2 questions on how a planer actually works..

11 Feb 2011
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United Kingdom
I'm puzzled by how a planer works to flatten timber that is either bowed or irregular. Here are my two questions:

1) How does it work in the first place? - if I have a bowing length of wood, as I feed it through the planer, why won't the planer still just take a slither of wood across the entire length and hence still by bowing?

I can understand if you feed the wood so it's concaved to the blades, then the two ends will be cut away on the first pass, then on successive passes, you end up working from the end to the middle leaving a straight face, but that assumes a long enough flat table top either side of the blades, but how does a typical compact bench top one work where the table top is fairly short then?

2) In feeding the wood across the cutter head, presumably the hand force you use to press the wood down (so it doesn't shoot off the blade) will also dictate the quality/flatness of the final surface, i.e. if it's again bowed concaved, you can probably easily push down on it to hit the blade, but isn't there a good chance that the final surface will still bowed as it springs back after it's been passed through?

Clearly you can tell I have never used a planer before. I want to buy one but need to understand the mechanics before deciding whether a bench top of freestanding one will be better for me

Thanks as always..
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bow up it will nibble the front and back
next pass a bit more front and back

plan the bowed bits for the shortest components and cut to length and plane individual components
if you cut a bowed timber in half you reduce the problem by around 80%
in other words if you have a 25mm bow when you cut in half the bow in each half will be around 5mm
There are a variety of planes , not all have flat blades. Heavily bowed timber cannot be recified with a plane.
The planes main use is to give a smooth face to sawn timber.
A jack plane [curved blade] can be used with skill to take out irregularities.
The plane is just one tool and has it's limitations.
When buying timber should avoid timber with bows or twists since rectifying it could drastically reduce it's size and therefor usefullness.
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Taking out any bow/twist on a planer/jointer, involves as much skill as doing the same with a hand plane. Bow is best worked out by placing the heel section of the affected board first, after dressing that first high spot turning the board end to end and repeat. This can be repeated for very badly bowed boards, then you should have two faces in the same plane allowing a full face pass over the blades which if the machine tables are set properly will result in a flat board. Here's a video to help you understand -http://www.tauntonworkshops.com/course/getting-most-your-jointer-and-planer ...pinenot :)

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