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Planning your last cut first story

Started by Jim_Rogers, February 06, 2009, 05:11:38 PM

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Jim_Rogers

a-Planning your last cut first story

Ok, so as I mentioned, in the grading timbers thread, that you have to plan your "last cut" first.

What I mean by this is that you have to know on one face where the last cut will be so that you don't cut too deep and make your timbers wrong.

To make a boxed heart timber the center of the tree, the pith or as we call it up here in New England, the heart of the tree, should be in the center of the timber on both ends.
This makes your timber the strongest it can be and it is required of all timbers that are 5" x 5" or larger.

Here is a picture of what I mean:



In the above picture you see the box of what I want for a timber to be drawn on the end of the log on the sawmill. Let's say in this log we want to make an 8x8 timber.
So for the heart/pith of the log to be in the center of the timber the last cut on the first face has to be 4" off the heart. Or 4" above the heart.

The first face is the face with the arrow pointing to it. I always use a red lumber crayon to mark the ends of my logs so that I can see where the center is and I use this to plan my cuts.

Next we have to figure out how high this last cut will be so we don't cut into the log too deep.

The first thing I do after I have marked the first end of the log; is mark the other end the same way.
And this mark shown above, is on the narrow end of the log. And I always load my sawmill with the narrow end of the log toward the saw blade so that I can plan my cuts from there.
It is easier to do. I use a Woodmizer so the narrow end of the log, the end toward the top of the tree, is always loaded onto the log bunks with that end toward the trailer hitch end of the mill.


Now the other end is usually bigger, but sometimes it's about the same size depending on the log.

With both ends marked, I now "level the log".

To level the log I use the taper controls on the sawmill to raise up one end or the other to make each end the same number of inches off the sawmill table or bed rails.

To measure the log and figure out how much one end has to be raised, and I use a framing square and a small block off wood.

Like this:



The width of the small block of wood is the difference between the top of the bed rails that the log rests on and the top of the rail the saw head travels along.

This measurement tells me how far the center of the log is above the bed rails.

Let's say this measurement reads 6 1/4". The next thing I do is measure the other end of the log.

As shown here:



Let's say this measurement is 8 1/4" above the bed rails.

So that means the log isn't level by 2". The narrow end has to be raised.

After raising up the narrow end of the log using the taper controls on the sawmill, I recheck each end to insure that both ends are the same height above the bed rails.

Next, my ruler on my sawmill measures to the bed rails. So if the center of my log, which will become the center of my timber is 8 1/4" above the bed rails and the timber will be an 8x8 we would add 4" (8"/2 = 4"). So now the height above the bed rails for my "last cut" is now 12 1/4".

I can't cut into the log any deeper or the heart/pith will be off-center in my timber.

So, now that I know what height my "last cut" is I set my 4/4 board scale ruler, which is the sliding scale ruler on my sawmill, to the fixed ruler scale so that a 4/4 board mark lines up with 12 1/4".

Similar to this photo:



Now that I have this scale set, I can begin cutting 4/4 boards off my log and I know where my "last cut" will be.

If during this cutting of boards, while working my way to the "last cut" I see that there is stress in the log, by the log shifting or the board moving, then I may stop. And not cut the last one or two boards off this face.

I would then rotate the log 90° and saw that face:



With the log in this position I would again "level the log". Using the same method mentioned above.

And again figure my "last cut" first.

Readjust my sliding scale based on the new face measurement above the bed rails, and saw some boards of this face.

And as before if I see that there is stress in the log, I'd stop sawing this face and leave at least one board on it, and not cut too deep.

After cutting face two, I'd rotate the log to face three.

With the taper controls lowered down, I'd set my sliding scale to 8" to make the finished timber 8" tall.

But I would not cut to 8" as I have left one or two boards on face #1.

To remember what I have left on side one, I sometimes mark the end of the log with my lumber crayon. I mark a one or a two on the end of the log so that I know how many boards I have left on that face.

Let's say on face one I have left one board. On face three my "last cut" would be 8" plus one board (and the saw cut). So the Woodmizer cuts a 1/8" saw kerf, so the last cut measurement would be 9 1/8".

If I still see stress in the log cutting face 3, I may leave one board on that face as well. But usually it has been released and you can cut to the finished face.

After finishing face 3, I'd roll to face #4 and do that in a similar method.

When face 4 is done, I'd roll back to face 1 and take off that last board. And then do the same thing to face 2.

This method has worked for me for many years to create timbers with the center of the log in the center of the timber on both ends.






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

Jim_Rogers

Next we'll look at grade once the beam is done....

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

WILDSAWMILL

Kascosaw2B

Raphael

I tend to cut opposite sides and remove all four slabs first to get them parallel to the center of the log.  I suspect this is mainly a difference in technology as my scales and blade are fixed and the cant is raised on independantly controlled log beds.  Otherwise the process is basically the same in that I plan for that last cut as I remove the slabs.
... he was middle aged,
and the truth hit him like a man with no parachute.
--Godley & Creme

Stihl 066, MS 362 C-M & 24+ feet of Logosol M7 mill

Jasperfield

Jim,

That is a good post. Keep 'em comin'.

swampfox

here, here.  Thanks Jim.  your explanations are much appreciated. 

Jim_Rogers

When inspecting a finished timber you have to look to see if the heart/pith of the tree wandered out of line from one end to the other.
Sometimes the heart/pith will show exactly in the middle of both ends but along it's length the heart/pith has wandered so far that it has actually left the piece and then dives back in further down the piece.

This is called grain run out.

As shown here, the heart/pith is at the red arrow:



When you see this here. You can see that during the time it dried the grain actually separated at the annual rings and have opened up quite a bit.

You might say, so what's the big deal about this......?

Here is the same piece looking at it from the end:



The piece is only a 4x4 and the grain ran out the side and when it dried the piece really took off and distorted something awful.

And looking at it closely, I see that the heart was way off center in the end closest to the camera. This also shows why it is important to have the heart/pith in the center.

In bigger timbers it may not distort as much, but if it can, then most likely it will..

Sometimes it doesn't take much sweep, bend or bow, in a log to make the heart/pitch run out the side of a timber.

This is why you really need to pick the straightest log you can find to mill into timbers.

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

moonhill

Jim, your last two pictures reach the far ends of the spectrum.  A beautiful stick of pine and a square stick of fire wood.  I  am looking forward the the grading section.   

Tim

As a off topic side note I see there is a new message center at the top of the page.
This is a test, please stand by...

ljmathias

Thanks for the information on cutting, Jim- as always, clear, concise and complete.

One observation and question: your stacks of lumber are not all the same size as others have indicated on the forum is important.  I find myself cutting whatever the log seems to offer tempered by what I think I might need in a the next year or so, which means I usually end up with a mix of lumber sizes from 1Xwidest to 2X dimension to some bigger sticks for timber framing.  Problem is that I don't have that many stacks I'm building at one time for each size I cut so I do a layer-by-layer stack with thinner stuff intermingled with thicker.  You seen any advantages or disadvantages with doing it your way?

Thanks-

Lj
LT40, Long tractor with FEL and backhoe, lots of TF tools, beautiful wife of 50 years plus 4 kids, 5 grandsons AND TWO GRANDDAUGHTERS all healthy plus too many ideas and plans and not enough time and energy

Raphael

I tend to stack by length and species (or type) rather than thickness, the dissadvantage is the thickness you want to use next is always halfway down in the stack and/or the longest boards are always at the bottom.  (Murphy's law) ::)
... he was middle aged,
and the truth hit him like a man with no parachute.
--Godley & Creme

Stihl 066, MS 362 C-M & 24+ feet of Logosol M7 mill

Tom

ljmathias
It would be the best for a stack to be all the same for air drying, but it isn't always possible or economical.  The important thing is that the board that are on the same level are the same thicknesses.

Those who stack different thicknesses on the same level will spend an inordinate amount of time shimming the stack to try and get the same weight distribution on one board as the other.

The same goes for lengths.  If you are stacking short boards and then put some longer boards into the stack, the ends of the longer boards aren't supported. It is difficult to shim something like that.  If you mix lengths, put the longest on the bottom and make sure that your stickers are aligned and supported such that the weight goes to the ground or whatever you are using that simulates the ground.

In the photo above where Jim is showing runout, the separated growth rings are called shelling.



When laying a floor or deck, shelling is important.  shelling generally occurrs on the pith side of a board.  That is one of the reasons that most decking and flooring people will lay a floor with the pith side down.  It minimizes shelling.  Shelling is dangerous in walking surfaces.


moonhill

Sticker placement is important as well.  With the sticker 12"-20" in form the end of the board you will recieve a check all the way into the sticker location.  Place your stickers as close to the end as possible and on top of each other.   One more reason to have ther board pile the same lengths.  But we don't live in a perfect world and my lumber yard is a disaster, it is mustly culled stock anyway. 

Jim, what makes up a grade 2 or better timber?

Tim
This is a test, please stand by...

Jim_Rogers

Quote from: ljmathias on February 08, 2009, 07:19:10 AM
One observation and question: your stacks of lumber are not all the same size as others have indicated on the forum is important...........
You seen any advantages or disadvantages with doing it your way?

The stacks in the background of these pictures with the 4x4 were for a customer who was about to erect a pole barn for his tree service business. He was making a 40'x50' building with at least a 16' ceiling in the truck bays.
I was cutting 2x6 planks for nailers and 1x10 boards for siding. Anything else was random width and placed into it's own pile for him to sort out later at his location.

As mentioned, you really need to make each layer the same thickness. This above all is most important. Set thinner stuff aside until you have a full layer of that thickness, if you are going to mix thickness layers into one pile.

If you have a set of forks for your tractor to pick up lifts then you should establish a set of standards that you will follow for your yard.

What I mean by this is to set some block on the ground next to your mill and make them say 8' on center. I do this and add one in the middle. This gives me three bearing points to rest my lumber on. This is if it's not going to be on hand for a long time.
Then as I generate piles of lumber and I have to move them off away from the mill, I put out blocks at the same widths and then stack these piles off away from the mill, and I may sort them out later on. Doing this means that each pile made near the mill has the same sticker spacing and same block spacing and when you move them off you can stack bundles up and the bearing will be all the same to the ground.

Here is a picture of what not to do:



As you can see in the above photo the blocks aren't all aligned vertically. And the combined weight is bearing down and bending the boards of the lift in the middle.

This is not good, and this pile was re-stacked and improved so that the lumber wasn't bent and wasted.

I know that it is impossible for small operators to have a single pile for each width and length of type of lumber. It was for me.

So what I did was to make one pile for each length of lumber and separate each width in layers in that pile.

I did this by creating large lumber pallets for my fork lift to carry.

Each pallet is the length of the lumber being stored on it. And each layer is a different thickness.

Here is a drawing of a lumber pallet:



How I made this is that the bottom pieces are 2x4's 4' long turned up on edge, and spaced 2' on center. Then there is 5 1x4 pine boards then a sticker over them the sticker is kiln dried oak and it is 1x 1 1/2" x 4' all assembled with a nail gun.

This drawing is of an 8' lift.

Now here is a shot of my 12' pile:



As you can see in the above picture there are several layers in the stack. These are all 1x pine boards of different widths. As labeled.

The bottom most stack, not labeled, appears to be some older 1x6 I have on hand.

The next stack up the widest I usually stock is 1x12 and I stack them three to a layer so that there is plenty of space between them for air drying.

The next stack up is 1x10 and I stack them four to a layer so that there is plenty of space between them for air drying.

The next stack up is 1x8 and I stack them five to a layer so that there is plenty of space between them for air drying.

The next stack up is empty but that is for 1x6 and I'd stack them 7 to a layer so that there is plenty of space between them for air drying.

The last or top stack, with the current level of snow on it is 1x4's and I stack them 10 or 11 to a layer so that there is plenty of space between them for air drying.

I usually never or hardly ever sell any 1x4 so I use these to make my pallets from.

In the stack behind the 12' stack is the 14' stack and there are many layers in that pile.

Doing this stacking in layers, means that only one footprint in my yard is 8', 10', 12', 14' and 16'.

Then when someone drives in and says: "I want to buy some 1x8x12 do you have any?"

I can easily walk out into the yard, with them, look at the stack see the 1x8 layer, see how many boards I have by doing the math of # of boards per layer x the number of layers and give them an answer.

Then when they say ok and we begin to sell them, I get the fork lift and set the 1x4 layer and 1x6 layer aside and hold the 1x8 layer on the forks and slide the lumber of the pallet onto their truck and make the sale.
After they leave I re-stack the layers and all the lumber is being held flat and level.

Most stacks don't have any covers over them as I haven't made that many and the top layer is always 1x4's and if they go bad I really don't care as I rarely sell them and only use them for making more pallets.

This system has worked for me for many years.

Hope this has helped you.

Jim Rogers

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

Jim_Rogers

Quote from: moonhill on February 09, 2009, 07:01:44 AM
Jim, what makes up a grade 2 or better timber?

Well, that question, seems simple enough but it has a very complex answer.

The first thing you have to understand when you get your grade rule book, and open it to chapter 6 and see the title, which is "Timbers- Beams and stringers, Posts and Timbers" is that there are two sections or classifications to timbers.

One is Beams and stringers.

The other is Posts and Timbers.

Now, if you look at the glossary you'll see that a beam mean it is a horizontal timber.

And if stringer is in there, it should/would say it's the piece used to hold up stairs.

We all know that Posts are vertical timbers.

But we you need to understand is how they separate them.

In the NDS books there is a definition, somewhere, that tells us that when a timber is more than 2" deeper in height then the width it is classified a Beam and Stringer.

So, for example, a 8x8 could be a post, it could also be a tie beam. It gets it's name from it's location in the frame.

An 8x8 is in the Posts and Timbers section as the dimensions are within the 2" rule.

A 8x10 is also in the Posts and Timbers section.

But as soon as the section dimension, the height, is more than 2" it moves the timber to the Beams and Stringers section.

Then, a 8x 10 1/2" would be in the Beams and Stringers section.

The reason for this is that the grade rule agency figures that if the timber is deeper and 2" it will most likely be used as a beam. Therefore it has to meet Beams and Stringers rules.

And the grade rules for these two sections are a little bit different.

I hope you would understand that a timber in the Beams and Stringers section has to be stronger because of it's intended use.

Timbers used as posts are not under the same load stress as beams maybe under.

So timbers used as posts have less strict rules.

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

moonhill

Jim, how about knot size, slope of grain run out and other defects which would effect the #2 grade standards? 

Tim
This is a test, please stand by...

Stephen1

Jim, very nice description. I like the way your wood is stacked. a few more readings and I believe I will be able to do that here.
IDRY Vacum Kiln, LT40HDWide, BMS250 sharpener/setter 742b Bobcat, TCM forklift, Sthil 026,038, 461. 1952 TEA Fergusan Tractor

Jim_Rogers

Tim:
In regard to knot sizes, the rule book used to have a percent of face rule.
So that when you have a face of a certain width the knot size could only be a small percentage of that face.

Then they updated the rules a while back and now the rule book has actual knot diameters listed per the width of the face.

And these are different for each section, Beams and Stringers, and Posts and Timbers.

All of this starts at timbers that are 5" x 5" or larger. For smaller timbers they are in another section and are considered planks. A 4x7 maybe considered a plank.

And if it is then it will fall under the plank rules. Including knot sizes for planks.

As mentioned this gets very complex very fast.

I don't have any pictures on hand in my computer of fresh sawn pine timbers, and I'm not cutting any pine right now.

I'm cutting some white oak strips for a boat builder.

When I have some pine timbers to photograph, I'll take some photos of knots.

In the mean time if anyone is interested in purchasing a NELMA grade rule book so that they can start their own study of grade rules, here is the webpage address: www.nelma.org

And here is the page where you can see the book, it's only $8:
http://www.nelma.org/Page-13.html

I'm not sure but you maybe able to view it online as well.

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

Jim_Rogers

I know how much you guys like photos.

Here is a short of a stack of 8' lumber:



And here is a shot of a larger pile of lumber for a project I did:



Due to the fact that my forks can only lift 1000 lbs of lumber I have to keep track of my lifts and make sure I don't hand stack a pile larger than that.

That's why you see so many small lifts.

Here is one of my favorites:



It is titled "lumber leaving the yard".....

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

Piston

I was just rereading this post from a long time ago, and figured I would "bump" it to the top.  I refer back to this post (among many others) from time to time and think it's very helpful and informative. 

....although, I'm surprised it's not under the "sawmilling" section of the forum?
-Matt
"What the Lion is to the Cat the Mastiff is to the Dog, the noblest of the family; he stands alone, and all others sink before him. His courage does not exceed his temper and generosity, and in attachment he equals the kindest of his race."

beenthere

The subject title is misleading, as the mispelled word throws one off.
The base word is "plan" not "plane", as in 'removing wood'.

Should read "Planning".  Will need an admin to correct it if it is of any importance, which it may not be. ;)
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Jim_Rogers

Quote from: beenthere on July 14, 2012, 10:37:36 AM
The subject title is misleading, as the mispelled word throws one off.
The base word is "plan" not "plane", as in 'removing wood'.

Should read "Planning".  Will need an admin to correct it if it is of any importance, which it may not be. ;)

Title corrected thanks for the pointer. Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Chilterns

Hi Jim,

This is an excellent topic and Piston is quite correct to bump this one back up to the top of the pile again.

Here is the challenge !

How do you support and saw a curved tree to produce a book matched pair of cruck blades or feature curved braces ?

What effect will the release of internal stresses in the log have on the flatness of the sawn face ? Does this matter ?

Chilterns

Jim_Rogers

Yesterday, my logger came in with some logs. In the junk pile he placed two curved logs. One is small and I may pull it out to make a pair of curved braces. One is longer and bigger that may make a good cruck log.

Recently I had a timber framer from Cape Cod contact me that he may need some cruck blades. So I'm going to pull this log out and saw it up.

I'll take step by step pictures when I do them.

In the past, I cut these:



What you do is place the log on your mill with the end towards the hitch or operator in a position so that the blade will enter the log.

The log has to be fairly level. Both ends and the middle have to be off the table the same amount. When I say ends I mean both end pith distances have to be the same off the table. So you may need to shim up the small end with a board or two in order to get it right. Then you shim the bend in the middle a little as well so that the pith is level.

You may need to put a board up as a fence along your log rests, as well. This board may get cut so don't use a really good board, something you don't care about and will be thrown away afterwards.

Next, you don't "hard" clamp the log. You just start sawing it as it sits.
You are going to cut on the top surface of the log, just enough to give you a nice opening face all the way down the log. You may even cut a little deeper if you need to.
But it all depends on how easy the log will pivot.

As you cut down through the log you'll get to a point where you can't continue because the outer blade guide are going to hit the log due to the bend. Stop sawing. Stop the blade from moving. Leave it in the log, and use your peavy and pivot the log around until the blade guide will clear the part it wouldn't clear before.
Once the log is clear finish sawing it all the way to the end.

You may need to plan your last cut first in order to get your finish pieces to be the correct thickness for your brace stock or whatever you're using it for.

I believe in the above examples these were 4" thick. So I planned on having the log cut to be 8 1/8" thick. Or maybe I planned on having two 4 1/8" thick pieces of brace stock. So the finished cut on the second side of my log would have been 8 3/8" off the table. So I'd have 1/8" for the saw cut to separate them.

After you have one side cut flat you flip the log over and make the second cut doing the same thing. But now it's much easier as you have the flat sawn surface against your log table rails. And the log will pivot much easier.

I have done this without stopping the saw. We just set it going forward real slow and pivoted the log with a peavy as it was being cut. You'll have to make sure you can completely pivot it before you start. If the log catches on the rail dogs you may have a problem. You can set the log on some boards to lift it up above the rail dogs so that it can pivot out enough. If this is so, then you'll have to add the board thicknesses to your scale so that you end up with the right thicknesses of the finish pieces.
You need to plan it out carefully, and write it all down on paper so you don't forget to add it all up to come out right.

Once you have both sides cut flat, you cut it once done the middle separating the two halves.

If you plan it right you can do it all with just three cuts. But that all depends on the size of the logs and your finish thicknesses.

As I said I'll take pictures next time when I do it.

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

Jim_Rogers

Quote from: Chilterns on July 15, 2012, 02:49:31 AM

What effect will the release of internal stresses in the log have on the flatness of the sawn face ? Does this matter ?


We didn't find any stress that I can remember in these two eastern white pine pieces.

I have done the same thing with curved cherry branches and curved cherry logs, but I don't remember any huge stress in them either.

I don't think it matters, much.

When the timber framer gets these pieces if they have distorted some he'll just plane one side or both sides flat.

Here is a picture of one of them in place in the frame:





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

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