jointer help

[martin fleming]

So apparently I am doing something wrong with my jointer as I cannot get a perfect straight edge on a long, say 4' board. I have checked and reset my jointer, a 4" grizzly parallelogram. My out feed table is exactly the height of the knives all the way across the knife width, and the tables are parallel when checked with a four ft straight edge.
BUT, i always end up with a bit of taper on my beginning edge (the board measures, say, a 16th less wide for the beginningcouple of inches than the remainder of the board). And if I swap with the other end, then both ends have the taper!
Ive been told to keep the pressure on the outfeed table. When i do this its fine for the first four inches or so and then the board sort of rocks up onto the outfeed height and theres clearance on the infeed table and i dont get any more cutting action. If i keep pressure on the infeed table the there ends up being a clearance gap at the far end of the outfeed table and that messes up the cut, of course.
Is my outfeed table set too high? When i put a straight edge on it, it just touches the knifes as i rotate the cutter head thru.
Thanks for any help.
Martin

[Andrew Hughes]

Hi Martin,It just sounds like you need to create a hollow back in the board,What I do is start a flat spot in the middle and work it out to the edges.
If your outfeed table is too low you will get snipe at the trailing end,If it's too high it get kinda hard to push the wood as it may start rubbing on the lip of the outfeed table.
The thickness or the wood can make a differace in the technique,thinner boards are tricky because they flex here and there as we push on them.Feel free to ignore me if you already know.Hope this make sense.Aj

[Mel Fulks]

Out feed table is too high,maybe just a couple of thousandths. Doesn't take much. Best way to adjust is start low and gradually raise . Joint two boards about three feet long to keep checking. Using a portion of the knives where there is a
nick can also, in effect make out feed table "too high".

[Myk Rian]

Run 4" of board, and stop there. Turn the machine off.
Put that jointed part over the cutter head so it is over the out-feed table.
Adjust the table to touch the board.

[glenn bradley]

I'm going with feed path. I don't know of a 4" parallelogram jointer from Grizzly so I'll assume you mean the 6". The total table length is about 55" so your infeed is short of 48" I would guess. If the unsupported material hanging off the back of the infeed is lower than the infeed surface it will climb the leading edge as you follow your feed path. As Andrew states, knock off most of the offending points first. This will cost you less material overall as you reach your flat, straight end result.

[Mike Gresham]

A few thoughts:

If the outfeed table is set too high, the leading edge of the board usually catches on the edge of the table. It can be a barely felt bump or full stop.

The way you describe the board rocking up when you put pressure on the outfeed side sounds like you are jointing with the crown down. I was told to joint crown up to prevent that problem. It seems to work for me.

It could be that you are putting too much pressure on the board as you feed it. It took me a while to figure out that you can actually distort the board and cause problems.

I don't know how long you have been using a jointer, but jointing 2x4's can be instructive. It is much cheaper learning on that than good hardwood. I chewed up quit a few learning. One thing for sure is that you will see every kind of cup, twist and bow that's possible.

Mike

[peter gagliardi]

Out feed table is too high,maybe just a couple of thousandths. Doesn't take much. Best way to adjust is start low and gradually raise . Joint two boards about three feet long to keep checking. Using a portion of the knives where there is a
nick can also, in effect make out feed table "too high".

Mel is right on here! You want the out feed .001-.002 BELOW the apex of the knife arc.