I spent the weekend tuning up my shop and I purchased a the polycarb jointer
jig with magnets from Woodcraft to reset my knives. I have a Sunhill
jointer (like Jet/Grizzly, etc) and the knives are held in place with a
magnet piece that has screws that bind the knives/magnet into place in the
cutterhead. The two pieces sit on a couple of springs (I assume to help
align the knife).
One thing I noticed is that the springs were so strong that the knife
assembly pushed up on my magnet jig. So I ended up lining up the jig first
(on TDC - true dead center) and then putting a block on top of the jig to
hold it down, sliding the knife assembly underneath so the tip of the knife
lined up with the mark on the jig and then secured it.
Once I installed all 3 knives I did the board slide test (as described in
the archives). I put a mark on the board, set the board on the outfeed
table, over the cutterhead as well, and lined the mark up to the end of the
table. As I rotated the cutterhead (using the belt) I found that one knife
moved it about 1/8", the 2nd knife about 1/16" and the third just barely
touched it. Oh, I should probably point out that I aligned the outfeed
table to the first knife before checking the other three (hoping they would
match). So at this point I do get nice flat boards when run through the
jointer, but logic says one of my knives is working harder than the other 2.
So, since I'm not really using the magnets to set the knives (I have to push
down on the jig to keep the springs from pushing the jig up), it's acting as
more of a flat hold down. Ugh.
Here's my question: Is it possible to remove the springs without affecting
the performance of the jointer? By removing the springs it seems that the
jig would perform as it was designed -- to hold the knife assembly UP not
push it down -- thus I would be exerting less pressure on the knives and I
assume I would be able to align them more precisely.
Or do I just keep aligning them over and over until they match with the push
test? I'm I dreaming that that's possible?