Today I was edging poplar making 1x6 eight feet in length. I was taking 4 in off the boards. Those pieces were the Barton strips. The problem I had was on the 1x6 boards. After edging them,3 at a time. I noticed they were not straight. Both ends of the board were straight but the middle of the board was not. It was about 1/8 of an inch off from the ends appeared like a saddle in the middle of the boards. Thought maybe I was running the power feed to fast or this might be an accepted tolerance for rough cut lumber. Any advice is appreciated.
Was the poplar green off the saw? It sounds like stress in the log that translates to movement in the boards as they come off the saw.
Yup, as you saw a log, you release the stress in that log. Depending upon how you set the log up for the initial face opening will determine whether the boards will have a bow or a crown. If it is crowned and you flip it 180°, then you have all kinds of possibilities for irregular lumber.
Yes it was green. Any tips on how to avoid this and reduce the stress when sawing?
Could very well be stress but make sure you enough pressure on your center jacks. Steve
If it is stress in the log, and I have seen a good bit of stress in the upper logs in yellow poplar, then the way I deal with it is to square up the cant trying to center the pith if that is possible. Then only cut a few boards before flipping the cant to the 180 degree opposite face and doing the same. When I am approaching the pith, I always flip the cant 180 degrees instead of cutting on through. That helps reduce the stress by flipping the log so that all the stress is not telegraphed only on one side of the log. It also leaves the last board that will show the most effect of the stress (usually thick on the ends and scant (narrow) in the middle of the board) as the one with the lowest quality since it contains the juvenile wood of the pith. One sure sign of stress in the log is when the board you are cutting begins to raise up off the cant behind you as you proceed with the cut, or it starts to bend side to side.
It is kind of like if you plane a board and only plane one side down, the board will rarely stay straight.
To reduce the tenancy for boards to crown, after squaring the cant saw through from the horn or hump side. And follow WDH's suggestions above.
One thing nice about a scragg like ours is that we can saw boards off both sides at once equalizing the stress.
I know it doesn't solve your problem.
When sawing some small poplar on the WM we have someone raise the end as we saw and lower it as the saw goes down the log keeping the cant touching the mill under the saw blade. We even stop and let the lifter go to the other end and lift. A little slow, but it makes for much better lumber.
I've used that one on long logs that don't want to hit the bunks the full lenght, that's why I said to make sure the center jacks had pressure on them. With not enough pressure it will saw low in the center and thicker on the ends. Steve
Today I checked my mill after seeing some suggestions on here. I noticed my middle legs that are closest to the rear of the sawmill were not touching the ground. I think that might be my problem. I am going to finish the poplar tomorrow so I hope that was my fix. I did a mobile job last week and it looks like I failed to properly set my stands. All other stands were ok but these two. I also think the poplar had some stress in it. I remember a few of the boards popping up after I sawed them. Thanks for the help.
Popping up is generally better than popping sideways. Of course when sawing stress logs, you will see either or both. When you start releasing the stored up energy in a log, things happen. You just try to have them happen your way.
Another way you can do this is to leave the boards on the cant as you are sawing through as there weight will help to hold the cant in place. This does not always work and you will soon learn which logs you can do this on and which will require the flipping 180° method.
Initially reading the log and opening the proper face is the key to avoiding most stress related issues. No, I am certainly not a "log whisperer", but I have sawed some mighty crooked logs.
I generally saw perpendicular to the stress. Those boards that rise up in the cut usually go into a cull pile that I use for stakes and other things where straight is not required. Trying to dry reaction wood is often a waste of time and energy. some exceptions might be slabs that will not be resawn, some framing lumber, maybe some types of siding etc...just my 2 bits.