Reply To: Hollows and Rounds
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If you want to buy them, two useful videos are “Hollows and rounds” by Tod Herrli and “Sharpening profiled hand tools.”
The basic idea is to put layout fluid on the back of the blade, load the blade into the plane and tap in the wedge. Now take a scribe and trace the profile of the sole into the layout fluid. It is important to understand that, when you look at the profile of the blade at 90 degrees, it is not equal to the profile of the sole because the blade is laying down at an angle. So, for hollows and rounds, the shape of the profile is more like an ellipse. By loading the iron and tracing the sole, you do not need to think about any of this. You’ll get the right thing.
Next, grind the iron to shape, just shy of the line, working with the iron at approximately 90 degrees to the grinder. This keeps the edge of the iron thick while shaping, reducing the chances of overheating the edge. When you are at shape and just shy of the line, angle the grinder support so that you grind your bevel, ending at your line.
You have two choices. Some people will oh-so-slightly feather the iron on hollows and rounds, just like you do with a smoother, so that the shaving goes to nothing at the edge. Others keep the profile exactly the same.
On a hollow (cuts a convex surface), yes, you’d use a grinding wheel wth a rounded profile.
I don’t have as much experience as it might sound…I’ve made exactly one hollow (with Tod), but this is how we did it. If you only need to learn how to shape and sharpen rather than make the plane, I think “Sharpening profiled hand tools” covers more ground.
By the way, if you are not making an iron from scratch and are tuning up an iron that is pretty close, you may just be able to shape, grind, and hone using some slip stones.