I reset my jointer knives after I had them sharpened and here's my issue...

I bought a 50" Lee Valley aluminum straight edge.

I have my knives set so well that when i put the straight edge on the edge of board I jointed, it's perfect, no light shining through.

But! When i face jointed, i put the sraight edge on a board thats 64" long, i end up with a gap of almost 1/16" in the middle of the straight edge.

When I did the face jointing... As soon as my hands passed the blade onto the outfred table, my hands stayed on that side for the rest of the cut. I heard it cutting the entire way. I even drew a squiggly line down the entire board to ensure it was cutting the entire piece the whole way and it was. What could be the reason why i have a perfectly straight edge, but I cant seem to get a perfectly straight and flat face? The board started out about 1" thick.

Thx!

Where are you jointing the board edge? My suspicion is that it is at the back or front edge of the knives.

There is a good chance that the knives are set properly, and the tables aligned properly, at a single point on the knife width. As such you get a good cut when using that specific point on the knives.

A face cut uses the full width of the knives. Unless all three knives project evenly above the cutter head exactly the same amount, and the outfeed table is exactly lined up with the knives at the high point of their cutting arc, you will not get a straight face jointed board.

When I set jointer knives I first make sure they are all the same distance above the cutter head. I use a short straight board on edge on the outfeed table. This short board extends back across the cutter head.

The machine is of course unplugged from the power source in this whole process.

With the outfeed table set too low I rotate the head by hand. As a knife gets to the top of the arc it grabs the stick and moves it a 1/4" or so. With a mark on the board where it intersects the edge of the outfeed table by the cutter head before being moved, and a second mark made where the movement ends I have recorded how far the stick has moved. I then compare this on both ends of all the knives and adjust knife height until all the knives are the same height and parallel to the table surface. I know this is the case because the stick moves the same distance at both ends of all the knives.

When this adjustment is complete I then raise the outfeed table until the knives just kiss the bottom of the stick as they swing by below. I also check this at both ends of all the knives. When everything is just right the knives are all at the same height, parallel to the outfeed table, and at the same height as the outfeed table.

When done with all this I plug the jointer back in and cut the lead couple inches of an approx. 18" long stick. If everything is set up correctly this stick will not catch on the leading edge of the outfeed table, or be gapped above the table.

Turning the jointer off and seeing if the jointed lead edge of the stick hits the table edge anywhere along the knife width when slid forward and back will confirm a good aligment. If the tip of the stick hits on the edge of the outfeed table then that table is too high. If there is a gap between the bottom of the stick and the outfeed table it is too low.

This is somewhat time consuming but a sure fire way to make sure everything is aligned correctly. If the outfeed table isn't set correctly to match properly installed knives you will end up with boards that are bowed in length.

BH Davis

Bh, thank you so much! I have a powermatic 54a 6" long bed jointer. Ive had the jointer for years but never replaced the blades until recently, as i didnt use it a whole heck of a lot. So, i have never messed with moving the outfeed table. When i move the outfeed table, will it stay parallel or is there a chance it could tilt? I dont want to screw it up more than i already have. I have cmt's dial indicators but cant seem to find them right now. I also bought an aluminum straight edge, 50" long, by lee valley. Im about to pull out what little hair i have left

Mike,

The outfeed table will not twist when raising and lowering unless there is serious wear in the mechanism. Since you never moved it that probably will not be a problem unless it was an abused used machine when you bought it. If it is like my PM jointer then both the infeed and outfeed tables ride one dovetail ways with gibs.

It looks like your knives just are not set properly. Put away that aluminum straight edge and use that nice straight wood stick you jointed earlier. Take your time and follow the above instructions. It should take about an hour for a first timer.

BH Davis

These are the dial indicators i bought but ive been struggling to find a good youtube vid on how to use them. I unfortunately took out the knives before i checked their factory set height

http://www.amazon.com/CMT792-Magnetic-Knife-Setting-Jigs/dp/B000P4HO3M

Yes......nice setting gauges. I have similar items. The problem with fixtures like that is the knives shift upward as the gibs are tightened. It takes a lot of practice to get knives set correctly with those "easy use" fixtures.

Put them away and use the stick method as I described. Full proof method of setting knives. Post any questions where I haven't been clear enough in my explanation.

BH Davis

Are these the two things i need to adjust to move my outfeed table?

View higher quality, full size image (3264 X 2448)

I'm putting my money on your technique is causing the problem. The board is more likely to bend when machining the face than the edge. You are putting too much pressure on the face of the board, or you are moving your hands back and forth over the cutter head while feeding it. If you only have changed the knives after years of having the machine, I suspect you may not know proper technique. Start the board over the head, as soon as you can place force down on the out feed table, never move your hands back to the indeed side.

You should be able to adjust the outfeed table height just as you adjust the height of the infeed table. If not there is probably one of the flip tab locking screws on both sides of the jointer body. Loosen both and look for a hand wheel of some sort that slides the table up and down the dovetail way slope.

BH Davis

On the attached photo of a new Powermatic model you'll see the outfeed table adjustment hand knob on the left. You have to loosen the lock handle on the outfeed table first. There may be a lock handle on both front and back of the machine.

If you don't already have one you really should search out a manual for the machine. It would help you out significantly in matters like this.

BH Davis

View higher quality, full size image (1085 X 663)

Check the unjointed side of the board to see if it has a gap on each end of the board. You may be relieving stress in the board as you joint it causing it to bow.

Just a quick comment here...the head on the 54A is the worst design for a head EVER and you have to buy their knives and you cant get carbide tipped. The cams are a major pain to adjust.

I never moved the outfeed table on any of my jointers...play with the knives you want them about .003 above the outfeed table.