Crooked RIPs

[Jeff Cord]

I'm having an odd problem that I'm curious if anyone else has experienced.
I'm making some rails and stiles out of poplar.
I have checked the rip fence and it is straight and it is properly adjusted so I don't believe it is a problem with the equipment.
The wood has been sitting in the garage for a few weeks so it has had time to acclimate.
I have jointed one face and one edge, then I planed the second face so I'm confident that I have one very straight edge on the wood.
When I rip the a piece of wood (it's about 6" wide to start with) the first time I see the edge of the wood very tight against the rip fence.
I then rip that piece of wood for a second time (it's now a bit under 4" with the cut edge from the first cut against the rip fence) and I notice a gap between the edge and the fence.
Is this normal? I was expecting the see the wood on the second cut tight against the rip fence as it was during the first cut.
Thanks in advance.
Jeff

[Greg Funk]

Jeff,

This is not uncommon. Wood will often have internal stresses that are relieved when you rip into narrower strips. It wouldn't hurt to run the board through the jointer after each rip.

Greg

[Jesse Thornton]

If there is a consistent gap, perhaps your blade is slightly out of square witht the table, making it so the bottom edge of your rip is tight against the fence but the top edge is slightly off? If there's only a gap in some places (ie the egde isn't straight anymore) perhaps there is some tension in the boards that is being released after the first rip - it's not that uncommon even after acclimatizing for a bit. Or maybe your blade has a bit of wobble to it?
Edit: Just noticed that Greg said the same thing about tension in the wood as I was writing this post. I had the window open for a while while I was multitasking.

[Jim Becker]

As stated, it's probably tension in the particular wood you have being released. The "fix", as it were, is to rip slightly oversize and use the jointer to straighten the edge and bring to final thickness. Setting your jointer to 1/32" lets you do that with relatively good accuracy. (That's about where I leave mine "permanently"...)

[glenn bradley]

Greg has it. You will see this on some boards and not on others depending on stress factors. The re-jointing is an additional step but it is the cure for what you describe.

[Mark Carlson]

Jeff,

Check the 1st board you cut and you'll probably find that the original straight edge is now no longer straight because of the internal stresses being released. I'm no expert but I can think of two solutions to this problem. Rip over sized by 1/4 inch or so, rejoint 1 edge and then make a very slight rip to straighten the other edge. This last rip will just take a sliver off which wont release internal stresses like the 1st rip. The 2nd solution is to rip oversized, joint one edge and then run the boards thru the planer to final width. You will need to run the boards thru the planer on edge so you'll need to do a bunch at the same time.

~mark