The Forestry Forum is sponsored in part by:

iDRY Vacuum Kilns


Forestry Forum
Sponsored by:


TimberKing Sawmills



Toll Free 1-800-582-0470

LogRite Tools



Norwood Industries Inc.




Your source for Portable Sawmills, Edgers, Resaws, Sharpeners, Setters, Bandsaw Blades and Sawmill Parts

EZ Boardwalk Sawmills. More Saw For Less Money!

STIHLDealers.com sponsored by Northeast STIHL


Woodland Sawmills

Peterson Swingmills

 KASCO SharpTech WoodMaxx Blades

Turbosawmill

Sawmill Exchange

Michigan Firewood, your BRUTE FORCE Authorized Dealer

FARMA


Baker Products

ECHO-Bearcat

iDRY Wood Lumber Vacuum Drying for everyon

Nyle Kiln Dry Systems




Author Topic: Conductivity and wood density  (Read 318 times)

0 Members and 1 Guest are viewing this topic.

Offline C_Miller

  • Full Member x2
  • ***
  • Posts: 208
  • Age: 62
  • Gender: Male
  • yes, we have trees in New York
    • Share Post
Conductivity and wood density
« on: February 14, 2019, 08:19:07 PM »
I run a Nyle LM200.   Sometimes I have a probe reading that  indicates moisture content considerably higher relative to other probes in the same stack of lumber. 
I am usually drying live edge 2 1/2" thick walnut, soft maple or oak.I haven't been able to establish a pattern. was wondering if wood density in the figured slab would affect the reading.
CJM

Online doc henderson

  • Senior Member x2
  • *****
  • Posts: 2513
  • Age: 59
  • Location: Hutchinson, Ks
  • Gender: Male
  • Evil Prevails when Good Men Standby and Do Nothing
    • Share Post
Re: Conductivity and wood density
« Reply #1 on: February 14, 2019, 08:34:02 PM »
I use a pin-less meter and it is definitely true with that.  Not sure, as I am no expert, with other meters.  I think @GeneWengert-WoodDoc , will have good info for you!
timberking B 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor 12 volt tarp motor

Offline Southside

  • Senior Member x2
  • *****
  • Posts: 5319
  • Age: 47
  • Location: Wilsons (Dinwiddie County), VA
  • Gender: Male
  • Have a plan to saw every log you meet.
    • Share Post
Re: Conductivity and wood density
« Reply #2 on: February 14, 2019, 08:49:12 PM »
Walnut is known for holding water pockets. I don't know why, but it does. 
Franklin buncher and skidder
JD Processor
Woodmizer LT Super 70 and LT35 sawmill, KD250 kiln, BMS 250 sharpener and setter
Riehl Edger
Woodmaster 725 and 4000 planner and moulder
Enough cows to ensure there is no spare time.

Offline YellowHammer

  • Senior Member x2
  • *****
  • Posts: 4343
  • Age: 54
  • Location: New Market, Alabama
  • Gender: Male
  • Take Steps to Save Steps
    • Share Post
    • Hobby Hardwood Alabama
Re: Conductivity and wood density
« Reply #3 on: February 15, 2019, 07:25:34 AM »
The probes measure electrical conductivity or electrical resistance between the probes, so anything that affects that will give a different reading, whether its from the wood, or the kiln sensors themselves.

Wet spots can be a problem, especially in walnut and white oak. However, there are other possible physical factors that I like to eliminate first as well.  

Sometimes the probe spacing is off, (30 mm between probes), sometimes there is reduced electrical contact on the probe and wire banana plugs, (I like to use a screwdriver to slightly expand the banana plug to more securely fit the probe holes, and I clean the contacts regularly), and sometimes its a function of where the probes are placed.  Closer to the end of the board will sometime give a different reading than in the middle, especially when in the higher than fiber saturation point or so MC range.  Also, its important for all the pairs of screw in probes to be set at the same depth.

If you swap the probe wires with another adjacent set then that will tell you about half the story.  Sometimes the high reading will go away, sometimes it will follow the wires.  Then if the  high reading remains, get a longer (or shorter, depending on the original probe length) set of screw probes and drive them in right next to the ones already in the wood and put the leads in them.  You should see the same reading or pretty close, based on the depth of the probes.  The shorter probes should read slightly drier than the deeper one, if there is a wet spot in the wood. Sometimes if I have a wet spot I will move one set of leads to the duplicate screw in electrodes, as that is a spot of interest, and since the Nyle uses average values for its algorithms, I like to concentrate the reading on the anomaly.  

Every now and then, I will get a block of wood, drive two probes in it, and insert each pair of wires in it, they should all read the same.  That will give confidence the machine is reading properly.

Once you are convinced you have wet spots, it won't be much of a problem until you get to the final drying stage where all the readings do need to match up.  If you can't clear the wet spot by the end of the cyclce, start raising the temperature until just under the compressor safety.  If the rest of the stack is at 8% or so and you still have wet spots, turn off the compressor and go into a sterilization cycle, raise the temps to 150, and hold for 24 hours, and then let it slowly drop for 24 hours.  Then turn the compressor to 100% by setting the wet build to 70%, and the dry bulb to 100% and give it a day os so and the wet spot will resolve.  
HobbyHardwoodAlabama.com

Offline K-Guy

  • Senior Member
  • ****
  • Posts: 257
  • Location: Bangor, ME
  • Gender: Male
    • Share Post
    • http://www.nyle.com/
Re: Conductivity and wood density
« Reply #4 on: February 15, 2019, 08:38:04 AM »
Once again a reply from me is unnecessary as Yellowhammer probably explained it as well or better than I can. :D 
Nyle Kiln Sales & Service
"He has all the virtues I dislike and none of
 the vices I admire." -Winston Churchill

Offline C_Miller

  • Full Member x2
  • ***
  • Posts: 208
  • Age: 62
  • Gender: Male
  • yes, we have trees in New York
    • Share Post
Re: Conductivity and wood density
« Reply #5 on: February 15, 2019, 08:15:10 PM »
Thanks Guys, I appreciate all the info. 

Put my pin meter on the probes and got the same reading as on the control panel.

Yellow hammer what did you mean by "compressor safety"?

Sounds like the water pockets will clear up with a thermal hammer tunk. I have been holding temps to high to long must be. I'll try just thumping it next time.
CJM

Offline GeneWengert-WoodDoc

  • Senior Member x2
  • *****
  • Posts: 2700
  • Location: Bishop, GA
  • Gender: Male
  • Author of "Sawing Hardwood Lumber"
    • Share Post
    • Book on Sawing hardwood Lumber
Re: Conductivity and wood density
« Reply #6 on: February 15, 2019, 11:00:21 PM »
Water pockets are almost always the result of anaerobic bacteria in the tree.  These bacteria creat a bacterial slime that inhibits the movement of moisture enough, so there there are small regions of wetter wood.  Sometimes, these regions are called bacterial wetwood, or just wetwood.  You will also see that the initial moisture is higher than normal.  For example, in red oak, normal green moisture is 75% MC, but bacterial Infected wood will have as high as about 110% MC, with 90% being commonly seen.  So, this higher starting MC and the restricted movement mean wetter wood zones.  It is worse with thicker pieces...seldom seen in 4/4.  Patience is the only cure.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Offline YellowHammer

  • Senior Member x2
  • *****
  • Posts: 4343
  • Age: 54
  • Location: New Market, Alabama
  • Gender: Male
  • Take Steps to Save Steps
    • Share Post
    • Hobby Hardwood Alabama
Re: Conductivity and wood density
« Reply #7 on: February 15, 2019, 11:43:19 PM »
The compressor has two safeties, a refridgerant low pressure shut off and a high pressure shutoff.  The high safety trips a little above 130 degrees in the kiln.  
HobbyHardwoodAlabama.com


Share via delicious Share via digg Share via facebook Share via linkedin Share via pinterest Share via reddit Share via stumble Share via tumblr Share via twitter

xx
Cypress density

Started by Yellabret on Drying and Processing

4 Replies
809 Views
Last post July 27, 2013, 05:30:10 PM
by Ianab
xx
canopy bulk density?

Started by ashes on Forest Education

6 Replies
1544 Views
Last post April 26, 2012, 01:18:34 PM
by SwampDonkey
xx
Variable-Density Thinning

Started by pappy19 on Ask The Forester

3 Replies
1417 Views
Last post September 30, 2009, 10:38:47 PM
by madhatte
xx
Natural tree density/acre

Started by livemusic on Ask The Forester

8 Replies
1101 Views
Last post February 20, 2017, 04:05:29 PM
by Ron Scott
 


Powered by EzPortal