Results 1 to 14 of 14

Thread: how dry is dry?

  1. #1

    how dry is dry?

    Just bought a moisture meter and was wondering at what point do you guys consider a bowl blanks to be dry. Need to know at what point do you guys switch your bandsaw blades from cutting green wood to cutting dry wood. Any info will be greatly appreciated!!! Thanks again.

  2. #2
    Join Date
    Feb 2008
    Location
    IL.Quad city area
    Posts
    783
    Well I don't turn bowls but I've turned many hundreds of hollow vessels starting with green wood roughing them out then air dying and returning them. The EMC will vary by region in my area I'll return anything that's in the 8 to 12% range.
    As for band saw blades I only change them when either there dull or break, I use the same blade for both green & dry wood.

  3. #3
    Paul, I don't switch bandsaw blades, because I don't cut drippy wood. My interest in dryness is based on shrinkage, warping and cracking. IMO wood is dry enough to finish at approximately 6% to 12% depending on the species, what you plan to do with it, where you live. I am a novice at drying home-harvested wood. Maybe an expert will come along and set us straight.

    I am drying some red mulberry as I write this. If I had the space or a pickup with a topper it would be in a solar kiln or the back of the truck. But I have had to stack some outside and some in my unheated garage.I live near Denver and I will use it to make staved vessels. I will not use it until it is about 8-10%. I'm not sure how I will get it there, but a warm oven is a possibility if a year of air drying is not enough.

    Doug

  4. #4
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    12,298
    I cut both drippy wood and dry wood turning blanks with the same blades: 1/2" 3tpi.

  5. #5
    Like the others here I don't change blades from wood that fell hours ago to wood that has been stored for years. I don't use a moisture meter I just weigh a twice turned piece and when it stops loosing weight I believe it is dry.
    Pete


    * It's better to be a lion for a day than a sheep for life - Sister Elizabeth Kenny *
    I think this equates nicely to wood turning as well . . . . .

  6. #6
    For furniture making, you want it to be in the 6 to 8% range. With twice turned bowls, you could get away with 10% and have minimal movement. Outside wood will dry down to 10 to 15% depending on your local weather. Inside the shop, you can get to the 6 to 8%. I don't do the twice turned bowls, just turn green to final thickness. I can pretty feel how dry the woods are just by picking them up...

    robo hippy

  7. #7
    Thanks for the input guys!!!

  8. #8
    Join Date
    Jul 2007
    Location
    NE OH
    Posts
    2,615
    Here's a link to an equilibrium moisture content chart for wood: https://www.finewoodworking.com/FWNP...tent-chart.pdf

    It will tell you what moisture content wood will eventually reach given relative humidity and temperature of the storage area. For example, if your shop RH is 50% and temp is 60 F, wood stored in the shop for a long time will reach equilibrium moisture content of 9.4%.

    Of course, not many shops stay at constant RH and temperature, so in reality the moisture content will always be varying slightly, but the chart will give you an idea of whether a particular wood sample is about as dry as it's going to get under your conditions.

  9. #9
    Join Date
    Feb 2008
    Location
    lufkin tx
    Posts
    2,054
    Knowing the MC of your wood is nice to know. The species and characteristics are just as important though. Hardness, fine grain, high strength all effect performance while working. These 3 properties all make wood split much easier. Soft weak woods are often almost split proof but they all will probably move while drying. Double turning and endsealer will eliminate these problems usually.

  10. #10
    Join Date
    Apr 2018
    Location
    Cambridge Vermont
    Posts
    2,282
    What did you get for a moisture meter? I have a cheap General pinless one and find it's not very accurate.

  11. #11
    I got an over the counter one from lowes. Cant remember the name and its raining right now so I cant get to the shop. Based on reading from some new wood blanks and some blanks ive had setting around for several months i would say its pretty accurate. Seems like I saw a post on here about a fellow that had one and it read withing 1-2 percent of a meter that cost hundreds more.

  12. #12
    Join Date
    Apr 2018
    Location
    Cambridge Vermont
    Posts
    2,282
    My local Lowes stocks a pin and pinless style. Both are General brand. I have a slightly different version of the pinless one they sell but it's basically the same just a different ergonomic style. It has a setting 4 settings, one is for hardwood. It seams to work ok but I'm not convinced of it's accuracy. I've been mainly relying on using a scale. Without a kiln yet I would like to know how dry the blanks are when they equalize to my basement. With blanks that are green the meter just reads 35% and when they seam to be as dry as they are going to get according to the scale it reads 8%. I think I've only seen one reading in the middle which as made me question it. I was asking simply because I wanted to know what you've seen with yours.

  13. #13
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    12,298
    Quote Originally Posted by Alex Zeller View Post
    Without a kiln yet I would like to know how dry the blanks are when they equalize to my basement. With blanks that are green the meter just reads 35% and when they seam to be as dry as they are going to get according to the scale it reads 8%.
    You can test your meter by measuring a few small pieces of wood then using the oven dry method to determine the actual moisture content then compare that with your previous meter readings. I wrote this earlier of checking some ebony:

    --------------------------------------------------------------------------------------------------
    Moisture content by oven-dry method
    https://sawmillcreek.org/showthread....ven-dry-method

    I got some waxed 1" square Ebony blanks from Pete Kekel (Big Monk Lumber in KY) with unknown moisture content. Waxed wood blanks can be anywhere from green to dry and I find it difficult to guess with hard exotics. My pinless moisture meter needs a bigger contact area so I used the oven-dry method which gives the absolute moisture content independent of the density of the wood. This method is always accurate and cheap if you already have the simple equipment on hand.

    If not familiar with this, basically a wood sample is first weighed then gently dried in an oven and weighed repeatedly until the weight quits changing. Then subtract the dry weight from the wet weight to get the water weight and divide that by the dry weight to get the moisture content.

    I cut away the surface wax and cut samples from one of the Ebony blanks. A toaster oven dried the wood; a kitchen oven would work fine. I put a thermocouple in the oven to monitor the temperature (a thermometer would work fine). The temperture should be between 212 and 220, ideally 217. The little digital scale is good to 0.1 grams (checked with my triple-beam balance). I checked the temperature every few hours and quit when the weight was unchanged over two readings.

    The moisture content of this Ebony was just over 13% which matched the expected equilibrium MC of air-dried lumber in both TN and KY. It's good to know I can turn these without further drying.

    If interested in more detail: https://ir.library.oregonstate.edu/downloads/jm214q048

    ------------------------------------------------------------------------------------------------

    JKJ

  14. #14
    Join Date
    May 2013
    Location
    Smyrna Mills, Maine
    Posts
    95
    A simple method to tell when a twice turned bowl is ready to finish is by weight. After a few weeks/months of drying start weighing the bowl, when it stops losing weight it will be dry for finishing. Of course the bowl needs to be in a heated environment for this method to work but I had great results with this method and minimal investment for a small scale.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •