Releving tension in soft woods.

[losttheplot]

Hello.
I live on a small island so I take what ever logs I can get, usually Doug fir.
Lots of them have tension in them, although the sweep mostly comes out when they are bucked.





I am cutting 1 x 8 boards on a Norwood 13hp band mill.

I am trying to get straight boards so I am following the advice in the forum extras, however they are still moving as I cut them.

Any advice on my cutting technique would be welcomed.

First I lay it on the bunks and level the heart end for end.
The wide part of the log is parallel to the bunks.
any sweep is horizontal.




Then I measure up 4 inches from the heart, plus 1 and 1/8 inch if I can get a flitch.





Flip it 180 degrees and set the cut at 8 inches plus 1 and 1/8th for any flitches.





That leaves me with an 8 inch flitch.





That I flip 90 degrees.





Then I level the heart and cut off the wane and maybe a flitch, this is where I would be cutting off the hump or the ears if the log is bowed..
This is where the stress is showing up.





The first board or two often have more sap wood on one side than the other, this is hard for me to avoid.
They move towards the sap wood.
Once I get into the heart wood there is 1/8 to a 1/4 of an inch movement over 12ft




The closer I get to the heart the less the boards move as I cut them, I am rotating the cant as I cut, but it is not lifting from the bunks.





I can live with the amount they are moving, but I am worried they will move more as they dry.

Thanks.

[carykong]

What are the boards going to be used for?

[Magicman]

In my opinion, your sawing technique is correct.  At least that is essentially the way that I would saw them.  I am not surprised that you detect some movement as you saw and stress is relieved.  That stress is in the log and you have to release it.

You may loose some lumber as it dries, but not much and not nearly what you would if you were not opening and sawing the log correctly.  Don't worry.

[redbeard]

Hello losttheplot looks like you have it figured out. If you flat saw the tight grain sap wood down to where it looks like your boxing the heart it can relieve some of the compression. I call those windtrim logs. You probably have a fair amount of wind like we do on whidbey island. Nice pics of your set up.

[rbarshaw]

The only thing I can suggest, is if it is going to be a problem, cut them wider than needed, then when they dry, trim them again. Probably not what you want to hear, but it may be the only solution.

[Tom]

You can relieve the stress but you won't make it go away altogether.   One thing you can do to help is not make such a deep slab cut.  That slab you show here might make a 1x6 if you take the time to do it and the extra cut will let you see where the log is going to go.  This is especially important when sizing the width of the cant.

Many stressed logs require turning after sawing each board.  The thinner the board, the less it moves.  If you are cutting 2x, or more,  material, everything contains a lot of stress.

If your board is moving, then the cant is moving also, in the opposite direction.  It pays to look under the cant on a band mill to see if the cant has daylight developing under it.  If it does, You might benefit from turning it.  

The more frequently the cant is turned, the less out-of-whack each board will be.  The movement might be on the ends or in the middle.

You are doing a fine job and have the idea down pretty good.  Just remember that the log is a living thing.  No matter what you do, you are not going to be able to saw it as if it were a piece of plastic.  It has a mind of its own.  That's why saw milling is an art.

Rbarshaw has a the answer for those boards and cants that move a whole lot.  Sometimes your only salvation is being able to come back later and edge the dried lumber into a straight piece.   That might require that the board be cut 1 or 2 inches "fat" in the beginning. It's just hard to second guess that kind of thing.

[redbeard]

Have these logs been down a long time? Sometimes when they are windfall logs that have been down in the woods for a few years can be hard on blades. Doug fir is the most exspensive to saw for me. But I love the strength and beauty of the boards.

[Larry]

(Image hidden from quote, click to view.)

From that off center heart I would be thinking the tree was a heavy leaner or a split tree.  Since I've never seen a DF maybe I'm wrong.  No matter which way it gets sawed it will move a lot due to the tension.

I would saw nearly the same as ltp while keeping the above in mind.

[Chuck White]

Seems like you are sawing just like most of us would!

I think your only recourse would be (as mentioned) to saw them at 8" and maybe check them later and some of them may need to be trimmed to 6".

You'd lose a little lumber, but you would have good boards.

The bottom line would be for you to figure out what the boards would be used for.

Remember, those boards are called "rough lumber".

[kderby]

Looks normal compared to the fir I mill.  Trees are living and variable things even as they are turned to lumber.  I also suggest going a bit wider and re-sawing after dry.  I often put dry lumber on the mill and zip an inch off each side.  I sell a lot of board and batt.  The batts are often recovered from dry six and eight inch wide lumber that I mill down to three or four inch batts.  That give me somewhere to send the narrow lumber and the customer gets clean/uniform/straight battens.

I agree with Mr.White.  We are talking about "rough" lumber.  For the price of the logs, you can lose and inch and gain a better edge.

kderby

[Brucer]

I saw mainly D. Fir timbers and I set up the log the same way you do. The only difference is that I stop when I get to the rectangular cant -- that's what I'm selling.

I've very rarely had a slab or a flitch go sideways like that (but I see it a lot on WRC). Where I do see a lot of movement is when I saw FOHC timbers. As soon as I cut out the center the timber on top curls up at the ends. The one on the bottom pops up in the center when I release the clamp.

Usually the customer can handle the slight bow on a FOHC timber. In special cases such as long newel posts, I cut out my FOHC cants about 1/2" to 3/4" thicker then the final size. Then I saw the two curved sides straight. I hardly ever see any additional movement when resawing them.

I imagine the same principle would apply to your boards. Cut them a little wide, then resaw them to the final size while they are still on the mill.

[bandmiller2]

Lost plot,your doing everything right sometimes its just the logs nature,remember we just cut it we don't create it.If I needed straight dimension stuff I'd cut cants and set them aside for a wile to have their little hissy fits then recut.Frank C.

[CalebL]

Lost plot,your doing everything right sometimes its just the logs nature,remember we just cut it we don't create it.If I needed straight dimension stuff I'd cut cants and set them aside for a wile to have their little hissy fits then recut.Frank C.

Great response.  If the wood I use would only do what I want it to do, I would be one hell of a woodworker/sawyer.  I have built furniture from from slabs that haven't moved in years and I make one rip on them and bam, they start twisting and bending like a roller coaster. 

[west penn]

 You could also make your cant 9+ inches wide then saw your boards then turn your boards from that log "hump up" ,  trim straight then flip and cut the other side to 8 inches. A little more time but makes straight lumber and relieves most of the stress

[customsawyer]

If the log is big enough some times you can put the hump or horns at a 45 degree angle and see if that helps.

[losttheplot]

Thanks everyone, for all the great tips and encouragement.
I have only had the mill for a couple of months.
 I have made lots of mistakes.
And I think I have some of the finest looking firewood on the island  however I could not imagine trying to use the mill without resources such as this one.

The boards are going to be used for siding, on the outside of a small timber/stick framed shop I am building.Also for ship lap cladding on the inside walls and ceiling, as well as rustic flooring.




I am also sawing 1x6 along with the 1x8's. I will trim any bad 1x8's down to 6's and any wobbly 6's down to 4's to use for strapping.
I am guilty of not getting the most out of the logs that I could.
I get discouraged when I try get get an extra board and end up cutting bark.
The trees have only been down for a couple of weeks, however they are still pretty hard on the little mills bands.

I tried cutting 2x4's today but I could not think of a good way to cut a cant, with out splitting it through the heart. I think I am going to buy what I need for 2x4's from the store.

I am going to try cutting some of the remaining logs into timbers as large as I can get and then store them for a while.



Hopefully some of them will stay pretty straight.
There are twice as many again, down the bank out of sight.
Its a lot of work with just a log arch and a pick up, but its much faster than the Alaskan I have been using for the last few years.

Besides I think I have cut enough 1 by for now.



In fact I have so much my shop is full and I have not even built the walls yet !
Its hard to stop cutting once you get going..........just one more.... 



I think I have the saw dust disease.



I am not sure why all the trees are crooked here.





We have lots of hills, but the ones growing on the flatter parts are mostly crooked also.

I am trying to do the best I can with what I have, one neighbor told be they were not worth sawing, because of the off center heart.
I can only assume he does not frequent the Forestry forum 

[Brucer]

I am not sure why all the trees are crooked here.

Because they're Douglas Firs .

[losttheplot]

I am not sure why all the trees are crooked here.

Because they're Douglas Firs .

Thanks for clearing that up. 

[Ianab]

I am trying to do the best I can with what I have, one neighbor told be they were not worth sawing, because of the off center heart.

Not worth sawing is different to "not perfect for sawing". Sometimes we just have to work with what we have....

If they are moving 1/2" over the log length I wouldn't be overly concerned, and maybe cut them a bit oversize if the log allows to let you rip them straight after they dry.

For the 4X2s. As you cut the cant down, like in this picture...

Go down till you have a 4" thick cant with the heart centred. Then stand that up and cut it into 4x2s. The grain should be evenly balanced. most of the movement would be bowing towards the heart, which you can reduce by putting weight on the drying stack.

You might get a few rejects, but I bet most of them will be usable.

My mill works differently, and cuts dimensioned boards from the top down, no flipping the cant etc. You know when you have tension in a log when you are cutting a 4x2, and the free end of the board is 4" off the log as you finish the cut  But even then, get them on the bottom of the stack, weight them flat, and let them dry. Probably still come out straighter than the bought stuff..

Ian

[Larry]

It's interesting hearing you guys make fun of douglas fir.  It doesn't move near as much as our plantation grown syp.

[Magicman]

There are many ways to saw 2X4's.  Here is the method that I use.
 


Split the cant into 4's centering the pith.
 


And then stand them up and saw the 2's.

[Ianab]

But if you have tension in the log, then the 4x2s at the corners are the most likely to misbehave.

The ones in the middle vertical section should be more stable, and at least be partly controlled by the drying stack. Hence my suggestion of cutting the 1" siding, where you can balance the tension, and then the 4x2s from the final piece, again with the tension balanced.

If a board is bowing, you can usually do something, but if it's twisting, warping AND bowing all at the same time.... not so good.

Ian

[losttheplot]

There are many ways to saw 2X4's.  Here is the method that I use.
 

(Image hidden from quote, click to view.)
Split the cant into 4's centering the pith.
 

(Image hidden from quote, click to view.)
And then stand them up and saw the 2's.

That's what I would LIKE to do.

What would you do If the log was only big enough to get an 8  x 8 cant?

[Tom]

Cut 2x8's off of each side. Stand the 4x8 up and cut 2x4's from it. then stand the two 2x8's up and cut/split them into 2x4's.

It's a production (found money) kind of operation to saw in multiples like this, especially if you are alone.  But you also should keep in mind that you are sawing blind. You don't know what the boards are looking like inside of the cant.  If you cut and remove boards and flitches as you go, to be resawed later, you  might change your mind about how to saw the next board because of spike knots, rot, or other flaws.

So, knowing the techniques doesn't mean that you should make it a habit of following them every time. 

This "Reading a Log" is the important art of Sawing.  Knowing where you are going is a lot more important than knowing where you've been.

[LeeB]

When cutting off center hearts, the wood will tend to bow toward the side closest to the bark. Depending on what you want to do with the wood, a little bow is much easyer to deal with than side crook. Tom posted some picks on here once a pony time about sawing this kind of log and recovering as much as possible, least I think he did.

[Jim_Rogers]

The boards are going to be used for siding, on the outside of a small timber/stick framed shop I am building.Also for ship lap cladding on the inside walls and ceiling, as well as rustic flooring.

(Image hidden from quote, click to view.)

I hope this doesn't upset you, but whoever put that boring machine together, the last time it was apart, but it together backwards.

The sliding carriage and the gear works go on the side towards the operator and the seat.

To change it you would have to undo the four mounting bolts that hold the tower to the seat and turn it around. The straight vertical side of the tower goes towards the operator seat, so you can see any marks made on the slide while you're boring holes.

Other than that, great looking frame.....

Jim Rogers

[losttheplot]

Trust you to notice my mistake 

By the time I noticed, I was having too much fun boring holes.
It makes such a lovely sound as it turns that 2 inch bit .

I was going to change it.......... but it kept getting put off and now the mortices all done.

Could not have done the frame with out all the help from the forum

[losttheplot]

I cut some 2x4's today.

I used the methods suggested.
I made an 8x8" cant  and edged the side to make 2x8's and a 4 x 8, then split them.
The 2x8's curved towards the bark as I cut them in half.





And I made an 8 x 12" cant and sliced it through, rotating it 180 degrees a few times.
Its tough to get the heart in the center with these egg shaped logs.



All in all an enjoyable time with the mill 

Some of them moved around, over all I think they came out better than what you would get from the HD on a Sunday evening.

[Banjo picker]

There is just something nice about not having to go to the store for lumber....   Tim

[Brucer]

When I'm doing boxed-heart timbers I level the log so the physical center is parallel to the bed. When I want to saw Free of Heart Center timbers, I turn the log on the bed so the plane of the sweep is parallel to the bed. Then I level the log by setting the height of the pith equal at both tends. Finally, I draw a horizontal crayon line across the "driver's end" of the log to remind me which plane the sweep is in.

I only do this in the one plane, as the pith will be wandering back and forth in the other plane.

[losttheplot]

Would you center this one where the green cross is, cut an 8x8 out of it and expect it to stay reasonably straight?
There is no noticeable sweep to the log.
It is 12ft long.



I appreciate  everyone taking time to answer my questions.
Thanks.

[bandmiller2]

Prehaps I'am a crude old dude but folks pound their heads agenst the wall trying to get precision product from less than precision raw material.I cluster cut 2x4 like Majic the ones that really bend are cut for braces and blocking the rest put up as I best can.Part of the charm is the personality of the pieces and the fact their not perfect. Frank C.

[paul case]

what frank says plus i have not heard of too many projects that dont call for a lot of short pieces when it comes to using 2x4's. pc

[Tom]

See that Heart Check in the middle of the log?  It is Usually horizontally aligned to what would be the sweep of the log.  Many sawyers place that at a 45° angle when cutting a timber so that it reaches into the corners instead of breaking out of the sides.

When cutting boards, I keep it like you have it so that the crack/pith remains in fewer boards and the boards are all of the same "type" of wood.  The wood above and below that crack is where you find most of the reaction wood.

[paul case]

tom,
are you saying that the heart check is usually aligned with the tension in a log if any, and that should be a deciding factor in log breakdown? making it on a 45 degree would be contrary to what i usually do. i try to contain the check in as few boards as possible by placing it horizontal with the bed for the first cut and then turn 90 degrees at a time and on the last slab side saw thru and thru until it is all cut up. just my theory. i had never noticed that the heart check did or didnt align itself with tension or sweep in a log.  pc

[Tom]

I was never told this, I figured it out on my own since I saw as you do.   When putting a log on the bed to define the width of the boards, I usually would first orient the log such that the "hump" was on the entry side of the log and the saddle on the output side.  This allowed easier clamping on the Baker since it dogged the log to the entry side.  I did just the opposite with the LT40 and kept the saddle to the right.   I then usually turned it 90° to cut just get enough flat and clearance to cut the other "side slab" and begin getting my cant defined.  After that I began to work seriously on the hump and ears.

Because I was so concerned with the sweep of the log and the heart check I was paying attention to both of them at the same time.  I noticed that the Heart Check most always followed, and was horizontal with, the sweep of the log.   When I finally realized this, it made it easier to orient a to the sweep, or even the lean, by looking at the heart check, even though the log looked straight.  You can spot the heart check on the log ramp several logs ahead of sawing it even if you can't see the rest of the log.

Some logs have "Y" shaped checks and some have "+" shaped checks. That is when I pay special attention to the sweep and  growth ring patterns to orient the log.

I don't saw with the heart check at a 45° angle as a rule.  As a matter of fact, I hardly ever do.   But, there are Grade Sawyers on this forum who do, saying it is easier to keep the check in the side of the board to be able to trim it to its widest size.   Those who do this are usually cutting to a target in the center of the log that allows it to be a timber (railroad tie).  By default, this Tie will have the check running at a 45° angle which allows the tie to have more split free surfaces since the distance from corner to corner is greater than from side to side.   

Using this knowledge, one who is creating timbers can use it to their advantage to create large timbers from smaller logs.   It also allows the direction of log movement to be anticipated.   I would think that a timber cut at a 45° angle from the heart check would be more prone to twist, and one cut at 90° to the heart check would b more prone to bend in the direction of one of the flat surfaces.  Whether we think one way is better than the other would depend on its use.  Those who do timber framing would know best which would be easiest to work and may even find that one works better in one application than the other, when "straight" might not be an issue.

It's just an observance of mine that has led to an opinion.

[Jim_Rogers]

When I saw a log out that has a heart/pith check, I usually make that go from board edge to board edge. If you sawed it the other way then every board may have a split in it on that end.

I would want the defect (the pith/hearth check) all in one board or if we were lucky between two boards.

So as his log is pictured the top is a edge face, and the bottom is an edge face. Right and left are board faces.

I think this is what you're saying, Tom. But if not please educate us all.

Jim Rogers

[customsawyer]

What Tom is refering to is grade sawing of hard wood which is a different application then what is taking place in this thread. When you are grade sawing you want the check at a 45 so that you can edge each board and remove the split with the edger. When you are sawing all the same size boards out of a log then what Tom is saying applies.  IMHO
When you are grade sawing hardwood it is random width in most cases so all you have to do is keep turning the log/cant and keep the check at the edge of a board and you can trim it off with the edger and have a better grade of lumber.

[Magicman]

This is a very good discussion not only on tension but also addressing other log defects that must be contended with.

As customesawyer pointed out, it all depends upon the product that you are producing.  If you are producing lumber to sell, or if you are custom sawing for a customer.  In the latter case, you have to produce what the customer wants.

This latter case is where I saw.  As a general rule, my customers want the widest boards possible from each log.  That means that the heart check must be oriented to disappear in one or two boards as Jim previously described.
 


Oriented to open the first face.
 


Oriented to open the second face.
 


The third face has been opened.
 


Opening the fourth face.
 


The heart check disappears in two boards.
 


What the two defective boards looked like.  Remarkably, the other side of these boards were clear of defects.

The above customer wanted all 1"X12"s, and this sawing technique yielded what he wanted.

[Dodgy Loner]

Magicman's pictorial describes how I would typically saw a hardwood log with a heart check. As he pointed out, if you are sawing for maximum width (as I usually am), this is the best method to reduce the effect of the split while maximizing your wide lumber. If you are sawing for grade, on the other hand, orienting the split at 45^o is usually the way to go, because the width of the boards and the orientation of the grain are not the primary concerns.

[Brucer]

Would you center this one where the green cross is, cut an 8x8 out of it and expect it to stay reasonably straight?
There is no noticeable sweep to the log.

I don't often see a straight Douglas-Fir with the center offset that much. When I do, it is usually at the butt end only.

It's rare to have D-Fir 8x8 move very much. If I were given a log like that to saw, I would sawn an 8x10, with the 10" dimension going from left to right. If the timber remained straight I'd take an inch off each side. If it move a lot I would saw one side straight and then the opposite side.

What Tom is referring to as a "heart check" would be called "shake" in BC. It's usually caused by wind. There is no guarantee that it will remain parallel down the length of the timber. I recently sawed a 26 inch log that a customer brought in. It had some heart shake at one end similar to what you show. Nothing was visible at the other end. But the shake spiraled through the log turning 90 degrees in 16' before fading away just at the other end. Not only did it spiral, it also moved off center.

It's very common to see other cracks opening up inside the log, all associated with shake. When I see something that small, I try to keep it inside the timber, rather than sawing smaller pieces out of the log.

[customsawyer]

What we call shake down here is a crack  between two or more growth rings. It is more of a problem in Cypress and hemlock than in the hardwoods.

[beenthere]

custromsawyer
You are correct with the "shake" and Tom with the "heart check". Some people confuse it, and call heart check by the name of "wind shake". Hasn't anything to do with wind and more to do with growth stress building in the tree as it grows.

[Magicman]

Correct.  Shake follows the growth rings.  Check splits across the growth rings.
 


Shake.

[cutterboy]

Magic, I just love it when you show us pictures to make a point. It's easier for me to understand something when I can see it.  Thank you.

[Brucer]

The Canadian Softwood Lumber Grading manual identifies two kinds of shake -- "ring shake" is a split between growth rings. "radial" or "star" shake is a split across the rings. Star shake is not the same as end checking or checks caused by drying -- it occurs while the tree is growing. This is probably one of those "local terminology" things.

Several professional log buyers in BC have told me that shake in Douglas-Fir and Western Larch is mainly caused by continuous exposure to wind. I know from bitter experience that there are certain areas in this region that produce 100% wind-shook (?) D-Firs.

D-Fir and Larch are the tallest trees in the interior forests. They don't like shade and tower above the other species. This makes for very long trunks that flex a lot in the wind. I suspect that's the reason so much shake is found in windy areas.

[ljmathias]

Just an observation of the value of the forum and staying up to date- this topic has come up multiple times in different context each time.  That helps you see how one piece of information can be used in different ways: Tom's discussion of aligning the check at 45 vs 90 degrees is a good example.  My memory (such as it isvv ) had me thinking that the 45 orientation was good for sawing everything- not true and glad to have the clarification. 

The second part of the observation has to do with the combination of explanation and pictures, and part of the reason we love pictures so much here is because that's where the information becomes real.  Someone can describe something to me and I mostly understand but show me a picture or two, and wham! It's real!  Of course, you only learn how to apply the knowledge by doing- the hands-on part with all the trial and error that comes with it makes the information into application, and that's what we're all looking for.

Sorry, guess the teacher in me just won't die completely... 

Lj