Hi...I'm trying to edge joint some 7 foot boards so I can glue up a slab for a bartop i'm making for my garage. The boards are 1 1/4 thick and are douglas fir (i used 2x6s from the local lumberyard). I'm having trouble getting a straight edge, it seems the more i joint the same edge, the more concave it gets. It's very slight but it seems the jointer is taking more off the middle of the board than the ends. I'm using a Yorkcraft jointer, 6", 22" infeed table, 22 1/2" outfeed table. I haven't had this problem with smaller boards, and i'm not sure if it's my technique, or a machine setup thing.
Any advice would be appreciated... Thanks, Ken