Hello Ted,
I can almost guarantee that you are experiencing excessive heat build up - the blade starts out cool (your first few feet are fine) and then as the blade gets hot it begins to warp and walks all over the place. The thin kerf blades are notorious for this. I speak from experience - I had once purchased an extra-thin kerf Matsushita blade that I put in a skill saw (I don't remember what it was that I was cutting) and as I was in a hurry, proceeded to quickly push the saw through the lumber. All of a sudden the thing was all over the place - I could not cut a straight line. Well, I pulled the blade out of the piece I was cutting, turned the saw on again, and watched as the very expensive (now worthless) Matsushita danced the jitterbug. The blade was warped for good and had to be tossed.
Many times an overheated blade will straighten as it cools (the Matsushita didn't) and can be successfully used again. Test this theory by making another rip (use some scrap)- when it starts to meander immediately pull the lumber off the blade and watch to see if it is wobbling. It may even straighten out as it cools. Let us know what you find as I would be interested to see if this is the problem.
Joe Greenley
Redfish Kayaks

: I had this problem ripping strips from a 17' board. 4 strips ripped fine and
: then this. I had the same problem torwards the end of a 9' board, but was
: able to cut the problem part off. The question is, whats causing this?
: There are no visible defects in the board, there are many a feather board
: being used as well as some blocks (not the ones in the picture, they're
: just there to keep the strip standing for the pic) to keep the board
: against the fence. When I saw it start, I continued to slowly feed the
: board while checking to make sure the board was flat on the table and
: fence (which it was). Im using a Freud Diablo thin kerf (.050) 7.5"
: blade. Best I can figure is that the thin blade is being pulled by grain?
: Any thoughts? Thanks in advance. -Ted

: BTW I've got 4 strips up on either side of my Guillemot (stapleless) and its
: looking like Im makin me a boat *yeehaa* (providing Isabel doesn't nail
: Annapolis)