Mixed charges

OneWithWood · July 13, 2006, 11:06:11 AM

I sized my kiln for 3,000 bd ft charges. Now I wish I had built a somewhat smaller kiln for those times when I want to dry smaller quantities. My solution is to dry mixed charges where feasible. I have researched this somewhat :P and came up with this breakdown of woods that I can mix without disasterous results.
Please comment on my groupings. Am I out to lunch? :

      Drying Schedules 4/4

Species      Dry-bulb Temp   Wet-bulb Temp
Oak, white   T4      C2

Oak, red      T4      D2

Elm, Rock      T6      B3

Sycamore      T6      D2
Elm, American   T6      D4
Walnut, black   T6      D4

Ash, green,white   T8      B4
Cherry, black   T8      B4

Beech      T8      C2
Maple, sugar (hard)   T8      C3
Sweetgun (red gum)T8      C4

Hickory      T8      D3
Ash, black      T8      D4
Maple, red, silver   T8      D4
Sassafrass   T8      D4

Butternut      T10      E4

Yellow poplar   T11      D4

Blackgum      T12      E5
Tupelo, black   T12      E5
Aspen      T12      E7
Basswood   T12      E7

Sweetgum(sap gum)T12      F5

Am I on the right track?

All this lined up and made sense when I typed it but I see it gets a bit muddled when posted. The groups are separated by a space. For example WO is a group by itself as is RO and Elm. Then Sycamore, American Elm and Walnut are a grouping that might be mixed in a charge without serious defect. The T number is a representation of max dry bulb temperature. The A-F numbers represent moisture gradients or wet bulb temps.

Ga_Boy · July 14, 2006, 09:35:18 AM

OWW,

To really make sense of what you are doing we need the Starting Temps and RH.

I mix species that are within 30-40 degrees of starting Temp and 10-15% or so of starting RH.

Please note that I use a RH sensor, this means I do not do the Wet Bulb/Dry Bulb stuff. But most schedules have the RH listed.

For example I mix Yellow Poplar and Holly with excellent result. I use the Poplar schedule and push it hard to compress time for the Holly.

Let me know if this does not make any sense and I will IM you with my cell number and we can shoot the bull abuot this.

Mark

Don_Lewis · July 18, 2006, 07:27:31 AM

That is a pretty good approach.

If the wood is all below 25% all the way through, mixing species is not a problem but you would want to run equalization conditions and not a schedule. That is you would set conditions that give you the EMC you are shooting for rather that the schedule which will often have EMCs that are too low and the faster drying pieces will overdry.

The other concern is drying rate. The schedules don't take into account how long it takes to get from, for example, 40% to 35%. So you want to group green lumber by drying rate. This is why many people mix Red and White Oak successfully. White Oak loese less water per day but usually starts with lower initial moisture content

OneWithWood · July 18, 2006, 08:40:53 AM

Thanks, Mark and Don. Where would I find the drying rates of various woods?

TexasTimbers · May 09, 2007, 01:35:55 PM

I'm bumping this because I would like an answer to OWWs question. Where would I find drying rates of various woods? Maybe that government dry kiln tome. I have it "somewhere".

I searched the archives and found this thread, but would still like to ask if y'all think it would be allright to mix in a small batch of Honey Locust with some Black Walnut. I am told BW is quite forgiving when it comes to drying. Don't know about HL.
Both speices were cut early this year - the slabs knocked off then, and now are fixin to go on the Woodmizer for resaw into 4/4 to be taken down to 3/4 wide plank flooring.

Den Socling · May 12, 2007, 08:39:08 AM

Agriculture handbook #528 written by Gene Wengert and John McMillen has a list of drying times for 4/4 hardwood. You could add to that the beginning moisture content which can vary from 40% to 100% and make a chart of acceptable drying rates.

BTW Gene spent last Monday afternoon here and I met a man I didn't expect after various experiences at that other forest forum. After discussing modern vacuum kilns, we had a pleasant dinner. It certainly was not the meeting I would have expected a couple years ago.

TexasTimbers · May 12, 2007, 09:12:38 AM

I have always been of the opinion that he is a good man based on how he runs his forum. I traded a couple emails with him about drying last year, and although he suggested poting the questions on the forum he was very gracious and forthcoming.

I have had nothing but good experiences with him. Would like to meet him someday as well.

I'll do what you said Den but I bet I will have more questions as I start. ;D

scsmith42 · May 12, 2007, 10:09:29 PM

Kevin, in addition to the USDA manual, Nyle provides daily MC% reduction information with their DH kilns.

Scott

Jeff · May 14, 2007, 08:12:14 PM

Thats cool Den. Dr. Wengert registered for the Forum a week or so ago. He has not logged in as yet, but maybe at some point he will join in.

I suspect we might get to meet at SAWLEX. I hope so.

Den Socling · May 15, 2007, 05:10:54 PM

Hi Jeff,

I expect that he will be joining some discussions but he was on his way to New Orleans to start a bike ride to St Louis or some crazy bike ride like that. :D He had his bike in the back seat!

Den

TexasTimbers · May 16, 2007, 07:56:40 AM

Oh! A biker type eh? Whooda thunk it. :D

BBTom · June 04, 2007, 07:17:13 AM

Attached is a grouping chart that I came up with some time back for mixed loads. As long as you keep in the same group, you are fine. Mixing group numbers is more dicey. This excel file also has all my kiln schedules in it. Let me know if you find any problems.

TexasTimbers · June 04, 2007, 01:13:37 PM

Don't suppose you have it in a pdf?

BBTom · June 04, 2007, 06:10:06 PM

Sorry Kevjay,

I don't have Openoffice on this computer. If anyone has it I think they can open an excel file and save as pdf. I know some forum members use Openoffice, so maybe one of them could do that and post it. You could get Openoffice and then you could see the excel files. It is a freeware program available at openoffice.org

TexasTimbers · June 04, 2007, 06:40:17 PM

I tried to download openoffice several times over the last couple weeks when I have had time to babysit the computer and have had failures of some sort everytime.
Guess I will have to spend the big bucks for Windows Office. I lost it all when my puter crashed. :(

Ianab · June 04, 2007, 07:21:35 PM

Quote from: kevjay on June 04, 2007, 06:40:17 PM
I tried to download openoffice several times over the last couple weeks when I have had time to babysit the computer and have had failures of some sort everytime.
Guess I will have to spend the big bucks for Windows Office. I lost it all when my puter crashed. :(

Someone must have a copy they can send you on CD?
I could, but the airmail would be an arm and a leg for 'free' software :(
It just goes against my principles to have ya spend money on MS Office when you dont need to ;)

Cheers

Ian

TexasTimbers · June 05, 2007, 09:51:56 AM

Quote from: Ianab on June 04, 2007, 07:21:35 PM
It just goes against my principles to have ya spend money on MS Office when you dont need to ;)

Me too. I just ordered the CDs off of Amazon. Cost $14 after shipping, but beats the heck out of hundreds of bucks that would help fund Gates' charities - which run all over the map.