Chatter marks from Jointer

[Bollox]

Hi guys,
Lately I've been getting "chatter" marks when using my 6" jointer.
It happens both when edge jointing and face jointing. I dont think it is grain direction, the blades are reasonably new and sharp, Ive checked blade height (all within .002" of each other), the tables seem to be coplanar, raising or lowering the outfeed table doesnt seem to help.
Anything I havent thought of? or have I suddenly picked up some bad technique?
Thanks
Mike

[Tom Slick]

your outfeed table should be exactly level with your knives, but I don't think that is your problem. what is your infeed table set to? are the belts tight? does the type of wood make any difference? how old is the jointer, could the bearings be bad?

[jabe]

Most often this is caused when you're pushing your wood too fast and not giving the blades enought time to cut. Try slowing down and cut with the grain direction. Another mistake people often do on the jointer is to push down hard on the wood, do not push down, usually light pressure and the weight of the wood is enought. If that doesn't work then I would check all the other adjustments and joint the knives so they become the same height. Your owner's manuel should show you the procedure to joint the knives. Hope this helps.

[LCHIEN]

I'm thinking too fast a feed rate or too deep a cut. I usually use 1/32" or less, never more than 1/16th".

[Bollox]

Thanks guys,
Its too cold tonight to play around too much, but I rechecked my measurements (the depth of cut was about .028", less than 1/32 of an inch), and I reset the outfeed table to be the same height as the knives (I seem to remember reading somewhere that some one recommended setting the outfeed table slightly lower(?) than the knives). The belt was a little too loose so I tightened that up (the belt gaurd kinda discourages you from easily checking this without unbolting something).
The machine seems to cut a lot smoother now.
Of course I could have subconsciously changed my rate of feed, or the amount of downward pressure I put on the board, but I tried to put it through the same as I always have.
My gut feeling is that it was the belt tension that made the difference.
Thanks again.
Mike

[Tom Slick]

you'll get snipe if your outfeed table is lower then your knives.

[SARGE..g-47]

"It happens both when edge jointing and face jointing. I dont think it is grain direction, the blades are reasonably new and sharp, Ive checked blade height (all within .002" of each other), the tables seem to be coplanar, raising or lowering the outfeed table doesnt seem to help".. Mike

New blades properly set, not too deep a cut, tables properly set, not too fast a feed, pullies aligned.... hmmmm!

With all thing considered, I agree that the belt tension may have been the cuplrit. If the belt loosens and slips on the pulleys, it is equilavant to missing a heart-beat. Not life threatening, but not a perfect scenario either as it will cause chatter with the blades making contact at ir-regular intervals.

Have to agree with Tom about the out-feed being to low.. or high for that matter. Text-book says perfectly aligned with top of blade, but I will go slightly against the grain on that one from my experiences. Perfectly aligned to the best of my ability and the ability of the straight edge I use to get there. Running scrap stock through at that point, if there is any chatter visible I will raise or lower the out-feed a nana-hair (and that's why I like hand-wheels as opposed to levers) till it goes away on that machine.

I have seen some jointers that made a better cut with what appeared to be a .001 or so lower and some that appeared to be .001 or so higher according to a straight-edge. Each machine is different IMO and I let the machine dictate what is the correct height for it's out-feed for maximum performance.

Whisper in my ear, sweet-heart.. I'm carefully listening to what makes you tick!

:>) ..... ha.. ha...