Small Tree/Big Tree

[Randy]

For education here, I want to hear your input. If I am cutting some 2x8's say, if I cut them out of a small PINE that squares 8"---compared to cutting out of a Large PINE that square's(alot bigger :D), would there be any difference in the strength of the wood??? Thanks Randy

[Tom]

The first 3 to 5 years of a trees life, or the the first 3 to 5 growth rings around the pith are made up of immature wood.   This is not as strong as the wood in the rings which follow.  The very center cut  of any tree may be the most stable, but not the strongest.  The smaller log that you describe will be easier to keep the grain centered because you don't have much option.  The larger logs will have boards that come form the side of the cant and may not be as stable as the boards that come from the center of the cant. 

Example.

If your cant is 12 inches wide, it will produce (3) 2x4's across its width.  The left one may crook and twist to the left. the center one may bow, but will be rather straight because the tensions are equalized on either side of the centered grain.  The right one will crook and twist to the right.

As you approach the middle of the cant so that the center 2x4 holds the pith, then it will be the most stable of all, though it will contain mostly wide grain and immature wood.

The side 2x4's will lose their tendency to twist because the grain will be near vertical, but they will have a strong tendency to crook toward the bark edge.

Strength also has a lot to do with how the board will be used. Flat-sawed wood is stronger across its narrow surface where-as vertical grained wood is strongest across it's wide surface.

(per inch...)
A flat sawed 2x8 is strongest when stood on edge, as you would do if you used it for a joist.
a Vertical Grained 2x8 is strongest when laid flat, as you would do for the deck of a floor.

[raycon]

I'd think close to the same ring density,knot density and MC you'd be pretty darn close to the same physical strength properties if the 2 trees were milled into 8x8's initially. 
A rule of thumb (don't know if it still applies) is look for  softwood with 6 growth rings per inch or more. The  idea being the more slow growing late wood present the better.   

[Ianab]

Remember every large log has the original small log inside it still.
The same wood is still there, just it's now surrounded by layers of new wood.

I'd guess there would not be enough difference in strength to worry about, natural variations between trees and defects would make a bigger difference.

Stability may be another issue though?


Ian

[woodmills1]

If the small trees were grown in a place where they were in close competition they may have more rings to the inch and actually be stronger.  I know its not PC but we call them pecker poles and I get some nice material from them.

[GHRoberts]

The smaller diameter tree should have more knots and grade lower.

[ARKANSAWYER]

   When sawing 2x stock I use the "again half rule" when sawing.  What this means is I saw 2x8's from logs that are 8 inches plus 4 inches (half of 8.) so I cut 2x8's from about 12 inch logs.  2x6's come from about 9 inch logs and 2x12's come from about 18 inch logs.  It will produce on average the best and stable lumber.  The 2x4's you buy at the store came from trees that were no more the 5 inches wide to begin with.
  This is what Tom was talking about and is the wrong way to cut 2x4's.  I did this to a customers log after I warned him but it is what he wanted and I saw for them.

  It would have been best to saw 2x8's or 10's and left it at that.   Small knots are not a problem and try to center larger ones in the center of the flat face.  Spike knots make the lumber weak.

[Randy]

Arkansawyer----Mercy I am confused. What if I only have 20" or 30" logs and want only 2x4's?? How should I cut them? When I custom cut for a customer-----they want what they want. Randy

[Ianab]

Hi Randy

The large log will usually be simpler, lots of straight grained wood away from the pith. With the swingblade of course you just start at the top and take 4x2s till you get to the bottom slab.
Flat saw the 4x2s like Arky says so that any knots will be thru the wide face. The 4x2s may have a tendancy to bow as they dry, but proper stacking will contol that. Once dry they should be superior to a board from a small tree or one containing the pith.

Cheers

Ian

[ARKANSAWYER]

  In large trees I make opening cuts at 4 inches so I get 4 2x4's but after that you will not make good 2x4's except if you make a + out of the center of the log.  That means you will get some "pies" like in qsawing that you could then trun up and make 2x4's out of with some waste.  That may not be real clear and I do not have a photo and under the influance of drugs this may not help.
  The board needs to come centered over the pith and large logs should make large boards.  Cut them large logs into 2x12's and bring them to me and I will swap you 2x4's  ;D

[TN_man]

Ianab,
With the swingblade, do you switch between the vertical and horizonal cuts as you work your way down the log? Like you start out with the vertical cutting the 4" and the horizonal cutting the 2". As you approach the center of the log you switch to the vertical cutting the 2" and the horizonal the 4". Am I assuming this right?

[Randy]

Arky-------Tom---------You Pro's-----And whom ever knows--I think I got  this understood about the MOST stable boards being Centered with the heart of the tree. To be sure I understand, here is some examples--Some extreme, but just to make sure.  (1) If I look at the end of a 2x4 laying flat, it would be more "Stable" if the grain was equal/matched from one side to the other?? Extreme example here; (2) If I had a 20" sq. cant on the mill with the heart of the cant centered---and wanted only 2x4's----if I was to put a plus sign in the end, crossing in the heart---take a 8" cut off the top, lay it to the side then a 4" cut(2"above and below the heart) turn this up and cut 2" thick for 2x4's-------then when finished, put the other pieces back on cut 4"(2" above and below the + line) turn this up and cut 2" for 2x4"s---------This would produce the "Most" stable 2x4"s-----Am I right?? (3) Then I realize I could turn the 4--8" sq. pieces that are left up on a angle---like quartersawing and get a few more 2x4"s that would be stable, but not as strong because the grain is quartersawed unless I was going to use these laying flat, then they would be stronger than the others if they were also used laying flat-----do I have that understood?? I know this is a extreme example, but I wanted to make sure I understand. (4)OK---Now lets cut another 20" cant----this time I am going to make 10 cuts to end up with 10--2x20"s, would these be fairly stable?? (5) Now you know whay my next question is going to be-----if I let these 2x20's dry for a few months then put them back on the mill and cut them into 2x4's will they bow, warp, crook as bad as they would have if I had of cut them into 2x4's while green?? (6)Which would be the best if I am cutting for myself and only need Stable 2x4"s-----Cutting it as described in the beginning would produce app 30 2x4's---18 cut in the "Plus" method with 12 more cut like quarteredsawed----------cutting the 20 2x20's or just cutting the 20"sq cant will produce 50 2x4's-----Which I will lose some if they warp to bad??  Keep in mind I am cutting mainly yellow pine for myself and I have 2 buildings I am going to build in the next 2 to 3 years(a 1300sqft Cabin and a 1000sqft "cook house") which I hope to cut ALL the material to build----------Just want to do it right and When I cut for customers I want to know enough to be able to give them the best advice-----------so all of you Pro's advice is GREATLY appreciated. If you have time --Please give me a reply to the 6 questions. Thanks Randy

[Ianab]

Ianab,
With the swingblade, do you switch between the vertical and horizonal cuts as you work your way down the log? Like you start out with the vertical cutting the 4" and the horizonal cutting the 2". As you approach the center of the log you switch to the vertical cutting the 2" and the horizonal the 4". Am I assuming this right?

TN

You can do it that way... But I normally saw softwoods by taking the first 1/3 with 4" cuts flat and the 2" vertical. Then swiching to 4" vertical / 2" horizontal for the middle part. This is more to do with knot placement in the boards than stability, trying to avoid spike knots. With a hardwood log or a mostly clear log the reverse may be better. The other guys are correct about different methods to get the best boards / best return from a log. But if you only have certain logs and only need 4x2s, you just have to make the best of it.

Cheers

Ian

[Tom]

Randy,;

Don't make it too difficult.  You have the idea grain wise.   

The picture that Arkansawyer posted is representing a way of cutting that is done everyday.  The big computerized mills will even do it.


You try not to split a cant in two so that the pith is split.  You aim for the bulk of the boards having the grain centered.  Anything that you get off of the side lumber is handled as best as you can.

Don't think so much about what you are taking off of the cant, Think of the faces you are opening up as you saw through the log. Optimally, it is that face that determines the width of the next board.  It's difficult to custom saw using optimums though.  If the customer wants 2x4's then giving him 2x8's isn't going to get it.  If you are sawing for maximum output from the log, then can cut all types of stuff.

Keep in mind that the pith isn't always in the middle of the log.  The log may have limbs (knots) that will make weak construction material if placed in a board improperly.  Tight knots should be encased, but that isn't always possible. Open knots (those on the side of the board) can still be used if the carpenter knows how.  Sometimes, as a sawyer, you just can't help but make inferior boards.  You just have to do the bestl you can with the tree that is provided.   It's that "silk purse from a sow's ear" thing, you know. :D

If you get a chance, go to the lumber yard and look at a stack of 2x4's.  Preferably find a stack that lis still banded.  You will see were the tree was cut  to produce all 2x4's.

You will see that 2x6's and larger are usually cut with the grain centered.  that means that there is side lumber that isn't accounted for in the stack.  That side lumber probably ended up as 2 x 12's or something like that.   Your customer will want it split.  You need to be able to tell him what will happen if you do.

[UNCLEBUCK]

Can I tell how I saw a 20 inch square cant on a circle mill to see if I should improve on anything ?  I just saw 1 inch boards until I get sick of 1 inch boards like leaving a cant of 12,10,8,or 6 inches thick and the flip the cant 90 degress and saw the rest up into 2x stuff .  If I needed all 2x4 boards out of that 20 inch square cant I would just begin sawing 2x from the beginning down to the dog board or (last board) then run them 2x20 inch boards through the edger , I always automatically get some flat sawn from each side of the cant and some nice quarter sawn stock towards the center . I cant think any more than that or else I would have a brain warp .  My problem is having someone watch me saw standing there wanting this and that . They get whatever I come up with but I try to give them alot of a certain size after they leave so I always say to drop off your logs and give me a few days and I will call you right away when I am done , I always saw them right away and stack the boards in the shade close by . I never know when I get a breakdown so I always say a few days. This is interesting topic :P