This article is from the Woodworking FAQ Collection 3, by multiple authors.
From: email@example.com (John O'Brien (x37279))
Date: Tue, 4 Aug 1992 12:17:10 GMT
I finally had my jointer knives sharpened for my 6" Craftsman jointer
and set about re-installing the knives last night. The instructions call
for the knives to be about .003" above the outfeed table and outlined
a fairly straight forward method for adjusting for this tolerance. I
took my time and set each knife to approximately 3 or 4 thousandths.
It was virtualy impossible to get it exact due to the courseness of the
depth adjustment screws. But, what is 1/1000" going to make anyways, right?
After rechecking everything I jointed a couple of boards and noticed that
the very last inch seemed to be cutting more than the rest of the board.
This was quite noticeable when looking at the edge of the board and even
more so when planing boards on the jointer. Hence, I went about the task
of re-adjusting all three knives to the point where they are now onlt
.0015" above the table. I have
used a couple of procedures to determine this height and felt good about the
accuracy. I again ran a few sample cuts and again heard it cut more on
the tail end (1") and by examining the board's edge it was evident the
problem still existed, only not as bad.
When jointing 2 boards together, this indentation in the boards edge
is multiplied and I end up with a .003" gap where this occurs. A .003"
gap is quite noticeable when edge joining boards so this is unacceptable.
My questions to my jointer literate friends on the net are:
Is Sears' recommendation of setting the knives .003" higher than
the outfeed bed incorrect?
Is there something else wrong with my setup? I don't remember
having this problem before removing the knives and they were set at
about the same height before removing?
Do more expensive better built jointers have a more sophisticated
adjustment mechanism whereby setting can be adjusted to the .0005", which I
would think is acceptable?
My last question has to do with planing a cupped board on the
jointer. By planing the concave(hollow) part, I was able to trim off the edges
evenly to allow for a flat surface. However, upon attempting to plane the
other surface resulted in a 2 sided surface, depending on which way the board
rocked as I planed it. What procedure should be followed when planing a cupped
board on the jointer?