Reply by Brett

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Posted on Corrugated bottom on plane?

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660 posts in 2829 days

#1 posted 05-10-2012 09:50 PM

It may seem counter-intuitive, but grooves shouldn’t have any affect on the amount of friction that a plane experiences when it’s pushed across a board.

Friction force is equal to the downward force (due to gravity plus the force you are exerting on it) times a coefficient that depends only on two materials in contact. For cast iron and oak, that coefficient is 0.49. So, if your plane weighs 7 lbs (like a jointer) and you add 3 pounds of downward force to it, the friction force as the cast iron plane is pushed over an oak board is 4.9 lbs. It doesn’t matter how much or how little contact area there is between the cast iron and wood; the only things that are important are the downward force (10 lbs) and the coefficient of friction. If you put paraffin or a light oil on the sold of your plane, the coefficient will go down, perhaps to as little as 0.075, which means your friction force would be 0.75 lbs.

(Whew—that’s enough geek talk for one day.)

-- More tools, fewer machines.

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