I have set planer blades on my Scheppach 260 with no problem for about 20 years using the same method and it gives a consistently good results and finish This is a two cutter block using HSS knives and grub screw adjusted. not spring loaded, so its not appropriate for me to comment on spring loaded, or reversible blade setups because I have not set up using these systems more than once or twice.
First thing I do is disconnect it from the power.
Next, after removing the blades/knives is to give the channels and wedge bars a good clean out with resin remover and fine wire wool to clean everything including the threads on the grub screws and blow the dust away from where the cutter block shaft leads into the bearing housings. any build up of resin or even rust here has a chance to begin to interfere with the seals of the bearings and once the seals are breached the bearing life is compromised.small point but pays off in the long run.
When everything is cleaned up and after a wipe down with light machine oil the knives and wedge bars go back into place ensuring that the wedge bars always go back into the channel that they came from......Yes, they should all be the same and interchangeable but if you want to experiment with balance and vibration go ahead, I stick to how the factory set them up......The factory set up has small weight reduction balancing holes drilled out in some, and these are for a reason.
Next is to bring the knives up to something like the position they should be in/ I always start with the outer two adjusters so the knife is roughly equal and level then bring the inner adjusters up to just make contact with the back of the knife.
Next a piece of 2x1 or anything handy that is roughly flat. laid across the outfeed table and straddling the cutter block for an inch or two and turn the block over TDC .This should be done alternatively at each end of the cutter block if the 2x1 moves say an inch or so then lower the knife at that end and if it fails to move when the cutter block is rotated then raise the knife at that end....Keep doing this until the movement at either end is minimal. tighten the knife locking bolts when the movement of the 2x1 is about 1/8" when the blade drags it as the cutter block is rotated over TDC at both ends
Carry adjusting on until both ends move the timber an equal amount, about 1/8" dragged forward for each end of the block. Making sure that you are turning the knives in the cutting direction of course!
Now replace the 2x1 with a steel rule. place the steel rule on the outfeed table overhanging the cutter block with an reference point aligned with the very edge of the outfeed table, it doesn`t matter at which point of the rule , its the amount it gets dragged forward when you turn the block as before that is important. Aim for between 1/16 and 1/8 " movement, the critical thing is to get the same result at both ends, and assuming the knives and tables are true then this "reading" should be the same along the whole width of the table.
Follow the same procedure for the next knife set up, aiming for the same amount of "drag" movement as the first knife, making sure that the locking nuts are tightened fully on each trial set up so you do not get a false reading
When you are happy that the movement of the test piece/rule is the same on all fully tightened knives when dragged over TDC then ensure all locking bolts are fully tightened ( You only ever need one planer knife spinning through the air at 20,000 RPM to remind you of the importance of this final check ) and set the guard over the cutter block. and power up.
If all is well at this point then you should get a good consistent cut with no surprise variations along the length of the work piece, especially at the beginning and end.
and never mix knives.......always use equally ground pairs of the same type and make
