From WoodworkersZone WoodWiki
Stick Method for Jointer Blade Alignment
Procedure for setting jointer knives using a stick
In my experience knife setting jigs and glass with magnets are too fussy and they depend on top dead center, The stick only depends on movement of a known length and that is set by you prior to removing the first knife.
Best of all a stick is cheap....
Please note about this procedure: This is designed and described for moveable out feed table jointers ( not fixed out feed tables) nor for wedging systems that depend on allen screws to wedge the gib in place by raising the gib If you have this style jointer the process still works but you have to go about it in a slightly different way. Contact me if you want further information on proceeding
Before you start
I only remove one knife at a time from the head. If you do not own two sets of knives I strongly urge you to buy a second set before continuing with this endeavor whether you choose to have knives resharpened or just replaced. I feel this is important to keep the head from distorting as you replace the knives.
Get/make a piece of straight hardwood about 3/4 x2"x12" long. Make sure it is straight as it is a reference for all the operations that follow. The stick is always used off the out feed table, it is the reference table for all alignment and cutting operations. I generally lower the in feed table at least 1/4" so it is not in the way.
Take a moment and clean up as much of the dust and chips as you can with compressed air or a vacuum, chips especially on the out feed table can be picked up by the stick and throw off the accuracy of the stick. Unplug the jointer
Now the next step may require lowering the out feed table slightly. The amount is not highly critical but I would try to keep the stick movement between 1/8" and 1/4" as outlined below.
First make a single line on the 2" face of the stick about 2" from one end so you can see it as you work. This is the point that you will start all setting operations. Now set the stick on the out feed table in a location where the knife is still fairly sharp (generally for me this location is on the out board (closest to me facing the jointer side, I try to reserve this area for my most critical cuts) with the starting line set at the edge of the out feed table.
Note in the pic that the knife is set so the knife is closer to the outfeed table, this is the starting point of the knife head each and every time.
The next step is to rotate the knife head toward the in feed table. If the out feed table is set low enough it will pick up the stick and pull it toward the in feed table.
Once the stick stops moving put a hand on top of it to hold it in place and make a second mark. This is your stop point, as long as the stick only moved no less~ than the 1/8" but also less than 1/4" ~ You now have all the information you need to set the new knives. Conversely, If the stick moves much further than 1/4" raise the out feed table up some and repeat the process. I find that if the stick moves too far it is harder to get accurate readings. The same if the movement is less than 1/8" it is too short of a pull (the lines are too close together) and leads to very fussy adjustments. Once you are satisfied with the location of the second line take a square and extend the second mark for easy sighting.
Removing the knife
The first step is to loosen the gib screws so the knife can be removed. Most modern jointers use a series of bolts (four on 6 and 8" jointers more as the units get wider) The correct way to loosen the gib screws is to rotate the heads clockwise or towards the knife ( as one would do to Tighten a bolt against a nut) The reason is of course that the gib has to expand to tighten against the knife and the back of the gib way. Once you have the gib loose remove it and then pull out the knife. To keep things in some order I use a sharpie and mark this knife location on the head as #1. . Clean out the slot and clean up the gib and the screws so that any foreign material has no effect on the gib and the knife. If the head uses springs to lift the knife make sure they are all still there. They are small and get lost occasionally so it pays to look.
A one time added step
I recently added another step to setting knives in a jointer I have not replaced knives in before . When I am changing knives for the first time on a jointer I am flattening the face of the gibs so they are flatter than from the factory. I struggled with one particular knife setup recently and spent many times the normal amount of time it usually takes me to set a knife. Upon taking the time to flatten the face the time was cut back to even less than even I thought was possible. This is worth doing as it only takes a few minutes to accomplish for each gib.
freshly removed from the jointer.
About two minutes of work on a coarse diamond stone
And 5 minutes of work.
The key to this is to flatten the face much the same as you would flatten the back of a hand plane iron. You can see in the second picture how the area on the lower left and the upper area above the second gib screw are still low. I only go until I have the face flattened on the edges the middle does not matter to the effort it would take for a dead flat face.
Replacing a knife
Now You can return to the jointer and set a fresh knife in the slot and reinstall the gib bar into it slot and run the screws out so they are just snug across the knife. this prevents the knife from swimming around in the slot as you raise the knife upward If you have springs instead of jack (lifting) screws the knife has to be a bit looser than if using the jack screws. If your jointer has both springs and screws I suggest you use the jack screws over the springs . they tend to be easier to adjust.
After you have the screws all lightly snugged down, put your stick on the out feed table. I always start with the stick near the fence. Rotate the knife head toward the out feed table and set your start reference mark on the stick right at the edge of the table the same as you did when you set up the start point of the stick.
Next rotate the knife and the head and when the stick note the position of the stick's movement. If the stick did not move at all or did not reach the second mark then the knife is too low and requires adjustment upward I actually prefer to move the knife upward to gain the required height over lowering the knife. If I must lower the knife I will take the rear end of the setting stick set it on the knife ( I lower the jack screws 1/2~1 turn first) and tap the knife downward using the stick and a mallet or hammer. Even if you lower the knife low too much it is not hard to gain back the loss and the knife is being pushed upward positively.
A knife set too low.
Conversely if the stick moves past the second mark the knife is too high and the jack screws will need to be lowered to lower the knife.
Knife set too high
Before I get too far along in all this I move the stick toward me ( to the out board side) and repeat the above procedure so the knife is roughly set in parallel to the out feed table. I find that if I do not do this and the knife is canted at the opposite end (not parallel across the out feed table) setting is harder to accomplish. When you go to fine adjusting the knife the job is just easier.
Once I have the knife position set so it moves from the start line to the stop line I know I am very close to being done.
The knife set perfectly.
Now to finish tightening the bolts on the gib. I start by snugging each bolt just a little I start with the second bolt from the fence snug it some, move to the 4th (outboard ) bolt snug it some, go back to the inboard (1st) bolt snug it some, then finish off on the third bolt. I then repeat using the same procedure (2,4,1,3)
Before I completely tighten the bolts I will take the stick again check both the inboard and out board movement to verify the knife did not slip while tightening the bolts. This is a common occurrence especially if you do not flatten the gib faces. Once again I feel it speeds and simplifies the entire process so I encourage you to do this simple task first. If the knife did indeed move, loosen the gib bolts and readjust accordingly.
If the stick stops at the second line then the knife is parallel ACROSS the width of the blade and probably does not need any more adjustment. You can check the knife in a couple of more places and I would on jointers wider than 8" to make sure the knife is not being forced higher or lower by the gib screws. If all is well then finalize the tightening of the screws.
The rest of the knife change is to just repeat the above procedure for each knife, and then once completed with all the knives reset the outfeed table to the proper height.
[1] The procedure for doing this is in the link shown to the left
Joe
