Cutting Timbers for Timber Framing?

[Woodbender]

Okay I am fully prepared to be confused.

I'm not looking for which saw is better, band versus swing.  I'm needing to understand how to cut sizable framing timbers from a log.  I have heard "avoid heartwood" completely.  I have heard "if you can't avoid heartwood completely then box it in entirely".  I suppose those two statements are not mutually exclusive are they?

Is there a simple diagram some place for cutting Oak or other substantial framing wood found in Michigan.  (maybe the Michigan boys can chime in with other prevalent Michigan species suitable for framing)   Of course I realize this depends almost entirely on the girth of the log.

I imagine a beam or post with heartwood along one side might have it bow?

I will be cutting framing timbers as well as siding, but primarily I am curious about proper timber cuts that won''t warp on me after they've been fit up and jointed.

Thanks - and BTW this is a awesome place to hang out!

[logwalker]

Welcome to the forum. Maybe this is a better question for the timber framing forum just down the hall. I know it crosses into both areas but they have the experts on what is needed. Sit tight and maybe one of the administrators will relocate it. I am fairly new here as well. So what is it you are thinking of building? Joe

[ohsoloco]

Check out THIS THREAD

Boxed heart beams are definitely the way to go.  I use free-of-heart timbers for things like braces, since they'll be cut so short. 

[Tom]

The goal is to produce a beam that resists warping.

By boxing the heart (pith) your are keeping the growing stresses equalized all the way around the beam and it will stand a better chance of drying straight.

If you cut one Free of Heart (generally meant free of pith) it will bow or bend.  It's just the way wood reacts to havling its growth stresses released. 

Heartwood and sapwood are different and can cause some different movement in a board or beam as well.  But, you really have to determine what the person is speaking of when he is saying "heart" because some folks use the word heart to define pith and some people are talking about the heartwood, which is a different animal.

There are very few trees that will produce beams "free of heartwood".  Sawing "free of heart (pith)" just requires a large and straight log.

[Don P]

This is free of heart Dougfir beams. I've used more than a few good straight ones through the years. My woods do not produce such timber though. FOHC carries higher design values in a few cases and can grade higher. It tends to check less and bow more.


Cutting free of heart has merit but is far more likely to result in an unuseable timber. Or as ohsoloco pointed out, at least at the length you wanted.
If you can get out of the juvenile portion of the heart it helps, these first 5-10 growth rings were laid down by a young, supple tree. This wood shrinks lengthwise and where release of growth stress is immediate at the saw the lengthwise shrinkage of juvenile wood happens as the timber dries.

This picture shows a decking board ripped right down the pith. Notice the crossways breaks in the first few growth rings. These younger, weaker cells shrank lengthwise but were restrained by the surrounding wood and nails, finally checking. Unrestrained the same forces on the edge of a drying free of heart timber can bow it.



Boxed heart is much more commonly accepted, is more likely to stay straight, but because of drying stresses is more likely to check. I wouldn't personally grade a boxed heart timber for myself higher than a #2 because it contains more internal unknowns.

As usual there's as many opinions as people you ask 

[fat olde elf]

I have produced boxed heart beams of red oak, white oak, and pine up to 12X14 inches with very little bow or deflection.  Several of these were over 24 feet long and came out of the destruction from Hurrican Hugo......Most are now in my workshop addition..........Looking Good !!

[Brucer]

Most of my work is for a timber framer (sawed him 55,000 BF of Douglas-Fir timbers last year). He buys the logs and I saw them to his specs.

When the specs say "Boxed Heart", I try to centre the pith, but I'll shift it an inch or two off centre if it will give me better yield.

When the specs say "FOHC", I saw out a 2" board containing the pith. That keeps the early growth wood out of the timber. Douglas-Fir doesn't bend much when the stresses are released, so that isn't usually an issue. The large butt logs in D-Fir usually have a fair amount of sweep, so I have to be careful to get the sweep exactly in the plane of the piece I'm sawing out. I keep a red crayon handy and draw a line across the end of the log to mark the plane of the sweep -- it's hard to keep track of it once the cant is squared up (especially when you've got a memory like mine ;D).

I've had to saw some FOHC Western Red Cedar, and that's a whole other story. That wood moves when you saw it off centre. The only way to deal with this in longer timbers is to saw the cant an inch or two oversize and then saw out the centre. Then take each of the now-curved timbers and saw off the faces to get 'em straight.

I don't charge extra for sawing FOHC, but my customer certainly charges more for the timbers. He has to pay a premium for those large diameter logs, and the 2" piece with the pith in it is usually waste -- those boards will fall apart when they dry.

If the customers don't specify, they get boxed heart.

[snowman]

Iv'e been stacking post and beams like crazy since last fall.Iv'e done my best to box the hearts but sometimes it's easier said than done,I'm new at this though.Most of my stuff is beetle killed white fir from property i'm moving to and larch from land i now live on. The white fir beams get me raised eyebrows, the larch I'm told tends to twist.I have lots of stuff to build, my house,sawmill house, barn, power house root cellar etc. Im just cutting tons of beams and hoping for the best, ill use the cream of the crop in the house, the culls in the root cellar and the inbetween stuff on the rest of my projects.Nothings had time to dry yet, I hope thngs go well.Wish me luck. :-\