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Discussion Starter · #1 ·
Last week I had my jointer knives sharpened and went about re-installing them. After doing so, I flipped the machine on and it was much louder than normal (I have a 6" Jet jointer w/ the Quick-Set Knives). It had a very violent (for lack of a better term) noise to it and was shaking ever so slightly (typically it NEVER shakes)

I thought that perhaps it was the cutterhead, so I took the knives out and started the jointer up and it ran as well as it always had. A very low-decibel hum that I've grown accustomed to.
What could be making it grind with the knives in? It's odd that the machine runs super quiet without any knives installed; however when I install them it gets this odd, much louder noise.
 

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somethin' ain't balanced

Is this the first time with the quickset knives?
The knife edges should project no more than 3/16" from the cutterhead. A photo would help....
 

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Discussion Starter · #3 ·
This is the first time changing them. I tried to follow the Wood Whisperer's guide to reseating them (using a piece of wood / rubber to force the cams against the blade)

I'll get a photo this weekend - all my tools are at my folks' house.
 

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Check to make sure your knives are centered laterally in the cutter head. If the end of a knife is sticking out too far it can rub on the casting and make a growling noise & vibration.

Brian
 

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Discussion Starter · #5 ·
I was wondering if that might be it. The manual said to let it overhang 1/32"; when you say sticking out too far, do you mean more towards the outside of the jointer or towards the gears?
 

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Either direction will do it. Unplug your machine, drop the infeed table all the way out, and rotate the cutter head by hand very slowly. Look and listen for a slight rub. You'll also be able to feel a rub if you're really paying attention ;-)

Brian
 

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Discussion Starter · #7 ·
Ugh, rookie question here, but when you say "drop the infeed table" do you just mean lower it as far as it can go?
 

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I would take the knives out and put each of them on a scale and weigh them. If they ground an excessive amount off one or more knives it would make the jointer out of balance. It's like when I make shaper knives. I weigh them and make sure both are the same weight. Sometimes just a couple of grams can make a noticeable difference in the way it runs.
 

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I would guess that the knives are not the same weight. There may also be some contact somewhere but the serious vibration almost has to be caused by an out of balance head.
 
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