iDRY Vacuum Kilns

Sponsors:

Logs too big for boxed heart

Started by Engineer, November 26, 2003, 08:11:32 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Engineer

I have a dilemma that maybe some would envy.  I have a logger cutting white pine for my new timber frame, and some of the logs are 32-40" dia. at the small end, 16 feet long.  I think it's a tremendous waste to mill off boards until  I get down to an 8x12 or 8x8, as I have no use for that much thin lumber (or even 8/4 or 12/4 stock) and no market for it.  

Is it Ok to cut free-of-heart beams, maybe 4 of them, out of one log, or will I encounter problems with warpage and checking?  or should I just mill off 8/4 stock for flooring and be content with one beam per log?  ???

Minnesota_boy

I'm not an expert by any means, but I think that white pine is stable enough that you can cut free-of-heart beams without warping.  If those trees were hardwood, then it is a bit different.  I've sawed beams like you propose and haven't heard of problems with them.  
I eat a high-fiber diet.  Lots of sawdust!

ronwood

Minnesota_boy,

I am cutting beams for a pole barn. I have white oak that I will be using for the beams. Like Engineers they are large logs 30 in + and I would like to cut more than one. I was thinking of removing the heart and make my starting cuts about 1 to 2 inches from the heart resulting  with a beam on each side of the heart. Do you think that that would be good enough for a pole barn. Checking for me is not an issue. I will be installing them green.

Jim_Rodgers what are your thoughts. I would be cutting simular to the diagram in the thread  "Boxed heart beams or not?"  positions 3 and 9. Size of beam would be 6x10 or 6 x 12.  16 ft. long

Thanks for the help.

Ron
Sawing part time mostly urban logs -St. Louis/Warrenton, Mo.
LT40HG25 Woodmizer Sawmill
LX885 New Holland Skidsteer

Minnesota_boy

I think you will find that the white oak will bend.  I haven't experience with the white oak to suggest how much it will bend though.  It might still be acceptable to you for that use.  Maybe someone from places that have large white oak can tell you how much it will bend.
I eat a high-fiber diet.  Lots of sawdust!

Jim_Rogers

Engineer:
One rule for milling timbers from logs is that you should box heart timbers when they are 5"x 5" or larger.
So, I interpret this rule to mean that if a timber is a 4"x6" or a 4" x 7" that they can be milled "free of heart".
Now this interpretation has come back to bite me in the butt, as some of my 4"x7" have warped to the point where they can't be used.
I'd try to take a large log and cut some other pieces for your frame off the sides of the intended boxed heart timber.
Look at your stock list and see if you can get some 4x7's or 4x8's of the sides of these 8x10s or 8x12s. Maybe even some 3x5's or some other part from your stock list, even if this side part is longer than the needed one for the frame stock list. If you put this side timber in the pile and it warps and it's extra long maybe you can still get some thing out of it later by cutting it shorter.
If these larger logs are good grade and you can make other timbers off the side, you could take the chance to make more than one timber per log, but you won't know if this will workout until later when you go to use them.
Some information you need to consider before milling "free of heart center", (FOHC) beams is how long between milling them and cutting the joinery and erecting the frame.
If it's a long time there is a chance these FOHC beams could distort while in the pile. If it's a short time then it's not as likely.
If these large logs are high grade logs you could look at selling the high grade boards or planks, from your milling operation to help pay off the milling expenses. After you have filled your stock list with all the needed lumber for your frame, such as boards and or planks. You've stated that you don't have any market for them. Well, that's just that you don't know of any market for them. There should always be a market for them somewhere near you, that you've just not found, yet. Spending the time to find this market could be a problem.
You mentioned the logger, where does he sell these type logs if not to you? Does this other buyer have a market?
Placing a few phone calls could find these markets, or if they say they don't want it, ask them if they know anyone who would want this side lumber.
If these large logs aren't high grade you should be careful where you use them in your frame, and try and use the boxed heart beams where the strongest timbers are needed.
As each frame is a unique design, there maybe places where you can use these FOHC beams and they will be OK.
Good luck with your project.
Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Jim_Rogers

Ronwood:
I haven't had any personal experience with white oaks of this size.
My experiment was with white pine and that log has some stress in it, causing the 6x6 beams to move.
You can try your experiment and see how it comes out, but you're assuming the risk if they do warp.
Again you have to know the facts about the frame. You've said it's a pole barn and you don't care about the cracks, but what's the timing?
Can you mill them and install them right away? Before they have a chance to "take off" on you? Some take off as you mill them, if they have stress in them.
There are lots of things to consider when you make these decisions.
Anything that I say would be just guessing as far as will it work for you.
Good luck with your project, and let us know how you make out. If it works or not.
Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

IndyIan

I think I've read somewhere that sapwood shrinks alot more than heart wood.  So if you could cut your beams free of heart and free of sapwood you might have better luck with straighter beams.
Also you could have the logs cut so you get at least one beam with boxed heart.  Like this:
 /  B  \
( BBB )
 \  B  /
This might be hard to do on a band mill, I think a swing mill would do this no problem though.

Using the beams green, quarter sawn(like in my picture) and orienting the beams so any potential bowing is in your favor I'd think you'd be ok, or atleast done everything you can.

I don't know what the early settler's did in their frames. I can't see them whittling down huge trees to box the heart but they may have, next time I'm in an old barn I'll have to look.

Good luck!
Ian

Engineer

Thanks for all the helpful replies.  I can easily get an 8x12 or larger out of each log, and probably surround it with six 4x8 joists.  Since I need over a hundred joists, and only about 16 8x12's, that will work out fine.  Some of these logs are a full 40" diameter, if I cut them right I can get what I need without a lot of waste.

A friend told me after I posted the original message that he needed 2500 bf of thin stock for board and batten siding on his new shop, so I guess I have a home for the excess after all.  I am going to need 8/4 stock for the T&G flooring too, which I was going to buy.  I have enough logs to make most of it.

Jim_Rogers

I'm glad you've figured out a use for all that side lumber.

What size and or type mill are you using to mill these large logs?

Jim Rogers

PS. Early settlers picked trees that would produce a log that was just over the size of the timber they needed. That way they didn't have to hand hew that much off the log to "square" it up.
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Engineer

Using a Wood-Mizer LT-30.  I told the logger that I wanted the longest logs to be just over the size of the beam, so that the handlig would be easier.  That way, I can cut multiple small pieces out of the bigger and shorter logs.

Jim_Rogers

If you take a framing square and measure with a tape from the 8" mark on side to the 10 or 12" mark on the other, across diagonally you'll get the diameter of the narrow end of the log you'll need to produce that beam.
I use my stock list to create a log list, using this method, to give to a logger so that he can cut or produce the size logs I need to make a frame.
From the log list you can estimate the lumber produced over the timber sizes to see if you'll have enough boards or planks for your project. That is of course if he fills the list to the sizes you've listed. Most of the time I state the log list as so many logs at xx inches or larger by 16' for example. That way you might get logs a little larger then what you need to insure that you don't get any round edge timbers.

If you have a pile of logs, already cut, then as they come to the mill, check the diameter inside the bark on the narrow end and see what size timber this log will produce based on the diagonal of your timbers. That way you'll make the largest timber needed from the correct size log.

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

ronwood

Jim_Rogers,

I think I am going to cut 2 x 12  and reconstruct the beam that I need. Doing it this way I can put it back together with the hope of minimizing bending and twisting.

I will be cutting and installing the beams in the next couple of weeks.

Do you see any problems with this?

Thanks
Ron
Sawing part time mostly urban logs -St. Louis/Warrenton, Mo.
LT40HG25 Woodmizer Sawmill
LX885 New Holland Skidsteer

ronwood

Ian,

I would be able to cut the beams in your illustration with my mill. Has I stated in my previous post I think to Jim_Rodgers I think I will cut 2x12 and reconstruct the beam for my pole barn.

Thanks for your assistance.
Ron
Sawing part time mostly urban logs -St. Louis/Warrenton, Mo.
LT40HG25 Woodmizer Sawmill
LX885 New Holland Skidsteer

Jim_Rogers

QuoteRonwood:
I haven't had any personal experience with white oaks of this size.
There are lots of things to consider when you make these decisions.
Anything that I say would be just guessing as far as will it work for you.

I had a customer who wanted me to mill up some 2x10's for a header for his horse run in shed. He was going to nail these two 2x10's back together after I cut them in two. I really didn't see the sense in that, then. So I left it as a 4 1/8x 10 and he installed it that way.

It's a lot of extra work to mill them and then nail them back together again, especially white oak.
It's an experiment in building that I can't comment on, other than saying I think the wood is stronger if it's left whole. But if it bends what can you do with it? If you have an alternative product you can make out of the bent 6x12's then I'd try it and see how it comes out. They've got to be stronger than three 2x12 nailed back together.
But again I don't have the experience with that size white oak, and the risk is yours.
Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Buzz-sawyer

Hey Jim..
In the construction trade we learned that seperate boards nailed together were stronger because...any defect that may be in a single piece will not run through the beam at the same place...now this applies to boards cut from different cants obviously...also crownig and twist are minimized as well the stresses in different boards work against each other when nailed up....strongest yet...with plywood sandwitched in between boards
Don
    HEAR THAT BLADE SING!

ronwood

Buzz-sawyer,

How thick of plywood wood you need to sandwich between them? Do you add the plywood the full length of the beam.

Jim,

Thanks for your input. It would seem like one full size beam would be stronger if it did not have any defects in it. I going to see if I can get enough logs to box the heart on the beam. Not sure that I have enough logs ofd the length that I need.
Will let you know how I go.
Sawing part time mostly urban logs -St. Louis/Warrenton, Mo.
LT40HG25 Woodmizer Sawmill
LX885 New Holland Skidsteer

Jim_Rogers

I was right in the middle of typing a response and the power went down. :(

Must be because of the big wind here in Ma today.

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

Jim_Rogers

Buzz:
I told my customer, the one with the horse run in shed, about that idea/method of nailing and gluing a piece of plywood in-between the two 2x10's, but he didn't want to do all that work.
I had heard that before at several different times, but most say that any length over eight feet long that it is not that strong due to the length of the plywood. His span was 16'.
In Ronwood use, vertical in a post, this could be a good solution, as the seam between the two pieces of plywood shouldn't matter that much.
Ronwood, I though you had some large logs to use and you didn't want to box heart the beam. If you can box heart them then they should be OK to use for poles.
Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Don P

I agree with Buzz on the distribution of defects in built up beams...you'll find almost his exact wording in the Wood Handbook, distribution of defects. Glulam beams take advantage of this in the horizontal, in fact they use the best wood as the outermost plies where the most strength is needed and the lesser grades in the middle plies...kinda the same as necking in an I beam where the strength required is lower. My understanding is that plywood doesn't add any appreciable strength to a built up beam.

FOHC checks less than boxed heart, way less. A boxed heart is guaranteed to check, I've seen more than a few FOHC timbers that didn't check. I'm not trying to push one over the other just pointing out that different cuts have different attributes. Sometimes its better to use one, sometimes another. Juvenile wood on one edge of a FOHC is probably the worst culprit for bowing a timber. Juvenile has lengthwise shrinkage sometimes 10 times greater than adjoining wood.

Ron W has built a calculator for telling how big a log is needed for any timber dimension you punch in.

Engineer

I'm finding that in looking at the ends of the logs, the sapwood in the pine is very evident - it is oozing and a much lighter color than the heartwood.  Is that what you are considering juvenile wood?  If so, I have no intention of incorporating the sapwood in any of my beams.  It will all be taken off for thin boards.

I hope you're right about FOHC being relatively check-free, as well. It looks like a lot of what I will be cutting will be FOHC and exposed in the final construction.

What I need to know now is how much the wood will shrink during the drying period.  I will be starting to cut next weekend, and most of it will be sitting in a pile until about April.  Do any of you think that the pine cants will shrink appreciably during that four-to-five month period?  I was told by my framer to cut them 1/4" oversize, for planing, but I'd be willing to bet that's not enough.  Any opinions?

Don P

No, Juvenile wood is the first 5-20 years growth...the very heart of the tree. This wood needs to be flexible, fast growing and springy to take on what mother nature dishes out before the tree is bulky enough to take it by sheer dimensions. Unfortunately it shrinks lengthwise much more than later wood. As an example many of you have probably seen or can start looking for, look at southern pine 5/4 decking. I seem to run into alot of juvenile heart in this. It often bows tremendously and sometimes you can see crosswise breaks in the juvenile wood. This is where the mature wood won't let the board length shrink but the juvenile wood shrinks till it breaks. I've seen it in some of the finer studs out there too, look around the pith.

If I were sawing FOHC I would stay closer to the outside of the tree than the inside, then box the heart, then grab another timber off the other side. Will they bow? quite likely. Will they check? less likely. Thats what I mean by appropriateness for the situation. Sometimes one is more important sometimes the other. If both then glulam  ;D. Almost all wood movement happens between 25% moisture and final moisture content...you won't see most of it till its in service, I've shed dried 6x white pine in 2 years to around 15%.

Look at a chunk of firewood, the star shaped radial checking is typical for a boxed heart section. Now split into quarters, see how the checking is less and imagine how the drying stresses work in the wood, radial shrinkage is half tangential...see how you just relieved the tangential section?

This is a link to a shrinkage calculator.
http://www.woodbin.com/calcs/shrinkulator.htm

Fla._Deadheader

Fine job splainin that, Don.  Thanks
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

Jim_Rogers

Engineer:
How much over for planing depends on who's doing the planing or more like how they are doing the planing. If you're planing by hand then that could be OK to be 1/4" over. If you're intending to send them out to a shop that has a four sided planer, you should check with the shop. My four sided planer company wants them 1/2" over final size as the four sider takes off 1/4" on each side.
Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

ronwood

Jim_Rodgers,

Cut my post for the shed last summer and I was able to box the heart on them. They look pretty good.  On the headers I decided to use two 2 x 12 (full thickness) post oak for headers. I am going cut a notch on each side of post for the 2 x12 to sit on. What I am conerned about is since I using green lumber off the mill how to I attached them to the pole & account for the shrinkage that will occur as the headers dry?

Thanks
Ron

Sawing part time mostly urban logs -St. Louis/Warrenton, Mo.
LT40HG25 Woodmizer Sawmill
LX885 New Holland Skidsteer

Jim_Rogers

Ronwood:
What size are the posts?
Jim Rogers (no d in my name, thank you)
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Thank You Sponsors!