It is pretty rate to see a infill plane with an adjustable mouth. But I wanted one for several reasons: I don’t know what the “optimum” mouth width is, or if there is one (I suspect it differs for different woods), I think it would be pretty cool to be able to take a thick shaving with infill, this plane is big enough to be a small jack plane, I figured I would probably screw up if I tried to make a fixed mouth. Plus, I’m not convinced about the utility/advantages of a super thin mouth and now I can experiment.
Here are two mouth settings (I can go under zero but that is the max for a 1/4” iron).
If you look at the big pictures, you’ll notice that the iron needs some serious attention (nicks) and has a [unintentional] slight camber.
Adjusting the mouth is easy, something I didn’t realize when I designed it and can be done with the iron installed:
1) Remove iron, loosen the frog screws and close the mouth.
2) Barely snug the screws.
3) Insert iron (it won’t go all the way though) and start to tighten the lever cap screw.
4) As you tighten the cap, the frog will slide back, stop when the mouth is the right width.
5) Remove the iron and tighten the frog screws.
6) Install iron, set depth and remove wood.
Here is an example cuts taken with the two mouth settings. Same piece of wood, a easy to plane 1” softwood. It was all I could do to take the thick shaving, really hard to push the plane. Then again, it wasn’t any easier with a Stanley Bedrock.