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Forum topic by Burbs posted 10-05-2016 03:37 AM 347 views 0 times favorited 9 replies Add to Favorites Watch
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Burbs

34 posts in 148 days


10-05-2016 03:37 AM

I scored some really heavy hardwood pallets that I suspected were oak and after posting some pictures on this forum, it was confirmed very quickly. Thanks guys.
Anyway, I should hopefully get 12-4×4’s that are 7 feet long and relatively straight. Will also have many pieces that are 2” thick and 9×30” or so.
My intention at least atm is to use the 4×4’s as legs and stretchers for a future workbench. These being pallets and ridiculously heavy, I’m pretty sure there wasn’t much drying that went on with this wood. I’ve cut, planed and squared up some of the 8/4 boards and it seems very dry.
I have a somewhere climate controlled shop. Dehumidifier running in an insulated garage stall and heated all winter. Going to stack and sticker these in my shop, weigh them down and put the big fan on one end blowing toward the dehumidifier on the other end.

So lots of rambling, here’s the real question, how long should I wait before using these 4×4’s? Should I go out and buy one of those cheap moisture meters? Do the oven drying method to determine moisture? Any recommendations on moisture meters? Thanks in advance if you can help.

-- ---The day I learn nothing of value will be the day I'm laid to rest--- Burbs


9 replies so far

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a1Jim

115202 posts in 3042 days


#1 posted 10-05-2016 03:50 AM

My experience with cheap moisture meters is kind of underwhelming, If you’re going to do woodworking invest in a decent moisture meter otherwise you will be doing what you’re doing now ,trying to figure out what to do. If you guess wrong then you put a lot of work into making a nice piece of furniture and then have it twist or cup all over the place because it wasn’t dry when you milled it.

-- http://artisticwoodstudio.com Custom furniture

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Lazyman

695 posts in 852 days


#2 posted 10-05-2016 02:15 PM

Jim is right about the cheap pin style meters being not so great. For one thing I don’t like to stick pins into a piece of wood that is cut to final dimensions. Plus getting them far enough into hardwoods to get an accurate reading is difficult at best, not to mention that they generally aren’t strong enough that you can wack them in, even with a rubber mallet. On the other hand, they can give you a idea if you use them on a an offcut immediately after cutting it off because they’ll work okay without having to hammer the pins in as deep. Amazon has some cheap pin style meters that all look like they are made by the same company.

One thing that you can try if you don’t have a meter is weighing a small offcut on a kitchen or postal scale that has 10ths of an ounce or gram graduations, microwaving for about 30-60 seconds on 50% power (or less if the pieces is really small or thin—you don’t want it to start to burn) to measure how much moisture is lost by weight. Let it cool, weigh it again and repeat until it stops losing weight. I am sure that it depends upon the type of wood and other variables like the shape and thickness of the wood but once it stops losing weight, I generally find based upon my cheap meter that you can assume the moisture is between 15 to 20%. At that point you can compute the rough percentage of moisture loss to get an idea of where the piece was before drying. If a small offcut doesn’t lose much weight as a percentage during the process, it is probably dry enough to use or at least won’t need as much time to acclimate to your location. I’ve done this when rough turning small bowls from green wood and measured the moisture content with my cheap meter and the calculations come out reasonably close to what the meter shows before and after the microwave drying process.

BTW, I bought a used microwave at a garage sale for $8 to use for drying rough turned bowls. I don’t use the one in the kitchen for this. If you use the one in the house, you will want to put the wood in a pyrex baking pan with a lid to keep from getting the microwave too smelly. Be prepared for complaints!

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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a1Jim

115202 posts in 3042 days


#3 posted 10-05-2016 02:40 PM

Sorry to disagree with the use of the drying method, I know that some calculation of moisture content is better than none but the moisture loss aproach of drying and weighing the wood in my opinion , can be even less accurate than a cheap moisture meter. Assuming your testing a small cut off by its size alone will have less moisture than a longer board because it has two end grains close together that lose moisture much faster than the inside of a longer board that’s why end grain is sealed after milling wood,so you starting you calculation with a poor representation of what the rest of the boards moisture content is before you dry it.

-- http://artisticwoodstudio.com Custom furniture

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pintodeluxe

4856 posts in 2278 days


#4 posted 10-05-2016 04:01 PM

It is interesting when I hear people worry about tiny pin holes from a moisture meter. The whole point is to dry lumber in its rough state. Once it drys fully and quits moving so much, we mill it flat and square. The pin holes are gone at that point. Some pin-less meters won’t take an accurate reading unless you plane a section flat first. For this reason I use a pin-type moisture meter. I tried a cheap meter first, but the readings would vary by 5-8% in the same part of the same board. Well, is it 8% or is it 16%? I quickly became tired of that, and purchased a Mini Lignomat. I have been entirely satisfied with the reliability and accuracy of that meter.

If you have a heated shop with a dehumidifier and fans… you have it made. It won’t dry as quickly as a kiln environment, but it will dry in time. My estimation is the pallet lumber would acclimate to 15% m.c. in a typical outdoor environment, and would be much dryer if stored inside for any length of time. You can go from 12% to 8% in a few weeks, but track the core moisture content with a reliable meter (cut a few inches off one end and test the center of the lumber).

Make sure you point the fans across the width of the lumber. The stickers will prevent even airflow if you orient them lengthwise.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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Lazyman

695 posts in 852 days


#5 posted 10-05-2016 05:16 PM

Jim, I am not sure that I understand what you are saying about oven drying vs moisture meters but meters are trying to estimate the results of the oven dry method of measuring moisture and is how MC certification is done. One problem with any pin style meter is that it is really only measuring the moisture content between the pins which are only about an inch apart so your sample is small. If you can only get the pins 1/16th or at most 1/8th of an inch into the wood, it won’t tell you much about the rest of the board, especially the center of a 4×4. And on the cheap meters, the pins are not insulated so you are probably just measuring the surface moisture anyway.

You are right that an off cut from the end grain will probably start out dryer than a sample cut from the middle or even ripped from side grain further away from the ends but that might be a little like cutting down a tree to see how old it is. If you can get your sample from the middle of the board, it will definitely yield more meaningful results.

Anyway, the method I described was for a quick and dirty calculation to get an idea of moisture content if you don’t have a meter.

You know what this means don’t you? My curiosity is now peaked and I may have to do some more experimentation with some air dried wood I have laying around. Now, I won’t get any “work” done.


It is interesting when I hear people worry about tiny pin holes from a moisture meter. The whole point is to dry lumber in its rough state. Once it drys fully and quits moving so much, we mill it flat and square. The pin holes are gone at that point.

- pintodeluxe

Pintodeluxe, Sometimes you need to check lumber that you have purchased or that is otherwise already milled to final dimensions to see if it needs time to acclimate or stabilize before finishing. I don’t need to do that often but I don’t really want to poke holes in it that I might have to fix later.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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pintodeluxe

4856 posts in 2278 days


#6 posted 10-05-2016 08:49 PM

Cut an inch off the end and check the end grain. I suppose it’s different for each woodworker. For me the pin style meters are great, because I don’t have to hand plane sections before taking readings.

On critical components like cabinet door rails and stiles, I will mill and then let the stack of parts acclimate for a day. Then I mill again for the most stable parts possible.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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Burbs

34 posts in 148 days


#7 posted 10-05-2016 11:19 PM

Thanks for the response guys. Didn’t mean to stir up a debate. The mini lignomat looks like it’s around $100 which isn’t horrible. Anyone else have recommendations on moisture meters? Most of the wood I’ve been getting is kiln dried but I have some maple that I cut on the bandsaw and is drying and a lathe is on the horizon so I’m going to have to start worrying more about moisture soon.

-- ---The day I learn nothing of value will be the day I'm laid to rest--- Burbs

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JBrow

818 posts in 384 days


#8 posted 10-06-2016 12:48 AM

Burbs,

I thought I would enter the fray with yet another method. This method uses the weight of dried wood and the volume of wood for which moisture content is sought. The method provides the moisture content of the entire piece of lumber, rather than moisture content of areas sampled. A little math is and a set of bathroom scales or other weighing device are required. Since The Wood Database offers Average Dried Weight (ADW) for various species of wood, where Dried means wood with a 12% moisture content, the Density of various species at a Moisture Content of 12% can be found.

The first step is to measure a stick of wood to determine its Volume, in units of cubic feet (VOL). Then the stick of wood is weighed (WT). For example, suppose you weigh a 4” x 4” x 7’ stick of Red Oak and find it weighs 34 lbs. The Volume of a 4” x 4” x 7’ this stick of Red Oak is VOL=.33’×.33’×7’=.76 cubic feet.

From these measurements the Density (D) of this stick of Red Oak can be calculated…

D=WT/VOL=34lbs/(.76 cu ft)=44.7 lbs/cu ft

From this measured Density of the Red Oak, the calculation of its Moisture Content (MC) can be done, where MC = Moisture Content; D = Density of a stick of wood; ADW = Average Dried Weight…

MC=(12%×D)/ADW=(12%×44.7 lbs/ cu ft)/(44 (lbs.)/cu ft)=12%

where Average Dried Weight of Red Oak from The Wood Database is 44 (lbs.)/cu ft

But if the stick of Red Oak weighed 50 lbs. instead of 34lbs. the Density of the Red Oak stick would be…

D=WT/VOL=50lbs/(.76cu ft)=65.8 lbs/cu ft

And from this the Moisture Content of the 50 lb. stick of Red Oak with a Volume of .76 cu ft would be…

MC=(12%×D)/ADW=(12%×65.8 lbs/cu ft)/(44 (lbs.)/cu ft)=17%

http://www.wood-database.com/

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fuigb

403 posts in 2422 days


#9 posted 10-06-2016 06:18 AM

I’ve also found a vein of hardwood pallets, mixed bag of red and white oak, hard and soft maple, sycamore, birch, beech, and ash. So much that i’m seriously considering an attempt on post/beam construction shed for the material that I don’t want for proper woodworking.

My lumber is found in a range from pretty dry to nearly dripping wet. My solution for the wet has been to build a knock-down dehumidifier kiln (also from found materials). Results with the dehumidifier are frustrating so for the most part I run a small desk fan and a 100 watt bulb, but I will add a small ceramic heater when I find one at the right price. One day I’ll create a blog here to illustrate the process, but the essence of the kiln are six lightweight sections that are set up in the form of an insulated box that looks a bit like a crude coffin for a very tall and very fat man. A month or two in the box is usually enough for the 2×3x48 runners from my pallets.

-- - Crud. Go tell your mother that I need a Band-aid.

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