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Author Topic: Too Much Bow?  (Read 1867 times)

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Offline MSU_Keith

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Too Much Bow?
« on: May 06, 2005, 03:15:45 PM »
I'm planning on constructing a frame later this year or early next year.  In the mean time, I am prepping the land, including putting in a driveway.  Two bowed trees are in the way:



Both are white oak, 18"-20" DBH with a fairly straight run to about 18' up.  Although I can get a straight log from these, will the tension in the wood be to great for major frame members (assuming they make grade)? How about shorter stuff like braces?

I was planning to buck these to a length usable for frame members, end sealing and leaving till I can get a sawyer in to cut these along with the rest.  They'll have to sit till the driveway and clearing is done.  Any advice is appreciated.

Offline Timber_Framer

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Re: Too Much Bow?
« Reply #1 on: May 07, 2005, 10:54:07 AM »
mEven though the those trees look straight up to 18' or so the grain will be uneven. The tree wants to grow straight so the "uphill" side will have very tight rings while the other side will have far larger rings, making it impossible to cut a boxed hartwood beem.
I've seen this even in very straight trunked trees growing on the sides of hills, they ended up firewood.

Perhaps you could cut smaller beems out of the tight side of the log...I have never done so.
"If people concentrated on the really important things in life, there'd be a shortage of fishing poles."

Offline MSU_Keith

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Re: Too Much Bow?
« Reply #2 on: May 10, 2005, 08:43:21 AM »
T_F, thanks for the reply - I kind of suspected this would be the case.  As a follow up - is there any general rules regarding how 'boxed' the heart has to be?  Does it vary by frame member?  Thanks again.

Offline Timber_Framer

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Re: Too Much Bow?
« Reply #3 on: May 10, 2005, 06:02:00 PM »
Jim can answer the Does it vary by frame member? question better then I. I would presume part of the answer would depend upon whay style of frame you're building. The wood in a post on a simple cape I would imagine are less critical then say a high p[osted cape where the roof load is pushing out against the posts more dramatically. Also I don't recall using many BHW timbers when cutting braces.
Now while boxed heart wood is desireable for use in building frames but I have to this day not built a single frame building entirely out of boxed heart wood. You place an order with a mill and they saw it up and deliver your timbers and they are certainly not ALL BHW. You get what they send you. I have declined a few timbers because they resembled bananas, but not because they were freeof heart or center-cut.
I think the difference may not be so much how strang the wood is but how it checks and shrinks.
"If people concentrated on the really important things in life, there'd be a shortage of fishing poles."

Offline ARKANSAWYER

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Re: Too Much Bow?
« Reply #4 on: May 11, 2005, 03:39:42 PM »
  Not all timbers have to be staright.   I select trees that may have a natural bow like the ones in your photo for the chords in King Post bents.   Also some times I put them in as second floor beams with the natural bend up and the weight of the floor will flatten it out some.  It never hurts to saw them out and see how they lay.  You can cut them into boards if they bow to much for use as a timber.


ARKANSAWYER

Offline Jim_Rogers

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Re: Too Much Bow?
« Reply #5 on: May 11, 2005, 09:27:15 PM »
Boxed heart means box the heart, regardless of the growth rings, or the place in the frame that it may end up. There is no difference based on frame location that I know of.

Like Arky says, mill it up and see how it lays. If it has stress in it you'll see it as you mill it. The boards will lift or shift off the cant as it's being sawn.
If the tree or log has a bow in it, cut it short, and make several shorter timbers. Use them as posts, or if they have a crown use them with the crown up and the weight of the floor or roof will straighten them out.

Good luck and let us know how it comes out.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension


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