giant Cypress

Japanese plane set up - III: Final tweaks

After fitting the blade and setting up the sole, there are only a few things left to get this Japanese plane completely set up, mainly related to the mouth of the plane. The first thing to do is to double check the relationship of the blade to the mouth and throat of the plane. The corners of the edge of the blade should sit just inside the throat. If the corners extend past the sides of the throat, shavings are likely to catch and clog at that point.

There are also a pair of shallow recesses to be cut at the sides of the mouth, which helps with the transition from the front of the mouth to the rear part of the plane. Using a chisel, make a shallow cut down even with the front of the mouth, about 1/32”, and then pare a shallow ramp from the rear part of the plane to the bottom of the cut. This isn’t a necessity, and a plane will work well without these notches, but I’ve seen these notches on nicer Japanese smoothing planes.

How the corners of the blade sit inside the throat and how the notches should appear can be seen in this picture. The blade corner/throat relationship is better seen on the right side. This photo is from a different plane than the one I’ve been tuning up, mainly because the body of the plane I was working on already came with the side notches cut, and they were cut in backwards.

After tuning up these aspects of the mouth, set the blade and take a shaving. With luck, you’ll be making nice shavings at this point. With my plane, the shavings jammed up in the mouth like the Holland Tunnel at 5 PM on the Friday of a holiday weekend.

The throat of the plane right at the mouth is cut to be close to parallel to the top surface of the blade, or parallel to the bevel of the chipbreaker if the plane has one. If everything is perfect, the shaving will pass through uninhibited. In my shop, like Elvis, perfection has left the building, leading to the shaving jam. The easiest way to deal with this is to open up the top of the throat without altering the mouth, so that instead of being parallel, the gap opens up slightly from the mouth to the top of the throat.

I am fairly sure this is not traditional, but I used a mill file for this task. With care, chisels can be used for this task as well, of course.

In filing the throat, I’ve angled the file so that it makes contact with the top of the throat of the plane, but doesn’t touch the mouth at the sole at all. It doesn’t take much to accomplish this task. I only needed a few passes with the file to open up the top of the throat, and the shavings had no problems passing through the plane after that.

The other most likely thing to go wrong at this stage is that when the blade is seated, a downward bulge could form in the sole immediately behind the mouth, which will interfere with the action of the plane. If there are still problems with the plane after addressing the throat, double check that part of the sole and scrape it down some more, if needed.

Finally, put a small chamfer along the sides of the bottom of the plane, and another on the back of the plane where it is hit with a mallet to back the blade out. Check the sides of the plane to make sure that they are still square with the sole of the plane. The very ends of the soles should be square-cornered, which pushes dust out of the way of the plane as it is pulled along the board. An extremely well set up Japanese plane can take a shaving so thin that dust trapped under the contact points of the sole can affect the shaving.

I grabbed a piece of scrap wood to test the plane out. Of course, to make things hard on myself, the first piece of wood I found was a short length of quartersawn white oak. Here’s the obligatory planing money shot.

Not bad, if I do say so myself. I was able to get nice shavings off of scrap pieces of cherry, maple, and pine as well.

Altogether, setting up a Japanese plane is a pretty straightforward procedure. If I wasn’t stopping to take pictures along the way, I would guess that I could have had this plane up and running in about an hour, plus whatever time was needed to sharpen the blade. If you are interested in trying this out, get a cheap used Japanese plane from eBay, and try to get it into working order. These planes probably won’t produce sub-thou shavings, but the process of getting them to working shape is identical to setting up a brand new Japanese plane.