter with 1/2" pins. How helpful will this be in my process? I don't have enough wood to go whacking off a chunk every time I want to check progress.

Any thoughts on how to proceed?

I agree with Danny. You can't hurt the wood now and the 108* at 26% RH will dry it to 8% pretty quickly.

The General moisture meter is OK for checking relative MC (ie, how much the MC changes) but it's not all that accurate, especially on the 8/4 stock. No pin meter is, really. I'd suggest you work the stock in stages when you are ready to use it. Rough cut it to length/width, thickness it to a bit over final dimension and then let it "settle" for a week or two (minimum) before bringing it to final dimension. That's assuming your shop is at a RH that is compatible with 8% MC.

[Mike Gresham]

That's assuming your shop is at a RH that is compatible with 8% MC.

That is something I have been wondering. What shop RH would be compatible with 8-9% MC?

[Cody Colston]

45% RH at 70 degrees f gives an equivalent 8.5% MC. I found the following site useful for converting RH to MC. http://www.csgnetwork.com/emctablecalc.html

[Mike Gresham]

45% RH at 70 degrees f gives an equivalent 8.5% MC. I found the following site useful for converting RH to MC. http://www.csgnetwork.com/emctablecalc.html

Good info Cody. Thanks.

[Terry Liberty]

Re: The original post---

Thanks folks for the info. I'll be trying the kiln out in the next day or two. Much obliged.

Terry