When cutting boards off of let's say a 10" wide board and we want (3) 3" wide boards will the 3 pieces come out straight if going through a gang rip saw? I straight edge board on a slider then over rip to 3-3/8", re-sraighten and then rip to
3". One board 10" wide may produce 3 straight boards right from the start but you
never know which one is going to get a bend in it. I'm thinking when multiple blades
are cutting the stresses are eliminated resulting in straight boards. Any info appreciated.
Thanks,
Al

Stress is never eliminated. Only dealt with. You will have loss.

Define straight

In my opinion they will only come out straight if the drying of the lumber was done correctly.
Were talking about two different styles of saws here, Gang rip saws are best used for high production companies who need a large volume each day.
Straight line rip saws are more widely used by smaller companies who desire straight lumber because they can control the straightness each time they make a rip, the trade off is volume.
Each type of saw has its own pro's and con's
I guess you would be the only one can decide which saw is best for your current application.

I hope that helps
Russ

I wouldn't say all stresses are due to poor drying. There are plenty of stresses which were grown in the wood while the tree was living.

Usually you can see this, by a change in color and thickness of several annual rings, usually in a more orange or yellowish dull color, as well as a fuzzing of the surface.

This can be present in a clear wide board which is straight and properly dried, but will be useless when you rip it, regardless of which method you choose to cut it.

Good Point Ken
I would agree with you
Russ

On the sawmill some "boards" stand up 6" in 8'.Pretty tough to eliminate all stress.No offence, but how good is the wood to start with?Would improving the grade be an option?Or purchase the straightness required,perhaps .

We are just small production and slider works nicely in straightening for little amount we do.
As far as drying properly I could see that but from same stack of boards some stay straight
and some do not so I think it's more on the wood itself. Sometimes you think the perfect board will stay straight and then it doesn't and vice versa the dog in the pile stays straight.
I guess I'll just stick with the way I have been doing it.

Mereen-Johnson malkes a glue line gang rip saw. 'Glue line' speaks to the quality of the cut and that it is straight enough to be glued for width right off the saw.

If lumber has stresses that are going to cause it to move after straightlining, it doesn't know or care what type of saw is used.

Both lumber and saw need to be up to the task.

I agree with all of the posts. We are a small shop and got a SL saw 8 or 10 years ago. Been very good. SL an edge, rip a pc. If remaining pc. takes a curve, SL that edge again. Much faster than using a slider and you can SL longer boards. Slight variations will creep in as the boards get longer but the cut quality is still good enough for glue-up. Your slider is probably limited to 10'. The SL saw by how bright your laser is. Buy an after market laser. Our saw is a 12", 15hp Extrema, 4 & 5/4 run fine @ 99'/min. 8/4 needs to be run slower as you run out of hp.

Here is what I used to make straight blanks to run through my moulder. The sawmill I bought lumber from would have several 16" - 18" boards in every batch. One pass through straightlined and cut the blanks.

http://www.woodweb.com/galleries/shop/posts/593.html