iDRY Vacuum Kilns

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Conditioning Phase of Drying Cycle

Started by Downhill Cutter, August 19, 2019, 08:26:08 PM

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scsmith42

Quote from: xlogger on October 30, 2019, 05:32:35 PM
So with large live edge slabs that have been air drying for months you unstack part of them to put in pins? Lots of work there.
With a Kil-mo-trol, yes. Usually we call pivot a board out of the side of the stack, insert pins and cable and then slip it back in. 
This method won't work with wide slabs though.
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

xlogger

So Scott I know you do more slabs than me, how do you keep track of MC when drying? If I understood Danny correct he does it about the same way I do. Correct me Danny if I'm wrong.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

WDH

Here is my method.  Air dry the slabs first to below 20%.  Target is 15%.  Put in kiln and set wet bulb at 120 and dry bulb at 75 so that the compressor runs full out.  Watch the water in the bucket.  At the start, I will get 9 gallons of water (Nyle L53).  As a few days goes by, less water per day.  After about 7 days (depending on species, oak takes longest), there will be only a little water in the bucket after a 12 hour period.  I know that I am getting close.  When I am down to about 1/2 cup or so and things seem at a steady state, I check the moisture content with the Delmhorst J2000X with the long insulated pins and the slide hammer.  If the moisture content is 9% or less, I close up the vents, shut off the compressor, and set the dry bulb temp to 150 degrees.  Once the temp hits 150 degrees, I run the kiln like that for 24 hours, then I am done. 

If I am still above 9% when there is minimal water in the bucket, i.e. the load seems to have stalled, I close the vents, shut off the compressor, ramp the temp to 150 degrees.  When I hit 150 degrees, I open the kiln doors for about 3 or 4 minutes to dump any water vapor.  Then run for another 8 - 10 hours and repeat with the doors open for about 4 minutes.  When I get below 9% moisture content, I hold the temp at 150 degrees for one more 24 hour period, then I am done.  That glides me in to 8%, my target here in Georgia.

My method involves a little science and a lot more experience.  Since I capture every drop of water exiting the kiln, I know when the compressor has done its job and it is time to check the final moisture content.  I also know whether it is time to sterilize or if I need to turn off the compressor and use higher temperatures to coax that last little bit of moisture from the wood. 

Since I can only do one thing at a time (do everything alone without any supplemental help), usually the load sits in the kiln after I am done and have shut everything off with the vents still closed and the kiln bottled up for another 24 hours, giving the load time to relax and equilibrate and I have time to unload and process the wood.  I do not unload the wood until I start planing  it and get it racked in the climate controlled space.  The worst thing for me is to unload the kiln but not be able to process the wood until some time later.  I learned that the priority is to process and rack the wood in a timely manner after it leaves the kiln.  If the outside humidity is high (usually is :)) and I let the wood sit under the shed for a while, the boards most exposed on the outside can gain moisture and bow a little, and I despise that.  All boards must be flat without any twist or cup. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

scsmith42

Quote from: xlogger on October 31, 2019, 04:39:54 AM
So Scott I know you do more slabs than me, how do you keep track of MC when drying? If I understood Danny correct he does it about the same way I do. Correct me Danny if I'm wrong.
My method is similar to Danny's, except that I use solar kilns as pre-driers (and for some species they will dry all the way).  In the Nyle, I'll set the temp at 150 and the RH% at 30% or so.  Once the load is done I'll crank up the RH% with the misting system for conditioning - starting while the load is still warm and I've turned off the DH unit.  I'll bring it up to 40% RH and then shut the misting system down.  
As the temp drops the RH% may increase a bit, but since the lumber is absorbing the moisture it usually stays pretty close to the 40% target.  I'll let the load sit for 24 hours sealed up before unloading.
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

YellowHammer

I use little bit of both techniques, air dry, then for wood that I know will stall, like walnut, I'll put it in the solar kiln, then finish it in one of the Nyles.

I do the sterilization to 150F, vents closed, compressor off.  Then I left it "rest" for 24 hours, put it in the warehouse, and let it sit with stickers and weight until is gets dead stacked a few days later.


YellowHammerisms:

Take steps to save steps.

If it won't roll, its not a log; it's still a tree.  Sawmills cut logs, not trees.

Kiln drying wood: When the cookies are burned, they're burned, and you can't fix them.

Sawing is fun for the first couple million boards.

Be smarter than the sawdust

Nebraska

Thank you all for the time and the knowledge. Learn something new everyday, so the day isn't wasted. Enjoyed the read.

xlogger

ok I'm pretty similar with you guys on that. Biggest question is how do you check you MC on slabs while drying? I usually don't even try checking till I see no water dripping and check with slide hammer on bark edges and try to find a place where bark has come off.  
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

WDH

I go in the side like you do.  As deep as the pins will go without the bottom touching the wood. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

YellowHammer

I go in from about a half a dozen places, on different slabs, in places the customer won't see.  I'd rather punch a few extra holes than find out after it's been pulled from the kiln.  

Another way to confirm the slabs are dry is to feel the air in the kiln after the load has been sitting for its rest period.  If the door opens and it's dry, that's a good sign.  If the air is slightly moist, that's not a good sign and time to start slide hammering to find out what's wrong.  

The true test of a whether a slab is dry is to lift it, and feel it.  After deadstacking a few thousand slabs, you'll be able to just "feel" if it's right or not.  If it's dry on the outside and wet on the inside, the little alarm bell in my head will know it and I'll start trying to find out what the problem is.  After all, if it's dry, it's dry, and dry doesn't weigh as much as not dry.  It won't have a slightly clammy feel, and the grain will have a collapsed look.       Sometimes a wet slab spot will even sound different when it gets deadstacked and dropped on the pile.  All are subtle clues something isn't right.  Look and listen for them. 

 
 
YellowHammerisms:

Take steps to save steps.

If it won't roll, its not a log; it's still a tree.  Sawmills cut logs, not trees.

Kiln drying wood: When the cookies are burned, they're burned, and you can't fix them.

Sawing is fun for the first couple million boards.

Be smarter than the sawdust

Stephen1

Quote from: WDH on November 01, 2019, 06:49:54 AM
I go in the side like you do.  As deep as the pins will go without the bottom touching the wood.
You do not allow that little washer gaurd to touch the wood?
IDRY Vacum Kiln, LT40HDWide, BMS250 sharpener/setter 742b Bobcat, TCM forklift, Sthil 026,038, 461. 1952 TEA Fergusan Tractor

GeneWengert-WoodDoc

The small washers are used to prevent electrical contact of the probe itself with the wood. When using washers on both needles, it is ok to drive the needles all the way in.  However, the extra 1/8" will not make any difference.  Plus, if the needles break, having the extra 1/8 inch, when not driving all the way, to grab on with a vice grip is really helpful.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

moodnacreek

While I have nothing to add to this as I do not have a kiln, I find these posts very interesting.  At my sawmill air drying has been the only way for a long time. What I have learned is that some woods will not really air dry on sticks, out doors or even in sheds. Elm and hickory are bad and w. oak all goes for trailer planks, even clear stock.   To you kiln driers, keep up the good posts.

WDH

Quote from: Stephen1 on November 01, 2019, 08:10:39 AM
Quote from: WDH on November 01, 2019, 06:49:54 AM
I go in the side like you do.  As deep as the pins will go without the bottom touching the wood.
You do not allow that little washer gaurd to touch the wood?
No Sir. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

PA_Walnut

I am in the same camp with @YellowHammer and @WDH . Air dry it well, then put some heat to it until it stalls, then close'er up and put the heat to it. 

I have some 12/4 walnut slabs in right now that were about 20%. Some is down to 8-9% and other slabs/spot are 16-17%. Stalled out at 120°, so pushed it up to see what happens today. Once they are are down and closer, will run it up to 155° and shut all the vents. Sometimes I dump some water in too. I find that the added MC, evens things out and then I vent it and continue for 24 hours. 

With 50" crotch slabs in there, don't wanna ruin the load!  :o Maybe I need one of them new-fangled kiln things where I just push the big red button and magic occurs.  ;D :D



I own my own small piece of the world on an 8 acre plot on the side of a mountain with walnut, hickory, ash and spruce.
LT40HD Wide 35HP Diesel
Peterson Dedicated Wide Slabber
Kubota M62 Tractor/Backhoe
WoodMizer KD250 Kiln
Northland 800 Kiln

WDH

That red button thing is called a vacuum kiln ;D.
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

PA_Walnut

Quote from: WDH on November 26, 2019, 07:47:55 AMThat red button thing is called a vacuum kiln .


I know...being sarcastic. It's been dubbed the, "Devine Drying Device", replacing all knowledge gained over the past century or more. :D
I own my own small piece of the world on an 8 acre plot on the side of a mountain with walnut, hickory, ash and spruce.
LT40HD Wide 35HP Diesel
Peterson Dedicated Wide Slabber
Kubota M62 Tractor/Backhoe
WoodMizer KD250 Kiln
Northland 800 Kiln

Stephen1

Quote from: PA_Walnut on November 26, 2019, 06:33:13 AM
I am in the same camp with @YellowHammer and @WDH . Air dry it well, then put some heat to it until it stalls, then close'er up and put the heat to it.

I have some 12/4 walnut slabs in right now that were about 20%. Some is down to 8-9% and other slabs/spot are 16-17%. Stalled out at 120°, so pushed it up to see what happens today. Once they are are down and closer, will run it up to 155° and shut all the vents. Sometimes I dump some water in too. I find that the added MC, evens things out and then I vent it and continue for 24 hours.

With 50" crotch slabs in there, don't wanna ruin the load!  :o Maybe I need one of them new-fangled kiln things where I just push the big red button and magic occurs.  ;D :D




I'll let you know how the big red button works. #shelby78 dropped off 2 50" walnut slabs for me to dry. They just fit in the kiln. They are on the bottom of another load of 4/4 and 6/4 walnut and cherry. 

 

 
IDRY Vacum Kiln, LT40HDWide, BMS250 sharpener/setter 742b Bobcat, TCM forklift, Sthil 026,038, 461. 1952 TEA Fergusan Tractor

PC-Urban-Sawyer

Looks like the magic has already occurred. That's some beautiful slabs.

Stephen1

 

You can just see the edge of the 2 big walnut slabs .
That is my walnut/cherry and then another customers Cherry on top.
IDRY Vacum Kiln, LT40HDWide, BMS250 sharpener/setter 742b Bobcat, TCM forklift, Sthil 026,038, 461. 1952 TEA Fergusan Tractor

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