Belated addendum to the discussion about adjustable mouths on infill
planes.  Jeff Gorman is right about tightening the mouth using parallel
shims: you can also open it [and increase the pitch] with a shim at the
top of the blade ... no irreversible filing required.

Andy

Jeff Gorman wrote:

> Can be closed, of course, by putting a shim between the blade and the
> frog, or as some people did/do put a strip of leather on the lower
> face of the frog.