proper way to deal with a convex edge when jointing?


What's the proper way to deal with a hump in the edge of a board you are jointing.
One that lifts the front off, then when you transfer to the infeed side, you lift the tail off the table.
I've tried starting the board a bit over the knives, but normally resort to my hand planes anyways.
Normally I'm pretty quick with a jointer plane now and always check the edge with a starrett square to make sure. I shoot for no light, and no visiable seam.
I learned the hard way when I hand planed my son's bed that .004 was very noticeable.
Alan
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arw01 (in snipped-for-privacy@g14g2000cwa.googlegroups.com) said:
| What's the proper way to deal with a hump in the edge of a board you | are jointing.
Joint the other (parallel) edge first. Take the board to the table saw and dispose of the hump. Then go back to your jointer and take a very light cleanup pass if needed.
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/solar.html
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wrote:

If the hump is so that the piece rocks when on a flat surface, start with the piece barely on the out feed table and run to the middle of the piece. Then turn the piece around and do the same thing and run back to the cut you just made. Take a small amount at a time to avoid tear out, as one way will be against the grain. Repeat as neccessary. Once the piece is as straight as possible make a final full pass with the grain.
Mike O.
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Now wouldn't that make the hump worse, since you starting with it on the outfeed, going to the middle, stoping, and flipping, and doing the same thing again?
Would make more sense to push the far end down so the board does not touch the knives, go about 1/2 way, then flip and repeat. I would expect this to knock the hump off.
I've not tried the flip with a hump.
Alan
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wrote:

Let's makse sure we're talking about the same crooked board. If you stand it on edge on a flat surface, does the board rock or does it touch at each end? If the board rocks, the method I described will work to make it straight.
If the board is crooked the other way, then you start in the middle of the piece (or the high part of the hump) run one end. Turn the piece end for end, start again from the middle, and run the opposite end same edge.
Mike O.
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start in the middle
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I though I was the only one thinking that. LOL
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Alan, I think you've gotten good advice so far, but what they haven't mentioned is weight transfer as you move the board across the jointer knives. Start the cut with downward pressure on the trailing end of the board. This will rock the leading end up so that it doesn't touch the knife until almost the middle of the board. Then, as you slide the board across the knives, when the knives have been cutting wood for a few inches, shift the pressure to the leading end of the board so that the trailing end is lifted up. That way, you only cut the middle hump. You should find that the board contacts the cutters for more of its length with each pass. When you're cutting wood along the entire length of the board, your edge should be straight. If not, your jointer is out of adjustment or the board is too long for your jointer.
Having said all that, I find it easier to work the other edge - the concave one. Run that edge over the jointer until it's straight. Then remove the offending hump with a table saw as was mentioned in another post. Or, If the board is not too wide, turn it on edge with the good edge down and run it through your planer.
DonkeyHody "Every man is my superior in that I can learn from him." - Thomas Carlyle
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