Help with jointer technique

[Jared Cuneo]

It seems that I'm having a hard time removing bows in boards. The jointer is tuned and produces good joints most of the time that are nice and square with very little if any snipe. However every few boards with a nice bow in them will not cooperate.

I've been easing the leading edge into the knives and using very little pressure, and shifting to the outfeed as soon as possible. The issue I think is that its harder to move the warped boards forward and I think I wind up putting too much pressure on the outfeed, essentially flattening the board, so I wind up with a somewhat flatter (and thinner :) ) springboard :)

Any thoughts?

JC

[Wilbur Pan]

That is almost certainly what is going on with your boards.

If you have hand planes, I've found it very useful to scout out the high points on a board with a straightedge or winding sticks and knocking them down with a hand plane before going to the jointer.

The other thing to try is using more forward pressure and less downward pressure while jointing.

[Dennis Peacock]

This will be an interesting thread. :)

But...looks like Wilbur has you well on your way to a solution.
And do, you do not want much downward pressure, especially when dealing with bowed boards.

It would be great if everyone could post a jointer technique...just to list them all. Then the list would be searchable. ;)

[Wilbur Pan]

Actually, the only reason I can speak to a solution to this problem with such confidence is that I have turned many bowed boards into really thin bowed boards on a jointer before I figured out how I was screwing up. :o

But overall, I haven't hit a jointer problem yet that couldn't be addressed by using a hand plane and selectively planing first. This will take care of twists, cups, winding, and any other variant of bending a board may throw at you.

Of course, if I was better at selecting stock in the first place, I wouldn't have these issues, either. ;)

[Don Lehman]

Simple things first:

really sharp knives (reduce the need for feed/downward pressure)
jointer tables smooth and waxed (reduce the need for feed/downward pressure)For advanced jointer operators:

Are you familiar with the technique for tapering on a jointer?
To make a taper cut, you take the leading end of the stock to be jointed, place it carefully on the outfeed table - just an inch or so past the cutterhead - with the jointer running. You then push the stock through normally - since depth of cut at the leading end is 0" and the depth of cut at the trailing end is 1/32" or whatever you have dialed in, you have just slightly tapered your workpiece.

This same technique can be adapted to remove bow from the face of a workpiece. Position the workpiece so that the midpoint is over the cutterhead, then feed the stock through normally. Reverse ends, repeat as necessary.

After you have gotten most of the bow out, then make a normal (non-tapered) cut.

Please Note: This is a technique used by professionals and assumes that you have a properly working jointer, properly guarded, and you know how to operate it correctly.

Please Note: Stock should be positioned for a taper cut while the jointer is running. If you try to place the stock with the jointer off, then turn it on with the workpiece already in place, you greatly increase the risk of kickback. DAHMIKT

[Greg Crawford]

The Joyblock from Woodworkers supply has a retractable heal, plus is very sticky. This means it takes less downward pressure to get a grip on the board, and can even hook over the end for less pressure. I love mine, and use it on the router table and table saw, as well.

[Greg Funk]

The issue I think is that its harder to move the warped boards forward and I think I wind up putting too much pressure on the outfeed, essentially flattening the board, so I wind up with a somewhat flatter (and thinner :) ) springboard :)

Any thoughts?

JC
Like Don said above make sure your jointer knives are sharp. If the knives are dull you will have to apply too much pressure in order to feed the board through the knives. One simple test is to try taking a lighter cut. This will lower the pressure you need to use.

Greg

[Jared Cuneo]

great suggestions, will try!

JC

[glenn bradley]

That is almost certainly what is going on with your boards.

If you have hand planes, I've found it very useful to scout out the high points on a board with a straightedge or winding sticks and knocking them down with a hand plane before going to the jointer.

The other thing to try is using more forward pressure and less downward pressure while jointing.

I have also heard folks recommend to take a few swipes on the leading edge without following through. This creates a large flat spot so you can apply feed pressure without pushing the bow out of the board.

Another idea:

http://www.sawmillcreek.org/showthread.php?t=58735