In addition to what Lew said, and one of the key points, as I was taught in woodshop... the best results can be obtained by keeping the majority of any downward pressure necessary to control the stock on the _outfeed_ table.
Maybe we're considering bows and warps of 0.500" or more nd you're talking about a measly 0.004" or something...
-- "The history of temperature change over time is related to the shape of the continents, the shape of the sea floor, the pulling apart of the crust, the stitching back together of the crust, the opening and closing of sea ways, changes in the Earth's orbit, changes in solar energy, supernoval eruptions, comet dust, impacts by comets and asteroids, volcanic activity, bacteria, soil formation, sedimentation, ocean currents, and the chemistry of air. If we humans, in a fit of ego, think we can change these normal planetary processes, then we need stronger medication." --Ian Plimer _Heaven and Earth: Global Warming, the Missing Science_
...
Well, one can only remove cupping to the extent either the material is sufficiently strong to counteract the feed roller down force or is supported on a wedge/sled; otherwise the material is flattened, goes under the cutterhead and then returns to the former shape when the pressure is removed (w/ some reduction in the amount of material in the high places).
One can only remove bow or twist to the point of having a continuous plane of reference of the material to the cutterhead which again will move and rotate as the twist goes under the pressure roller unless the material is constrained.
It's only simply geometry...
Nope.
"Lew Hodgett" wrote in news:4df83dd6$0$1613 $c3e8da3$ snipped-for-privacy@news.astraweb.com:
Thanks Lew. I've got to agree about those plastic paddles with foam. They don't seem to provide any pressure towards the bed at all, which means my board would have a chance to skip or otherwise move.
Puckdropper
Swingman wrote in news:rc-dne71xui7O2XQnZ2dnUVZ snipped-for-privacy@giganews.com:
When jointing a board, the board naturally starts out on the infeed table and at some point pressure would have to be transitioned to the outfeed table. Is this just operator preference, or is there a point along the board where it's best to change from infeed pressure to outfeed pressure?
Puckdropper
I believe we may just have a misunderstanding concerning terminology. A planer will correct cupping, just fine.
It won't correct bow or twist on any board longer than, probably 2 feet. It's just not possible on a normal planer that most woodworkers have in their shops. "Having been a professional machinist and tool maker for the past 25 years," perhaps you've been using a planer with some super long bed and two sets of rollers or something.
I'm hearing some quote from My Cousin Vinnie about Jack and him magic bean stalk means. :-)
Since this group is supposed to be about sharing of ideas and learning and all that, I think it would great of you to share the wisdom of your technique for this process with us lowly ignorant masses. A video would be great.
Otherwise, I'm calling bull$h!t. :-)
Very true. I've also found, concerning downward pressure, the lighter the better. Too much downward pressure and you take the bow out, essentially doing what we're all saying a planer does, removing material from the entire length.
I certainly could use all the (good) planer technique advice I can get, so keep it coming.
Nope.
Yes it is.
Delta 22-560
I have one of those and it has corrected cupping just fine on many occasions but it has never done a damned thing for bow or twist.
Sorry, but you're either mistaken or lying.
Put up or shut, then. Let's see some video.
You can use a sled that will support the warped/twisted/cupped board. The planer will flatten that board.
I would change pressure to the out feed as soon as I could. Basically as soon as the out feed can support the board.
Yes, you can. I want to see his.
Bingo ...
Maybe he's using shims and a sled?
>
An explanation wouldn't it. You would have to see it. The last movie camera I had was a super 8 and will probably be the last one I ever own. No use for it.
Fine with me. Your opinion means less to me than the electrons it takes to send this message.
You going to buy me the camera?
Useful in extreme cases but, if I had a board that bad off I would either carve a propeller or throw it away. In any case, a few minutes with a hand plane and it is flat enough for the planer.
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