Jointer

If the blades are nicked, they need to be sharpened or replaced.

First, replacing knives: I set the tables level at a reasonable height above the cutting head -- the back table adjusts as well as the front. Then I set a pair of bar magnets from table to table to hold the knife in place. Fasten, and go to the next. This takes practice to do well, but it's a simple procedure. If the jointer works well enough with the knives set that way, all the better.

If you want to refine the cut as much as you can, you can "joint" the knives by, believe it or not, running a fine stone across the knives while the machine is running. First set the tables even with each other, and just barely exposing the highest knife. Take a very careful cut by placing a large, fine stone down over the knives, then moving it back and forth across the table. This isn't for the faint of heart the first time, but if you do it right all three knives will have small bevels on them, no bevel will exceed 1/16", and you will still have all your fingers.

Sharpening the knives: I regularly do my 15" planer and six and eight-inch jointer knives on my disk sander with 120 or 180 grit sandpaper. I just set the table for 45 degrees and slap on a small jig made of plexiglass to take up the space between the table and the blade. Then I go at them freehand, grinding until I get a nice, even bevel. This works surprisingly well.

If you plan to plane fine-grained woods like cherry and walnut, put a small additional 5 degree bevel on each knife before installing it. Soft woods cut better with just a single bevel. The angle on the knives is less critical than you might think. The larger the knife, the easier it is on the fingernails, btw. I think I'd buy a couple of sets of 4" knives and save the manicure.

I snug the knives a tad high and use softwood endgrain as a punch to tap them down to the correct height. Correct height measured by standing a 12" steel (from an adjustable square) on edge on the outfeed table. Moving the cutter head so each knife moves the steel the same distance. 3/8" is a good target, but not critical as long as all knives are the same.

The infeed table is of no consequence to the knives as you're going to raise and lower it to adjust how aggressive your cut is.

The other thing you want to check is that your infeed and outfeed tables are in the same plane. Raise your infeed to outfeed height and test a straightedge across both, including diagonal. If the steel won't contact both tables at all points, you need to adjust until it does. Shouldn't get out of whack again until you pick it up to move it, and even then won't if you don't grab the tables.

First time through is the most difficult. BTW, if/when you get a nick in your knives, off-setting one sideways will put you back to work fast. Just make sure the height's the same.

KEH