Spruce logs, growth rings not concentric.

[deeker]

I don't know how to cut and get the least warp from these former leaners.

Going into 2 1/2" x 12" boards for picnic tables.

Pics of the end grain sunday....

Ideas????

Kevin

 

[Brmorgan]

Is the log crooked in addition to having an offset pith? If so, the best way to mill is curve sawing, and THIS PDF may be of interest to you. However curve sawing isn't so practical outside of a big commercial mill. So...

If you're going for absolute stability in a 2X12, and aren't as concerned with yield, the best way is to saw parallel to the curve - for example, if you were to lay a banana flat on a table, the cuts would be made parallel to the table, so that every piece shares the same curved shape. This way the natural stresses in the wood are placed across the wide axis of the board, which is more able to resist movement. This is especially true of the boards sawn near the center of the log, since they would be more or less completely vertical-grain pieces. However, this method of sawing substantially limits either the maximum width or length of the pieces, or both depending on the severity of the curve.

If you were to cut the pieces perpendicular to the curve - if you took the banana, sat it up on the table so the ends were up, and cut parallel to the table again - you would end up with an area at or near each end of the boards where the grain deflects through the narrow axis of the piece at rather steep angles, both greatly reducing its strength and also creating a great deal of tension that will want to warp the board. This method will allow more wide pieces, but generally shorter.

If the log isn't really crooked but has a lot of compression wood, I can't really suggest much. I've seen boards with a lot of compression wood warp so badly in the kiln that the ends almost touch each other. Quartersawing is probably the most you can do to help with it.

Just a graderman's opinions, so take it with a grain of salt. I'd love to hear if the pro sawyers have any other thoughts. If you could rig up some sort of leading roller to follow the top of a curved log and let the carriage height match the log's, you could in theory curve-saw it quite well with a smaller bandmill.

 

[Mike Van]

Or, sometimes you're better off to just find better logs. Back when I got into sawing, close to 20 years ago, I thought everything was a sawlog. After much dissapointment, and a lot of 1 & 2 inch thick firewood, you learn from mistakes.

 

[oldsaw]

Or, sometimes you're better off to just find better logs. Back when I got into sawing, close to 20 years ago, I thought everything was a sawlog. After much dissapointment, and a lot of 1 & 2 inch thick firewood, you learn from mistakes.

Some call that "learning curve". I've got some walnut that is a bit unstable. Okay for short pieces though. Yep, firewood tree.

Mark

 

[deeker]

Is the log crooked in addition to having an offset pith? If so, the best way to mill is curve sawing, and THIS PDF may be of interest to you. However curve sawing isn't so practical outside of a big commercial mill. So...

If you're going for absolute stability in a 2X12, and aren't as concerned with yield, the best way is to saw parallel to the curve - for example, if you were to lay a banana flat on a table, the cuts would be made parallel to the table, so that every piece shares the same curved shape. This way the natural stresses in the wood are placed across the wide axis of the board, which is more able to resist movement. This is especially true of the boards sawn near the center of the log, since they would be more or less completely vertical-grain pieces. However, this method of sawing substantially limits either the maximum width or length of the pieces, or both depending on the severity of the curve.

If you were to cut the pieces perpendicular to the curve - if you took the banana, sat it up on the table so the ends were up, and cut parallel to the table again - you would end up with an area at or near each end of the boards where the grain deflects through the narrow axis of the piece at rather steep angles, both greatly reducing its strength and also creating a great deal of tension that will want to warp the board. This method will allow more wide pieces, but generally shorter.

If the log isn't really crooked but has a lot of compression wood, I can't really suggest much. I've seen boards with a lot of compression wood warp so badly in the kiln that the ends almost touch each other. Quartersawing is probably the most you can do to help with it.

Just a graderman's opinions, so take it with a grain of salt. I'd love to hear if the pro sawyers have any other thoughts. If you could rig up some sort of leading roller to follow the top of a curved log and let the carriage height match the log's, you could in theory curve-saw it quite well with a smaller bandmill.

Compression wood has always been a nightmare for me.
And these logs are pure compression. Straight....and compressed.
I want to avoid the firewood pile with them.

As far a "grader-man's" opinion......it is extremely insightful. And appreciated.

I have done a lot of curve sawing, and it looks great. When the table and benches match.

The customer is insistent that these logs will produce good lumber. I am certain they are fire wood. We will soon see.

Higher quality logs, such as walnut, pecan, apricot....on and on...can be used when they are crooked. But only after they are in smaller pieces and resawn. Usually for display cases.

Thanks for the information.

Kevin

 

[Coalsmoke]

Deeker, saw them slightly oversize depending on the length of slab you're dealing with and then once they have been sawed into their rough dimension and have sprung, resaw them into their final dimension. More compression will require more oversize on the first sawing. Douglas Fir is bad for this as well. This is the only way I know of to deal with compression and tension wood without turning the whole log into firewood.

 

[deeker]

Here is the log before the first cut, and after four cuts to make a square cant.

Which way should I cut through the growth rings to oversize, then resaw to 2 1/2"x 12"? Cut log as shown in bottom pic??? Or rotate 90 or???

The compression is on the right of the cant. Which is the best way to saw it?

 

[deeker]

Notice the weeds in my mill?? It is at the bottom of a hayfield. Utah is very dry this time of year....irrigation overrun.

Some pics of the above log, cutting and squaring it....part to document for the owner and questions for you guys.

Looks more like I am trying for grade...but I am not..

 

[Coalsmoke]

Well, I imagine there are more experienced and better educated people at this than me, but I'll offer my 2 cents. The compression wood is actually to the left of the cant, and is noted by the larger asymmetric growth rings. It is not the wood in the annual rings that 'looks' physically compressed. I would rotate the cant 90 degrees clockwise so the compression wood is facing up and take boards off from there. This of course is a bit of a crapshoot, but if I were sawing that, that's how I'd do it. How long is that log, 7' - 8'? If so, I'd oversize about 3/4". My theory is to try and find the most consistent section of the compression wood and saw from that.

 

[Coalsmoke]

Is the section of compression wood large enough that you would be able to quarter saw it like brad suggested? If so that would be more ideal than slabbing, but I assumed that the log would not be large enough for this.

 

[redprospector]

I've never had any luck sawing log's with compression, I keep trying, but no luck yet.
A while back I was cutting some 2x8x16's, I had a couple of log's with quite a bit of compression. One of them about crawled off the mill while it was being cut, the other I managed to get some pretty decent boards out of (it seemed). I sticker stacked them with the rest of the lumber, and banded the unit with 3 band's. Later when I cut the band's the boards with compression crawled out of the bundle, and walked off.
Those boards were a lot of wasted time, effort, and space. That's usually my experience.

Andy

 

[Brmorgan]

Back in the spring when I milled all that short 1" cedar for my friend, there were a couple pieces like that. It actually worked out quite well because I was able to get some much wider quartersawn pieces for him, and between the wood being cedar and the pieces being so short he says he hasn't had any problem with warping yet.