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Saturday, 15 June 2013

Toothed Plane Irons

Toothed plane iron on burr oak
No tearout - none - zip - zilch - nada - zero!

Not even on this lovely piece of dry English burr oak. Go ahead, click on the photo to take a closer look.

How do toothed irons work?
Because the shavings produced are discontinuous, the forces involved in cutting any individual one are proportionally much smaller. They are also much weaker than a full width shaving and break more readily.

What about the lines?
Clearly you still need a well set up smoothing plane or a scraper to bring the board to a finish-ready surface, but the toothed blade will get you through the processes of removing any twist, wind or cupping and bringing the board to dimension, all at full speed and without a second thought for tearout.

Sharpening toothed plane irons is, if anything, easier than sharpening standard ones. Just a flat bevel at 25 degrees and a quick wipe on a leather to remove any burr - job done.

It's the complete opposite of a smoothing plane, you want a wide mouth and the chipbreaker set well back from the cutting edge.

Why not use a back bevelled iron or scraper plane for the whole job?
Back bevelled irons and scapers will both help enormously with tearout prone timber, but the steeper the angle, the harder they are to push. A toothed iron cuts at the same angle as a standard blade, so you can whizz through beautiful gnarly burred timber with no more effort than you would need for straight grained wood.

OK I'm convinced, where can I buy them?