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Nyle L53 Kiln Start Up

Started by maderahardwoods, November 13, 2017, 03:27:39 PM

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maderahardwoods

UPDATE: Looks like it was a fluke, I went into the kiln to see if the coil was cold and noticed the wick on the WB thermometer was withered.  I cut a piece of wick and made sure it was wet. 

The WB then dropped to the 80's where it was.  The wood does not have that wet cool feeling fresh wood has, I am dying to get my J2000x.

WDH

My money says that you are there. 
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'm worried maybe a little too dry.
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

maderahardwoods

I hope not, the wood did not look any more stressed than usual (same checking).  I cut power to kiln completely last night to allow the wood to slowly come back to ambient. 

maderahardwoods

UPDATE: The wood is definitely not dry.  I opened up the kiln and everything looked and felt great on the surface.   

I decided to cut the last 6" off of the top slab to take a look inside the slab...I took the cut and could feet that the end grain was wet, it had a cool feel to it.

I took the chunk home and split it in half and feel the water sprinkling on my hand, the freshly cut surface felt similar to a freshly milled slab.

Not really sure how to proceed, I have read that claro walnut could be difficult. 

Any input is appreciated, I may try and give another mill a call and see if they have any advice. 

Thanks,

Marco


YellowHammer

That's crazy.  What is the WB/DB now?


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

boardmaker

I skimmed this post pretty quickly, but it looks like you still haven't done an oven test.  Correct?

maderahardwoods

I actually powered off the kiln completely, before then the DB was 120-122 and the WB was in the mid-80s. 

I should have my Delmhorst this evening, I have not done an oven dry test.  But I may try it today if I can borrow a precision scale from my brother. 

maderahardwoods

Where do I begin....

I got the delmhost and went over to the kiln to take some readings.  I started with the top slab on the short stack, it varied from 13-15%.

The slab underneath it read anywhere from 45-50%.  The large slab varied from 45% to 12% on the far end. 

So I decided to ask a few sawyers/kiln operators who strictly deal with live edge slabs,  a gentleman in Minnesota was very friendly and willing to share some tips with me, I will share what he told me with you.  It was somewhat hard to hear him with our connection, so I may amend this information in the future. 

If you want the sap wood to really "pop", allow the slabs to sit in the sun for 1 day per side to oxidize
Use and electric planer to plane the sapwood 1/64 below the heart wood
Coat the heartwood with a 50% mix of Anchorseal and water.

He told me the slab drying process is not like the board drying process and that it is much much longer.  He allows the boards to air dry until they reach 25% (need to re-verify). 

Once in the kiln for final dry he said it is normal for the compressor to rarely come on, the wood will sit at 120F and slowly draw the water from the center.  The moist air escapes from the imperfections in the kiln, but he said occasionally the compressor will come on if the WB hits the set point of 95.  He follows this process until dry. 

WDH

I also pre-dry my 9/4 slabs under the air drying shed until the moisture content falls below 20%.  I do not have any problems getting them under 10% in about 10 days in the kiln with the DB at 120 and the WB at 75.  I have never attempted to dry them green in the kiln.
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 also typically air dry my walnut slabs for months before I DH kiln them as it doesn't make sense to commit the excess kiln time to dry green.  I have a specific building dedicated for air drying slabs.  However, I have also dried them (walnut) in the kiln with only a few weeks in the air drying shed when I really need some out.  I also use my solar kiln, and will dry pretty much every species from green in there, takes several months, then finish them in the L53.  I regularly dry 9/4 poplar, basswood, pine, soft maple from near green in the L53.  In these cases I will flash off the surface moisture with blowers to prevent sticker staining.  I have also experimented and slipped a few pieces of 9/4 walnut into my 4/4 stack as an experiment in my L53.  The 4/4 acted as ballast and prevented the 9/4 from drying too fast.

Its very important to know the species' drying behavior, max moisture removal rate, etc.  I've never dried Claro Walnut, but Appalachian Black Walnut can tolerate 8% moisture loss per day, 4/4, so probably 4% for 8/4, and its pretty hard to get that rate with a DH kiln, so I've had success with it.  The kiln generally can't remove moisture faster than walnut can tolerate, especially at the lower MC's.  I don't use long probes with thick walnut, the oven dry method is the best, surest way to to see how the core is drying in relation to the case, as demonstrated in this case.  I will stick the case with the Delmhorst to see what the case MC is, and compare it to oven dry for overall results. 

I've never heard of the the techniques described using a hand planer.  Seems like he has a system that works for him.  It seems counterproductive to seal the heartwood, which is where the wet pockets would be most prone to stall.  Why seal the wood to protect from excess moisture removal when that is the very problem, i.e. moisture removal is too slow.  Again, its important to know the characteristics of Claro to develop or optimize a strategy specific to it.  There may be some historical literature on the subject.

One thing that jumps out at me is that your top slab was 30% dryer than the slab underneath.  This is a very important clue.  Why did this happen?  What was different about it?  Heartwood/sapwpood ratio, thickness, etc?  What about the kiln geometry?  Typically, a differential drying on the top layers my DH kilns indicates more airflow and more exposure to the airflow to transport moisture.  I typically see this on the top layer if it is fully exposed to the airflow.  Normally, I cover my top layer with a light canvas tarp to restrict excess airldfow across it.  In your case, it might indicate that the airflow across the top was more optimized.  Were there defects in the top slab indicating excess drying rate?  The effect of airflow/velocity is well know, and it is proportional to the moisture content of the wood.  The higher the airflow and the higher the moisture content of the wood, then the more moisture will be removed.  As the wood dries, the moisture removal rate decreases.  Thats why many folks, like myself and WDH use air drying sheds as the fans will remove moisture as fast as the wood can tolerate, without tying up the kiln.  So I would say, without more information or a clearer visualization, that there is as airflow issue which caused the top layer to dry faster than the other layers.  It could be the baffling or a stagnant airflow through the pack.  In addition to the two fans in the L53, I have added 4 fans to the horizontal baffle, and cut another intake on the bottom of the kiln, to blow out any dead spots.  I have a total of 6 fans across the length of the baffle.  I used an anemometer to measure airflow though the layers to make sure it is consistent and uniform when I first setup the kiln and to make sure my baffling was effective.  Where is your baffling?  On top, sides, bottom?  The top slab behaved more like what I would have expected.  If the top layer was only one slab, it may be the properties of that particular piece of wood, if it was two slabs, then its a kiln condition issue.  The information that there is such large differences in moisture across the length of the second slab also indicates an airflow problem. However, it would be useful to understand where the wet and dry areas were in the wood.

Some detective work is in order.  That's what makes kiln drying interesting.   
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

maderahardwoods

Yellowhammer and WDH thank you for the excellent responses and information, you have really help keep me grounded.  There aren't a lot of sawyers let alone kiln operators in my neck of the woods. 

I was a little nervous about placing such freshly milled boards in the kiln for drying, but Stan a Nyle mentioned many people place freshly milled slabs in the kiln to fully control the drying process.  I understand it isn't the most efficient, but I really need to get my first load out to have product to move.

I am currently air drying all of the slabs I have milled under the shade of a large orange tree out of direct sunlight. All slabs are placed on leveled cants and are ratchet strapped down to keep the slabs flat. I will be purchasing some mesh tarps to keep any debris of them, and when it does rain I will cover them fully with a tarp.  I will just have to make this work, I have plans on building a drying "patio" in the future. 

I really can't speak to the sawyers methods in Minnesota, but it does seem like it is working for him. He produces some gorgeous flat slabs.  The contrast between the sapwood and heartwood is amazing. 

After taking the measurements and seeing the discrepancy between the top slab and lower slabs I am inclined to pull them out of the kiln and shuffle the top to bottom.  Until just recently I was using two foam panels to baffle the slabs, but I switched to two sheets of 1/4 plywood as they are less prone to moving, I use pieces of plywood to baffle between the kiln walls and the slabs. About two weeks ago I added three box fans between the back of the slabs and the L53 unit.  The top baffle has two auxiliary Mechatronics fans blowing towards the doors with a slight angle. 

All slabs are cut at 9/4 with exception to one or two that are typically on the bottom of the log when milling.  It seems really odd that I got measurements in the 40-50% range, as I took a few measurements from slabs (also claro walnut) that have been air drying for a few weeks and got readings in the 35-45% range.  It may be time to purchase an anemometer to maximize my kiln design.

Do you have problems with the fans moving the canvas in the kiln? The foam was so light that occasionally the pieces would shift, the plywood seems to have solved this problem.   

When it comes to oven dry samples with slabs, do I need to rip the slab in half? Or can I take a cut 12" from one end across the gran and use that piece as my sample?

I am determined to find a drying schedule that will work for Claro, as I have 1000's of bd ft of walnut to mill and dry in the next few months. 

Once again thank you for the great information, great community!

Merry Christmas!

-Marco





PC-Urban-Sawyer

Marco,

I think one problem you have is relying on meters to determine moisture levels.

As I understand it, even the best quality meters are not reliable at higher moisture levels. I think the cutoff point seems to be in the 30 percent range.

On the other hand, using the oven method to determine moisture level seems quite reliable if you have an accurate set of scales for the range you are weighing.

Good luck!

Herb

GeneWengert-WoodDoc

Under 30% MC, the Delmhost pin meter has been confirmed to be within 1/2% MC or better for North American.species, if they are used correctly with insulated pins driven 1/4 the thickness, etc.

The oven test requires some care as well...215 F until weight loss stops and a scale or balance that measures to two decimal places.

For example, if the sample weighs 55.0 grams and the oven dry weighs 50.0, the calculated moisture is 10.0% MC. However, with two digits, the weights are 55.05 and 49.95.  This gives 10.2 % MC.  So, with one digit, we have an uncertainty of around Plus or minus 0.4% MC.  With no digits, the uncertainty is 4% MC.  This assumes the balance is working perfectly and is properly calibrated.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

YellowHammer

For oven dry samples, I usually have at least one slab that has a poor end, or one with cracks, or one that will need future dressing.  So I cut samples off and weigh them and write in on them on the samples with a Sharpie.  Once the preliminary weighing and drying are done, the only thing that is required to get a new moisture content is to take the piece and put it on the scale and run the calculation.  I determine the new MC, write it on the sample piece, and put it back in the kiln.  I keep the scale in the kiln controller box, so the whole process only takes a minimal amount of time.  I've got a slide hammer for my Delmhorst but I prefer to weigh thick slabs, just because I know its right, and its fast and easy.  I use a food scale, $25 or so at WalMart.  The sample pieces are relatively small, and would be trimmed anyway.

I use 2 inch foam as a baffle from the horizontal fan deck to the lip of the forward lumber stack in the kiln.  I don't like to have free air blowing over the top layer, so I try to simulate a layer of wood on top of it.  I use canvas and stickers to weigh it down.  I've also used burlap, and even corrugated metal roofing, the same way I cover the top layer of wood in the solar kiln.  Sometimes I'll even use the foam board.  Just depends on what seems to wok best.  Its very helpful to standardize the lumber height of the stack so once the configuration is optimized, I don't have to play much with it on successive loads.  By the way, if you have found that due to the inlet plenum size of the stack (from of pressure side of the stack to nearest wall) is causing a significant pressure drop and air flow reduction across the face of the stack, and causing the air to cheat, the burlap sheet technique is a good way drape over the upper layers and force air to go down to the lower level of wood in the stack.  If thats the case, then it should be a temporary measure and either the kiln or stack geometry should be addressed on successive loads.

Typically, most of this aggravation is goes away with pre air drying as kiln airflow and velocity have much less influence as the wood drop MC. 

   
 
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

maderahardwoods

Thank you guys guys again.  I think I will take 12" off one of da longer and shorter slabs and use dat as disguy's core sample. 

I think yoozguys may be on ta something, I wonder if having da shorter slabs centered on da longer slabs with side baffling is causing some issues. I will take some updated photos of da stack and baffling tomorrow. 

Thanks,

Marco

xlogger

Quote from: YellowHammer on December 26, 2017, 10:10:51 AM
For oven dry samples, I usually have at least one slab that has a poor end, or one with cracks, or one that will need future dressing.  So I cut samples off and weigh them and write in on them on the samples with a Sharpie.  Once the preliminary weighing and drying are done, the only thing that is required to get a new moisture content is to take the piece and put it on the scale and run the calculation.  I determine the new MC, write it on the sample piece, and put it back in the kiln.  I keep the scale in the kiln controller box, so the whole process only takes a minimal amount of time.  I've got a slide hammer for my Delmhorst but I prefer to weigh thick slabs, just because I know its right, and its fast and easy.  I use a food scale, $25 or so at WalMart.  The sample pieces are relatively small, and would be trimmed anyway.

I use 2 inch foam as a baffle from the horizontal fan deck to the lip of the forward lumber stack in the kiln.  I don't like to have free air blowing over the top layer, so I try to simulate a layer of wood on top of it.  I use canvas and stickers to weigh it down.  I've also used burlap, and even corrugated metal roofing, the same way I cover the top layer of wood in the solar kiln.  Sometimes I'll even use the foam board.  Just depends on what seems to wok best.  Its very helpful to standardize the lumber height of the stack so once the configuration is optimized, I don't have to play much with it on successive loads.  By the way, if you have found that due to the inlet plenum size of the stack (from of pressure side of the stack to nearest wall) is causing a significant pressure drop and air flow reduction across the face of the stack, and causing the air to cheat, the burlap sheet technique is a good way drape over the upper layers and force air to go down to the lower level of wood in the stack.  If thats the case, then it should be a temporary measure and either the kiln or stack geometry should be addressed on successive loads.

Typically, most of this aggravation is goes away with pre air drying as kiln airflow and velocity have much less influence as the wood drop MC.
 
Robert I've been thinking about weighing samples which I not done in the past. I was reading in the Nyle book what formulas to use. How big of a piece of slab do you cut off? If you can would you take a quick picture of it next time you get a chance.
Thanks

   

Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

GeneWengert-WoodDoc

The technique of using sample boards is well documented in Drying Hardwood Lumber...available on line from many sites.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

YellowHammer

This is the kind of trim I use and cut for kiln samples as I put in a load.  I don't cut regular or textbook sized pieces, just whatever is representative of the load, large enough to get a decent measurement, and what seems to makes sense.  Cut out an irregularities, cracks, pith or anything else that may make the sample non representative.  Then I take the piece and half it, and use one for the oven sample, and one for the kiln sample.  Since these are walnut, I re-use the sample boards and saw them into small, sellable pieces, maybe 2"x4"x12" or similar when the load is done and I'm not wasting wood or money.  Personally, I learned a lot when I first did the technique, and it really is pretty easy.  It also takes out all the guesswork and will answer lots of question about the accuracy of your meters.  Take a weight, calculate a MC, and then check it with the meter.  I have done this many, many times, and it has proven invaluable.  Lets just say, I originally had three different types of moisture meters, and I had no confidence in any of them.  In very short order, I finally believed one of them, and the other two were literally tossed in the garbage can.   
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

xlogger

Thanks Robert, next week it's going to really cold here so I'll have time to figure this out I hope. Maybe need to go further south to your place and look and learn. ;D
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

GeneWengert-WoodDoc

Robert makes a key point...we are concerned about the MC of the useable wood, so moisture samples should not have defects.  We want the samples to represent the other good and expensive pieces in the load. 

As samples are typically full width and 30" long, they are end coated with a coating that will stop moisture loss from the ends (making them behave like they are long pieces of lumber) and will not melt off.  Paint is not good enough, Anchorseal end coating melts but their BOSS product is perfect, roofing tar is ok too, and there are a few other brands of sample end coating.  To get the samples' initial MC, we cut 1" long pieces from each end before end coating and weigh, oven dry, reweigh, and calculate the MC.  The average of the two small pieces is the estimated MC of the 30" sample board.

For wetter the stock, the sample needs the same air flow, RH, and temperature as the rest of the lumber in the kiln.  For 25%MC or lower, air flow can be different as variation in air speed does not affect drying speed at lower MCs.

Using this technique, any time you need the current MC, weigh the sample board and calculate the MC in seconds.  YH even has a computer spreadsheet that does the calculations for you.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

YellowHammer

Ricky,
Come on by anytime. 
I have a spreadsheet I made years ago that does the calculations, and automatically graphs the moisture drop. 
 
If anyone wants it, send me a PM with your email and I'll send it to you. 
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

maderahardwoods

Update:

Oh man what a week, my wife came down with a serious stomach flu and was out from Tuesday evening to Friday evening.  While at the same time this was going I had to replace 90ft of water main line which required the cutting and patching of 40ft of concrete. 

Wife is finally back in action and water line at my dads place is patched and leak free so far. 

So Sunday morning I opened up the kiln completely with intentions to rearrange all of slabs from top to bottom and measure the moisture content of each slab in three places (far right, center, and far left).

I started with the slabs on the top stack, they were pulled out and rearranged, all of the moisture contents are captured in the photo below.  I then moved on to the long slabs, after the third all of the moisture contents were reading from 45-60% so I decided there was no point in rearranging the 12ft pieces. 

The first photos show the original arrangement of the kiln, I had the shorter slabs centered on the longer slabs with the sides baffled.  I decided to maximize the kiln charge and place some smaller pieces to side of the shorter pieces, which also made it easier to baffle. 

I really have no idea how the 12ft slabs are still 45-60%+ moisture content, they have been in the kiln for almost two months.  Do I have extreme case hardening? Is Claro Walnut just a slow drying wood?

I am considering asking a local hardwood processor if they are willing to sell time on their vacuum kiln as I really need to get some dry wood to market.

Slabs are currently at 120DB with the WB at 85, just going to try and follow the advice from the sawyer from Minnesota for the time being. 

I thinking about coating the slabs with pentacryl, I have read that it prevents the crotch grain and figure from drying to quickly and can also speed the drying up by 30%.  I have had some issues with the crotch grain drying to quickly and checking/"collapsing". 

Once again any help is appreciated. 



 

Original Stacking



  

 



  



 



 

WLC

I know absolutely nothing about drying in a DH kiln, but it seems to me that they would've air dried to a lower MC (especially in you CA climate) than that in two months if they had been stacked outside under a shed.  Something must be "off", what it is I have no idea.
Woodmizer LT28
Branson 4wd tractor
Stihl chainsaws
Elbow grease.

YellowHammer

Did you baffle the skids?  Floor to first layer?

The plastic sheet drops down to cover the doorway?  I haven't seen that before, not sure what purpose it would serve? 

The side baffling looks fine. 

I can't see behind the plastic to see the fans clearly?  Mine are mounted horizontally through the fan deck, blowing toward the ceiling.  Yours are near vertical?  With the sheet down and the doors open, you should see a very pronounced billow of the plastic sheet out the door as the air is pushed along the ceiling, against the plastic sheet, down the front of the stacks, and forced through the the stack.  The billow would be caused be the back pressure forcing the air through the front of the stacks. 

I like the steel runners.

Thats some pretty wood.

   

 
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

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