Fall 2003

Page 9

Center for Essential Education

School of Woodworking Newsletter

With the cutting iron sharpened you must now check the next possible problem area which is the back iron (chip breaker). This simple addition to the cutting iron assembly serves to flex the cutting iron which reduces chatter at the cutting edge, and at the same time directs the shavings up and away from the cutting edge, clearing the path for the cutting edge as the plane advances over the surface of the wood. The chip breaker is formed from a 1/16” thick plate of steel bent in such a way that pressure is applied to the cutting iron directly behind the cutting edge. This back iron must lie against the cutting iron with no gap along the leading edge, between the cutting iron and the back iron, othewise shavings will jam in the crack no matter how small the crack is. If there is a gap, simply lay the iron against the face of the bench stone and rub it a few times to flatten the steel edge as shown. It’s best to undercut the edge a little because the two parts, the cutting iron and the back iron, will flex and bend somewhat when you tighten the set screw. This bend and flex causes a gap on the leading edge of the back iron, which allows the leading edge of the shavings to enter and restrict subsequent shavings from passing through the opening of the throat.

Visually check to see if there is a gap along the leading edge of the back iron; directly behind the cutting edge of the cutting iron. If there is, separate the back iron from the cutting iron and set the cutting iron aside.

The gap along the connecting face of the back iron must be removed by using the coarse bench stone as shown here. Simply rub the back iron against the stone until the leading edge of the underside shines. When you put the back iron and the cutting iron back together, the gap should be gone. The back iron and cutting iron assembly are held together with a single set screw that passes through the cutting iron into the back iron.