Board Tolerance After Face Jointing

[Mike Granby]

I've just run a 4' x 6" x 4/4 walnut board over my new (and first) jointer, and I seem to be having trouble getting the board's face completely flat. There's still a very slight concavity, rising to a height of about 1/64" in the center. I'm concerned that the curve might be caused by either (a) despite trying to have a very light touch, applying too much pressure during jointing, thus flattening out the natural concavity so that the jointer can't correct it; or (b) having the knives too high relative to the outfeed table. Before I investigate these matters further, am I wasting my time trying to get rid of this amount of curvature? Is a tolerance of, say, within 0.008" a reasonable level to shoot for?

[George]

Sounds more like a pressing problem than a blade/table. Those kind make tapers or snipes.

I only guide on the infeed table, pushing down and through on the out when taking a full pass. To allow for the possibility of outfeed droop, which might produce what you have, I feed stepwise within a foot after the knives.

To clear up concavity of a minor nature, start jointing near one end (13-1/4 of length) to flatten, before running full length. In this case, hold down to reference infeed. If the concavity's bad, joint one end, then the other until it looks close, then full length.