# Internal Stresses



## djg (Dec 24, 2009)

I'm pretty sure I've asked this before,but I guess I'm a little thick headed. Someone on this forum or another forum recently was asking about milling walnut logs. Sorry, but I couldn't find the post. They were asking about having the large branches milled too. Someone else responded that they wouldn't recommend it because of the high internal stress in the branches would cause the resulting lumber to distort too much to be usable. If this is true, wouldn't a log (trunk) of the same diameter have the same internal stresses. I question this because lack of available equipment, I'm limited in the size of small logs I can collect. Am I wasting my time salvaging smaller logs (12-16" dia. range) than what you sawyers would normally do? I've seen others here that post about logs of similar size to the ones I've collected and just am wondering how their lumber turned out (stability).
If the stresses in log or limb lumber are essentially the same and that they really don't effect the wood's movement, then wouldn't it be prudent to keep large branches of the dia. stated (especially say walnut or cherry)?


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## Daren (Oct 14, 2006)

djg said:


> If this is true, wouldn't a log (trunk) of the same diameter have the same internal stresses.


No because a trunk is growing straight up (in most cases, you can have stress lumber in a "leaner" trunk too). Whereas branches are growing out horizontally and that is where the stress comes in. They are basically stronger on one side to fight gravity. When cut apart (milled into lumber) that stress is released and you get lumber that wants to curl up on you. And too if you look at a cross section of a trunk vs a limb the rings on the trunk are concentric. The pith is in the middle and the growth rings (again in most cases) are equal all the way around. Cut a limb off and look at the growth rings, the pith is going to be off center and one side is going to have tighter rings/one side the rings will be further apart. This causes stress in lumber, growth ring orientation.


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## djg (Dec 24, 2009)

Very good explanation. I understand now.
Thanks


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## cody.sheridan-2008 (May 23, 2010)

Thanks Daren, I didn't know that either:thumbsup:


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## TexasTimbers (Oct 17, 2006)

djg said:


> . . . I'm limited in the size of small logs I can collect. Am I wasting my time salvaging smaller logs (12-16" dia. range) than what you sawyers would normally do? . . . . wouldn't it be prudent to keep large branches of the dia. stated (especially say walnut or cherry)?



Maybe you need to look at this whole potential treasure trove from another angle. Instead trying to process lumber, consider a use for it other than lumber. Those concentric ringed limbs make dazzling bowls, plates, goblets, candle holders, vases etc. Have you thought about getting a lathe? This won't solve your problem but it will allow you to utilize some of it until you can assemble some more efficient equipment to process lumber for your flat work passion. 

You might be able to sell some of your excess turning blanks on eBay or locally on CL also. I know this is a dramatic departure from where your focus is, but I'm just trying to suggest something that would make at least some use of your trees. I mean it's apparent that you have a great deal of determination and this would keep you in the game until you eventually get your lumber processing dilemma resolved. 

And who knows you might fall in love with turning.


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## djg (Dec 24, 2009)

TexasTimbers said:


> Have you thought about getting a lathe? ....
> 
> I mean it's apparent that you have a great deal of determination and this would keep you in the game ...


Yes I do have a lathe and have been playing with it until I had bandsaw problems. I've set aside a lot of firewood chunks to practice on.

As far as determination, I'm not so sure it is as much as it is for a treatment to my ailment. I think I caught the bug you guys talk about years ago. Someone here talked about the sound and smells of a sawmill that kind of stay with you. Like the smell of white oak or ash in the air when sawing a log. I wasn't the sawyer, just the grunt keeping the boards coming off a circle mill away from the blade. He wasn't much on teaching, that takes time and time is money. I just did the menial tasks like trimming the flitches (sp?) into boards and stickering. But some of the beautiful lumber that came off of that mill, it does stick with you. I still remember hit and miss planing some hedge lumber on the outside planer on a cloudless day. A stream of bright yellow dust shooting into the air against a bright blue sky. Sounds silly to remember things like that and not so much summer's heat while on top stickering an 8' tall pile in the sun.
Well, I gotten off track and I swore I wouldn't get long winded. Back to my treatment. The things I've posted about here, like my attempts at chain saw milling, etc, probably seem pretty ridiculous to most of you, but the things I try is the only way I can get my fix, and hopefully regain some of my sanity:laughing:. As far as my thriftiness, since my time at the mill, I just hate to see good logs go to waste. I can appreciate now what they can become and I end up trying to save more than I can handle, despite how ill advised it might be.
So much for not being long winded.


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## TexasTimbers (Oct 17, 2006)

djg said:


> . . . But some of the beautiful lumber that came off of that mill, it does stick with you. I still remember hit and miss planing some hedge lumber on the outside planer on a cloudless day. A stream of bright yellow dust shooting into the air against a bright blue sky. Sounds silly to remember things like that and not so much summer's heat while on top stickering an 8' tall pile in the sun.
> Well, I gotten off track . . .


You haven't gotten off track brother, and I'm not talking about your last post. 

I'm not Yoda but if I was here's what I might say:

_Be patient, you should. Reward you, it will._ :yes:


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## Streamwinner (Nov 25, 2008)

djg said:


> Yes I do have a lathe and have been playing with it until I had bandsaw problems. I've set aside a lot of firewood chunks to practice on.
> 
> As far as determination, I'm not so sure it is as much as it is for a treatment to my ailment. I think I caught the bug you guys talk about years ago. Someone here talked about the sound and smells of a sawmill that kind of stay with you. Like the smell of white oak or ash in the air when sawing a log. I wasn't the sawyer, just the grunt keeping the boards coming off a circle mill away from the blade. He wasn't much on teaching, that takes time and time is money. I just did the menial tasks like trimming the flitches (sp?) into boards and stickering. But some of the beautiful lumber that came off of that mill, it does stick with you. I still remember hit and miss planing some hedge lumber on the outside planer on a cloudless day. A stream of bright yellow dust shooting into the air against a bright blue sky. Sounds silly to remember things like that and not so much summer's heat while on top stickering an 8' tall pile in the sun.
> Well, I gotten off track and I swore I wouldn't get long winded. Back to my treatment. The things I've posted about here, like my attempts at chain saw milling, etc, probably seem pretty ridiculous to most of you, but the things I try is the only way I can get my fix, and hopefully regain some of my sanity:laughing:. As far as my thriftiness, since my time at the mill, I just hate to see good logs go to waste. I can appreciate now what they can become and I end up trying to save more than I can handle, despite how ill advised it might be.
> So much for not being long winded.


I know exactly what you mean and I appreciate your eloquence in describing milling. I also have only been milling on a very small scale but the pleasure is immeasurable. On the one hand, I love turning beautiful wood that was otherwise destined to be burned into something useful that I can give to another person. The sensory experience is quite amazing, too, particularly the smell of fresh cut wood (and the occasional smell of burned wood). One thing I would add is the anticipation and curiosity that overwhelms me when I get a piece of wood I've never worked with before or looks like it would have some interesting characteristics. It's quite regular for me to be walking around the neighborhood and see a tree, stump, or crazy knot and think, "man, I wonder what that would look like on the inside..."

Anyways, a few months ago I milled about 50 or so blanks from walnut logs that I got from a gentleman clearing out his orchard (I don't do any turning, but figured I'd use them for making toys, bandsaw boxes, and other small projects). At someone's recommendation I stored them in my garage attic after sealing the ends with green wood sealer. I checked on them earlier today and about 3 out of 5 of them popped open and the ends. Most of these were just single checks and it is hard to tell how far deep they went. I could hypothesize about several reasons this happened:

1. As Daren described, these were most likely branches and subject to additional undue stress.

2. The attic provided too much fluctuations in temperature and/or too high of a temperature for the blanks to dry evenly.

3. The ends were insufficiently sealed. I used a green wood sealer from Woodcraft and was advised by my neighbor to thin it with water which would make it easier to get in the crevices and pores.

4. The blanks were improperly milled. In many of the blanks, because the logs weren't very large (12-18" diameter), getting a good sized block required including the pith.

5. The checking was inevitable and the sealer likely prevented more checks from forming.

I've also milled a bunch of avocado logs, but stored them on some shelves in my garage (about three or four weeks ago). I noticed that some of these have also popped, so I could possibly rule out the attic issue. 

And, for what it's worth, I think that even the blanks that have checked are still quite usable.

-SW


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