Setting Planer Knives

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Forum topic by mwarning posted 10-29-2017 10:55 AM 749 views 0 times favorited 5 replies Add to Favorites Watch
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16 posts in 1158 days

10-29-2017 10:55 AM

Today I’m hoping to give my new-to-me Jet 15” planer a once over and get it in tip-top shape.

I’m going to go over it and make sure everything is dialed in. I only have an old photocopy of the manual to go by, but am taking cues from a better Grizzly manual for a machine that looks virtually identical. I’ve changed the gear oil which by my guess had never been changed and have lubricated everything else. Now I’m planning to check alignment etc, but before I do that I want to install a fresh set of knives that I purchased for it and have run into my first issue.

The Jet manual says the knives should be set so they are flush with the bottom protrusion of the knife setting gauge. I started with the first knife but quickly noticed that the height of the currently installed knives does not appear to be correct according to the manual (ie. the height of the knife is not set so that its flush with the center protrusion in the guide). You can see in the second photo below, how far the knifes protrudes from the cutter head. If I follow the manual, the blade sits much closer to the head, with only a small amount of the knife showing. So I’m assuming I should switch it back and follow the instructions in the manual. However, I’m curious as I’m sure the previous owner used it like this for years—whether it really matters as long as all knives are set at the same height?

Current height of blade in relation to guide:


5 replies so far

View Fred Hargis's profile

Fred Hargis

6243 posts in 3267 days

#1 posted 10-29-2017 11:24 AM

It’s most important they are all the same height, and I would use what the manual says. It is possible you have to adjust the rollers as well…check the manual. Interesting you got the knife setting jig with it…those usually get lost fairly quickly.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Holbs's profile


2346 posts in 2803 days

#2 posted 10-29-2017 01:56 PM
my Jet 15” planer knife height setting

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter "xylokopos/ξυλοκὀπος"

View Aj2's profile


3084 posts in 2572 days

#3 posted 10-29-2017 03:33 PM

Something looks off the me too.Maybe the knive are ground too steep past 50 degrees or they are too thick. Never assume the guy you bought it from had the right knife set up.
Good Luck

-- Aj

View mwarning's profile


16 posts in 1158 days

#4 posted 10-29-2017 05:22 PM

Ok. So I started to install the new knives. I need some advice on how fanatical to be…

I spent 2 hours so far trying to get the first two knives installed. First setting things with the knife setting jig and then checking with a dial indicator in three spots on each knife.

This is what I have so far (measurement from cutter head body to highest point of each knife in 3 locations – left, center, right)

Blade 1: 0.064 0.065 0.067
Blade 2: 0.066 0.069 0.066

I guess I’m asking is how good is good enough. The Jet manual doesn’t say anything. A Grizzly manual says no more than 0.004 from side to side. I’m not sure why blade two rises 0.003 in the middle—It’s a new knife and I can’t believe I put enough pressure on each end to bend it… but who knows….

Anyhow… how does this look?

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Fred Hargis

6243 posts in 3267 days

#5 posted 10-29-2017 06:11 PM

I would call that good. It may be as you see because the edge of the knife isn’t perfectly straight. The proof will be when you stick a piece of wood in it, but that looks awfully good to me; the variation is .005 (low point on #1 to high point of #2) so try to stay that close with the last one.

-- Our village hasn't lost it's idiot, he was elected to congress.

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