Originally Posted by
Rafael Herrera
In those planing competitions they use a very particular type of wood, I think it's straight grained alaskan cedar. Whatever the wood they use it's a very particular kind and lends itself to the very thin shavings seen there.
I don't know how they setup those planes, but since the wood they use is a big part of the results they get, whether the mouth is tight or not is probably of little consequence.
I've tried to take very thin shavings off of regular wood species, with the grain, with the iron as sharp as I could get it. I think I got as thin as 10 or 15 micrometers in some cases. It was an interesting experiment, but totally useless for real work.
If the chipbreaker is close to the edge, there needs to be room for the shavings to pass. If you want to set the plane to take shavings thicker than .001", there needs to be room for the shavings to pass.
It does not take much to confirm this. Set the frog back so you can see through the mouth when the double iron is installed. Take some shavings at different thicknesses. Examine the quality of the surface produced.
Next, close the mouth and watch your plane clog.