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Author Topic: doug fir 4 inch mc & skip  (Read 4414 times)

Offline wayne cunliff

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doug fir 4 inch mc & skip
« on: December 14, 2011, 02:25:14 PM »
So we have a wagner inline moisture meeter drop out system at the planer which by the way works awsome. But i cant use it on my four inch DF becasue core of the wood is wetter then the shell and it is my understanding that you can not dry the entire piece down to 17% with out skip, i dry the shell down to 17% and it looks good going thru the planer but im haveing a hard time getting all of it down with out over drying it. any ideas

Offline MichaelM

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Re: doug fir 4 inch mc & skip
« Reply #1 on: December 14, 2011, 05:00:35 PM »
Hi Wayne,

Shrinkage is mainly a function of final MC.  If a lot of skip is occurring and the wood is not over dry, then the rough green target size is too small.

I don't know what your drying time is or your quality requirements.  Uniform MC and less overdry can be obtained by drying more slowly and/or decreasing the wet-bulb depression toward the end of the schedule.  There's not enough information to answer more.

Mike M.

Joe D

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Re: doug fir 4 inch mc & skip
« Reply #2 on: December 16, 2011, 09:48:34 AM »
A couple questions:
1.) What type of drying schedule are you running? And how much time pressure do you have drying it?

2.) What moisture content standards does it need to meet?

3.) Is a high or low grade product?

Offline wayne cunliff

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Re: doug fir 4 inch mc & skip
« Reply #3 on: December 19, 2011, 03:07:01 PM »
The rough green target is 3 3/4 x3 3/4 for 4x4 and the 4x6 is 3 3/4 x5 3/4 it is premmium exposed i was drying it in seven days or 5 with the last two EQ and moisture 21 and under so it dont mold but above 17% so theres no skip ill try to attach the schedule for ya iv only dryed it four times and i dont like it cause iv been relying on the inline moisture system to get my data and i cant with this product any ways iv got another charge of it comeing up so hopefully i can get some tips.   P.S For any body from wagner that reads this i am by no means bashing on are inline system it works awsome.

Joe D

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Re: doug fir 4 inch mc & skip
« Reply #4 on: December 21, 2011, 05:24:31 AM »
Thank you.

Please excuse and correct me as I make some comments.

You said you dry this material in five days with an additional two days of equalizing and condtioning. Your schedule looks like a mild conventional schedule. If I'm reading it correctly your schedule runs 324 hours plus equalizing and conditioning. If you follow your schedule at 120 hours, five days, you are at approximately 160DB and 140WB with an EMC of 7.9%. In my mind this is a good mild way to proceed. With what you stated I assume at 120 hours you go into equalizing, 155DB and 150WB with an EMC of 15.2, and then a conditioning cycle.

If I'm interpreting this correctly all of the lumber has not had a chance to dry. And probably stops drying during the equalization and conditioning phase. So if you are limitedd to a seven day drying cycle, and you are experiencing wet lumber I would skip the equalization and conditioning phases and continue to dry the last two days. To chck this assumption with your current operating procedures check the MC of the lumber in the kiln just prior to equalizing and conditioning. To not overdry I would limit my maximum wet bulb depression to 20 degrees (the difference between the dry bulb and wet bulb temperatures). This will keep the EMC at 8%, which should limit the overdrying. If you follow this advice I would check the moisture of the lumber with in the kiln with a moisture meter at the morning of the fifth, sixth and seventh day and note the average and standard deviation of the lumber in the kiln versus what you find in the planner mill.

Let me know if I make sense, give me your feedback.

 


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