A friend of mine has an old 8" Delta jointer, circa 1952 (the old Crescent
4-blade machine), on which we've been trying to install sharpened blades,
and we've been having a hell of a time getting them adjusted.
For starters, there are a couple of critical tools missing - the special
t-handled wrench for moving the blades up in the holders, and a small jig to
set the height. A screwdriver works sort of OK as a substitude for the
wrench, and we've been using a combination of a straightedge and a depth
micrometer across the two tables, which we adjusted to the same height with
The problem, of course, is that you can chase your tail on a blade for a
couple of hours, levering it up with the screwdriver, tapping it down with a
soft metal rod (taking the honed edge off the blade after a while where you
tap it, naturally). A few thousandths too high, then a few thousandths too
low, back and forth, up and down. Finally you decide it's good enough and
tighten down the wedge nuts, and the wedge nuts raise the blade back up a
thousandth or two or three, generally not the same on both ends of the
blade, because you can't keep the throat block up tight against its pins
while you're fiddling with the blade height. Naturally, on a machine this
old, there are no springs to hold the blade up or micrometer bolts to
fine-tune the blade height.
After about four hours of levering and tapping and cursing, we got all four
blades as good as we thought we could get them without losing our minds. On
one end of the cutter head, the difference between the highest and lowest is
0.004 inch, and on the other end the difference is 0.003 inch, with the
highest blade the same (thank god) on both ends. We took a pass with an
already-smooth piece of cherry that had just been planed in a well-tuned
planer, and I have to say that it felt pretty good.
But I'd like to think that we should be able to get the blades the same
height within a thousandth, and ought to be able to perform the whole
operation in no more than a half hour at worst.
Before you ask, my buddy borrowed a magnetic jig for adjusting planer
blades, but we couldn't get it to fit on the cutter head of this particular
machine. I've also been to the Old Woodworking Tools site and studied the
Crescent section for tips. A Google groups search turned up not too much
except some belly-aching about adjusting similar machines.
What do you think? Did we get it as good as it needs to get? Better than it
needs to be? How would you do this in a half-hour instead of a half-day?