Milling Branches

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Yellowbeard

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There are some huge branches on the white oak I am milling (see other thread). I was hoping to mill them to make some stair treads that will be around 12"X4"X36". However, I have been advised (and now also read) that milling branches is not wise due to the tension that can be in the branch causing the final product to warp.

Does anyone have any experience with this? For what it's worth, these branches are HUGE (but that may just mean more tension).

Thoughts?
 
Yes, I'd agree there'd be uneven tension after milled, even if the branch as a whole has aged/dried already. I'm more familiar with softwoods, but the branch wood I've worked with tends to be more dense on the upper side since the rings grow off center (gravitational load puts the center closer to the top side of the branch). This gives uneven pressure dynamics that will easily change when the rings have rip cuts.

Whole branches stripped of bark can make great decorative elements (without a rip cut through them they usually keep their shape OK), but I wouldn't use them for main support or where precision is necessary. As soon as slicing through with a rip cut, they usually curve/warp to some degree, and over time I've seen this warping often increase.

But as mentioned, I can't say so much for oak/hardwood, nor for "massive" old growth branches. But if the rings look well off center, you may want to reconsider.

(edit: I just changed this to say the rings grow denser on the "upper" side, as I originally said lower by mistake)
 
There are some huge branches on the white oak I am milling (see other thread). I was hoping to mill them to make some stair treads that will be around 12"X4"X36". However, I have been advised (and now also read) that milling branches is not wise due to the tension that can be in the branch causing the final product to warp.

Does anyone have any experience with this? For what it's worth, these branches are HUGE (but that may just mean more tension).

Thoughts?

Hi, I would mill them for sure. But when milling a branch, I would always cut it vertically as it was on the tree vertically. Meaning, don't cut the branch horizontally or 90 degrees from where it was vertical when on the tree. If you do, the stresses will make it bow/warp alot when it is free as a thin board. Now if it is cut vertically in slices, those stresses are still there but they have to fight the stiffness of the board to make it bend. Stiffness is proportional to height cubed, so comparing say a 1" thick board cut horizontally to say a 10" wide board (and also 1" thick) cut vertically the 10" height can resist the stresses much better than the 1" by an order of magnitude. In the vertical cut, the residual stresses have the 10" of height to resist the bending, whereas the horizontal cut only has 1". You'll still get some movement as it dries, but not that much if cut vertically in the slices (with the minimum movement in the "leave whole limb alone while it dries" 10 years in above comments, which would be the maximum possible stiffness but take a long long time to air dry it). I like cutting it green though as more of those residual stresses would be released during the drying process and allowing some bending then vs. the stresses still being "trapped" in the wood more if left as a full limb to dry, only to want to bend the wood more when cut after dry. If you can't tell from the limb once cut, mark it first what was vertical when on the tree before milling it later. Note limb wood also needs good end treatment as end cracks are more likely than trunk pieces, however you do it.

Now if you are not planning to ever joint/plane the wood after milling, you may still not want to do limbs as you will get more movement than the trunk part of the tree. But if you joint/plane later as I do, I don't care much if it moves a little as it will become planar after those processes anyway. Chainsaw milling is not so precise or accurate as band saw milling and is wasteful of kerf anyway, so I don't worry about a little extra waste in the process. It is what it is. I view chainsaw milling as a "green" process to not turn trees into firewood or waste, and in a sense, more "green" than bandsaw milling as you can mill the whole tree if you want to and all the weird bends and shapes and such otherwise discarded. (But there is that thin bandsaw kerf, so that is pretty green too for what it can do). Either is green vs. letting the wood rot in the woods untouched and put to good use! - Paul, Mechanical Engineer on the side
 
Is there an easy way to tell which way they were oriented while still on the tree after they've been cut off? I've already cut them and rolled them around so I am not sure which way is up in order to follow your (excellent) instructions.

Thanks!
 
Look at the rings. The center would be closer to the top, so tighter rings are the top side, the widest rings would be the bottom.
 
Look at the rings. The center would be closer to the top, so tighter rings are the top side, the widest rings would be the bottom.


Wow. I feel stupid. You already said this up-thread and I totally missed it. Sorry. Thanks.
 
And if you or anyone tries this sort of thing, please post back for the forum the results after dried/final cut. No guarantees here. I'm drying my own now but not there yet. But I'm experimenting with better end checking treatments too at the same time, so there will be "confounding" factors in my experiment. The more forum members who can report back on results of trying things the better! - Paul
 
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