Weighing green wood

[James McCall]

After roughing and sealing a green bowl I will weigh it and mark the date, reweighing every month or so until the weight stabilizes.

This feels like the most direct way of determining if the wood has reached equilibrium with the environment.

Lately I've been chasing my tail a bit with weights seeming to fluctuate a bit wildly. At first I chalked it up to the changing season from spring to summer but the changes were in the range of +/- 10% which seemed to significant.

I've come to realize that my little kitchen scale is quite sensitive to where the bowl is placed on the surface and I must not have been consistently weighing my bowls in the same place on the scale.

Seems obvious on reflection but I don't think I've come across the issue in discussion.

My solution is to tape a short cylinder to the surface of the scale which would locate the tenon of the bowl to ensure consistent placement.

 

[Alan Weinberg]

Or get a better scale.

 

[James McCall]

Or get a better scale.

I could but no guarantee that another scale won't have similar issues and I have other stuff I'd rather spend money on.

 

[Don Wattenhofer]

I have been doing that for more than 10 years, started using a commercial mail scale that was junk due to the fact that the postage rates could no longer be updated, then about 6 years ago I bought a small digital mail scale that would read in whatever units I preferred. The digital scale is set to read out in grams and doesn't seem to be sensitive to position.
The regimen I use is to weigh when first off the lathe, record the weight and put into a brown paper bag.
Then about a day later weigh and record the weight.
The time between weighing intervals gradually increases and the weight change will decrease until there is no change.
The weather conditions I have in what some people from warmer climates, refer to as the frozen north means that the inside humidity is very low in winter but in summer the humidity rises and some pieces may increase weight by up to 2 grams in the summer.

 

[John K Jordan]

I've come to realize that my little kitchen scale is quite sensitive to where the bowl is placed on the surface and I must not have been consistently weighing my bowls in the same place on the scale.

James,

I've been tracking air-drying wood with weight for at over 15 years, not often with roughed bowls but with hundreds (maybe thousands) of rectangular blanks.
I think your idea of using something to even out the force on your scale surface is a good one.

I once had an accurate antique grocery store scale but I gave it away. Too bulky.
After trying a number of small scales, this is my favorite - inexpensive, fits in a drawer, I keep a second one just in case.
Doesn't seem to matter much where I place the blank on the surface. Claims it will weigh up to 33 lbs, about 15000 grams.

Amazon.com

When I cut blanks from green wood on the bandsaw, I seal immediately but usually wait for a while (a week or more) to let things stabilize and let me check for and cut away any early checks or cracks that develop. Since these are solid, some large blanks may take 10 years to dry. I'm not impatient since I have more than enough already dry to turn or give to friends.

For recording weights, I use a piece of green tape (Scotch 2060 sticks to almost anything. )
I write the weight in grams and date and periodically reweigh. The absolute weight doesn't matter, of course.
Blanks for drying are stored on wire shelves or loose in tubs with plenty of ventilation.

*** I do see seasonal changes, even though my shop is climate controlled - I don't keep it too cold in summer or too warm in winter. The climate in this area is often humid. Having quantities of wet wood drying adds to the humidity in the building.

A few straight off the bandsaw just sealed, and some after drying for months or years. (old photos)


When I see the weight stabilize or go up a little I'll track it for a few more months then mark it dry.
Note: I don't monitor every piece - a piece or two of typical size from a batch. When a larger piece from the same batch is dry, I assume smaller piece are also dry. When dry, I stack them tightly.



This has worked for me but I do things differently on the rare occasion I rough-turn bowls.

JKJ

 

[James McCall]

James,

I've been tracking air-drying wood with weight for at over 15 years, not often with roughed bowls but with hundreds (maybe thousands) of rectangular blanks.
I think your idea of using something to even out the force on your scale surface is a good one.

I once had an accurate antique grocery store scale but I gave it away. Too bulky.
After trying a number of small scales, this is my favorite - inexpensive, fits in a drawer, I keep a second one just in case.
Doesn't seem to matter much where I place the blank on the surface. Claims it will weigh up to 33 lbs, about 15000 grams.

Amazon.com

When I cut blanks from green wood on the bandsaw, I seal immediately but usually wait for a while (a week or more) to let things stabilize and let me check for and cut away any early checks or cracks that develop. Since these are solid, some large blanks may take 10 years to dry. I'm not impatient since I have more than enough already dry to turn or give to friends.

For recording weights, I use a piece of green tape (Scotch 2060 sticks to almost anything. )
I write the weight in grams and date and periodically reweigh. The absolute weight doesn't matter, of course.
Blanks for drying are stored on wire shelves or loose in tubs with plenty of ventilation.

*** I do see seasonal changes, even though my shop is climate controlled - I don't keep it too cold in summer or too warm in winter. The climate in this area is often humid. Having quantities of wet wood drying adds to the humidity in the building.

A few straight off the bandsaw just sealed, and some after drying for months or years. (old photos)
View attachment 76490 View attachment 76491

When I see the weight stabilize or go up a little I'll track it for a few more months then mark it dry.
Note: I don't monitor every piece - a piece or two of typical size from a batch. When a larger piece from the same batch is dry, I assume smaller piece are also dry. When dry, I stack them tightly.

View attachment 76493 View attachment 76492

This has worked for me but I do things differently on the rare occasion I rough-turn bowls.

JKJ

You prefer drying blanks rather than roughing out green? I definitely enjoy turning while it's still green soni find that a bit surprising. But different things work for different people's situations.

 

[John K Jordan]

You prefer drying blanks rather than roughing out green? I definitely enjoy turning while it's still green soni find that a bit surprising. But different things work for different people's situations.

Different strokes, for sure.

I've turned plenty of big bowls and platters, sometimes roughed and turned later, sometimes finished turned with "natural" edge.
When I have green logs, some large, I love providing it for friends and club members. I have equipment that makes hauling, lifting, sawing, and loading trivial. I've posted photos here in the past. When I have logs I always keep some for myself to process into blanks to dry.





Some somewhat random thoughts:
I simply like turning dry wood.
Many things are best made starting with dry wood. But try to find large, dry blanks. (ex: 10"x10"x14")
I far prefer to turn smaller things, often with detail.
I like to turn some things where warping is undesirable - dry end grain is good for this.
Please don't take the wrong way, but turning green local hardwoods is fun but easy, not much challenge.
Hollow forms from green wood? Been there, done that, got the tee shirt.
I love spindle turning - not chair legs but thin spindles, finials, etc. These are best turned dry.
I love the process and challenge of making high-quality dry blanks from wet wood.
Turning wet can be messy. I make plenty of mess with dry wood but it's easier to clean up.
Green wood around here is cheap or free, but dry wood is also cheap or free if I dry it myself.
I love providing useful wood to friends and donating to club benefit auctions.
If we all did the same thing, life might not be as interesting.

I know twice-turning lets me start with green and turn dry. But I'll leave that for others.

But I'm no dry-wood snob. I'll gladly cut up green wood blanks for those who want them.


I made a video for a pandemic zoom demo of how I process green log sections into blanks for drying. If interested, it's posted here:

Thread 'Making useful turning blanks from logs'

Oct 8, 2024

My “Logs to Blanks” video shows how I use a shop bandsaw to make useful turning blanks from log sections. I almost always turn dry wood so I include a little information on drying.

I made this video during the Covid pandemic for a club Zoom meeting demo. It’s long, about 45 minutes, but it’s a severely cut down version of my 4-hour bandsaw class - I had to leave out a lot of information but this might be a good introduction. I tried not to skimp on safety!

I shot and edited this video in a rush so it seriously needs some changes and additions. Unfortunately, the chances of me...

• John K Jordan
• Replies: 3
• Forum: Tutorials and Tips

• 
• 

Could use some changes, but perhaps interesting the way it is to some.

JKJ

 

[robo hippy]

Well, some day I may get around to twice turned bowls. If I was to go that way, I would rough out so many of them that I would not bother with weighing them. Kind of like my box blanks I rough out. Kind of forget about them till it is time to turn. I guess I would stack them in some order.... My favorite wood to turn is Pacific Madrone, and you either have to boil it or once turn it and let it warp, which is my preferred method. It warps any which way it wants to, and there is no rhyme or reason to how it moves.

robo hippy

 

[John K Jordan]

...would not bother with weighing them. Kind of like my box blanks I rough out. Kind of forget about them till it is time to turn. I guess I would stack them in some order....

That what Raffan said to do, and I do the same with boxes when I start with green wood, let them dry for a month or so. He says tape the top and bottom together, hollows out, to keep from mixing them up.

Another thing is to turn almost to finish size with dry wood then let set at least overnight to allow any stresses to relieve.

 

[James McCall]

That what Raffan said to do, and I do the same with boxes when I start with green wood, let them dry for a month or so. He says tape the top and bottom together, hollows out, to keep from mixing them up.

Another thing is to turn almost to finish size with dry wood then let set at least overnight to allow any stresses to relieve.

So essentially twice turn dry wood? Second turning the next day just to remove whatever minor movement occurs?

 

[John K Jordan]

So essentially twice turn dry wood? Second turning the next day just to remove whatever minor movement occurs?

Yes. Wait a day or three before finish turning, even with dry wood. It's amazing to me how much internal stress some completely dry wood develops. Stress relief is usually not problem on a typical bowl but a potential fatal problem for a precision box lid fit.

And all bets are off, of course, if the wood isn't absolutely dry. Even small blanks of some apparently dry wood can still warp so much it still can't be used for a box. Dogwood is one of the worst I've experienced since it's so dense and dries so slowly and naturally warp like crazy. I rough turned the box base and this lid from a small dogwood blank I THOUGHT was dry after months on the shelf but obviously not dry enough. A few days after rough turning the lid shrunk this much more tangentially than radially. Egg-shaped, unusable for the box.



I've turned other dogwood end-grain boxes but learned a lesson: turn dogwood THREE times! First, hollow with a thick enough wall to accommodate warping while drying. Turn a second time to a thinner wall after a long drying period. Turn the third time to final fit after waiting a few days days for the stress relief. (Note: this was before I started to track dryness by weight instead of guess. Things are simpler now. )

The most dramatic stress relief I've experienced: I once mounted a piece of completely dry 8/4 hard maple by the top with a screw chuck and turned most of the foot and bottom of a small squarish dished platter. Went to get something and heard a loud "CRACK" from across the room. By the time I got back to the lathe I heard it crack again! Removing some of the wood had allowed internal stresses to release enough to make it crack

I saved that one by quickly turning away the corners and the crack and made it into an odd small bowl. I don't have a picture from the top but this is the bottom:



JKJ

 

[David Wyke]

I use a produce scale with a metal bowl on top of it. All my first turn bowls fit very secure on it whether they are 6” or 18”. I write the date and weight, and don’t weigh again till about 6 months out. I check weekly for cracks and address those if they appear. Once they start getting Cole to second turn weight around 10-12 months I’ll switch to a digital postal scale. However the produce scale seems to be about as accurate for weighing.
I have around 175 bowls on the shelf separated by turning date (within a month or two)so I know what is dry and what needs a few more months.

 

[Webb Willmott]

Anybody use a moisture meter instead of weight or with weight?

 

[Don Wattenhofer]

Anybody use a moisture meter instead of weight or with weight?

The moisture meters will only tell the % near the surface so obviously that will not be a useful indicator.

 

[James McCall]

The moisture meters will only tell the % near the surface so obviously that will not be a useful indicator.

I don't go that route personally but I think it can still be a useful method.

Weighing the bowl tells you how the weight of the entire bowl is changing.

Measuring with a moisture meter may be useful for understanding how different parts of the bowl are drying at different rates.

 

[Larry Copas]

I have a sawmill along with a kiln so I get quite involved with proper moisture content. Weighing samples is the most accurate followed by meters. The last time I needed a scale I did a little research and found one at Harbor Freight at a low price that I thought would work. Went to the store and they were sold out but the friendly clerk suggested I go to a "Head Shop" as they have really good scales to weigh something or other. I did and found a great scale.

I also have a couple of meters. They come either with pins or pinless. I have both and they are close to the same in accuracy. The pinless is a Wagner and the pin meter is a Delmhorst. Both are probably far north of $500 in today's market. The Wagner pinless will measure moisture content to about 1/2" deep. I have a hammer drive for my Delmhorst and it will accurately measure to 2" deep but ya have those ugly holes to deal with.

I usually don't get to concerned with moisture content on turnings unless its something like a lidded box or a tenon that has to precisely fit a mortise. For a bowl I might make a quick check with the pinless or weigh but I'm also comfortable with holding it to my cheek and seeing if it feels cold.

 

[John K Jordan]

Anybody use a moisture meter instead of weight or with weight?

I use two moisture meters, a pin-less and a pin meter. Each has strengths and weaknesses.

For example, the pin-less needs a flat surface on the wood at least as large as its sensor. Reads only a certain distance into the wood from that surface. The meter needs to know the density (specific gravity?) of the wood so to switch from cherry to osage orange requires entering a number from a table or looking it up on a website.

The pin meter only reads the moisture at the surface (or as deep as the pins will go), apparently by electrical conductivity, not species dependent.

Due to the natural drying at the surface and the resulting moisture gradient inside the wood, both of these can be useful but don't tell the whole store. Weighing alone won't give the moisture content but the change in the weight can tell when the wood reaches EMC, equilibrium moisture content. Hydroscopic materials like wood gain or lose moisture depending on temperature and relative humidity of the environment. I think monitoring the weight change is the most practical method for woodturners.

There is one good way I know to get the absolute moisture content of wood - the oven dry method That involves weighing a sample with a precision scale (the sample can be small), heating at a recommended temperature until all the moisture is gone, weighing again, and calculating the MC from the two weights. I did this once with a batch of ebony where the dealer didn't know how dry it was. Knowing the absolute MC and the approximate relative humidity of the environment can show if the wood is well air dried.



That's more than I know about all this. Lets not get started with kiln drying. Makes my head hurt.

JKJ

 

[robo hippy]

When turning boxes, no matter how "dry" you think your wood is, I ALWAYS rough turn and rough hollow them out and let them rest. The reason, especially for wood thicker than about 8/4 or 2 inches, the inside is not at equilibrium. Also, just about any wood will "adjust" to having bulk removed. Eric Lofstrom has some "Cloud" or what ever he calls them now, boxes that he turns down a couple of times over about 6 months. A bit extreme, but the lids have about a 3 to 5 second "drop" as in pick them up by the lid and that is how long it takes for the bottom to drop off. About 1 inch tenons.

robo hippy