This month I’m writing about one of Lie-Nielsen’s smallest planes, the Convex Sole Block Plane. Don’t discount the size though, as it can be as handy as any other plane in the lineup.
The Convex Sole Block Plane is similar to other planes, in that it has a ductile cast iron body, an A-2 steel iron and a bronze cap. The sole of the plane is 3 1/2” long, and the overall length, including the squirrel tail handle, is 5”. Not all block planes have squirrel tails, but since this plane is small, the tail really makes it much easier to hold comfortably. On most block planes, the sole is flat both side-to-side and front to back. Not on this plane. The sole on this plane is convex both side-to-side and front to back (This means if you set the plane down on one of it’s sides, the bottom bows out in width and length). This Plane is bedded at 20 degrees, with the iron bevel up. The sole radius is 3” side-to-side and 27” front to back, and the mouth has a radius of 15/16”. The radius of the cutting edge of the iron is 7/8”, which prevents the corners of the iron from engaging the wood, as long as the iron is set for a light to medium cut.
This shape of plane is very handy when working on any project that has a concave recess, like a seat for a chair, or even some of the shaping that goes into making the top for a Les Paul guitar (originated by Gibson Guitar Corp.), for instance. Some woodworkers will gravitate towards some type of gouge to work concave shapes, but there is something about the control this plane provides, and the surface it leaves, that makes this such a valuable piece for your tool kit. Even if I use a gouge for the bulk removal of a concave shape, I like to follow it up with this plane, which provides a finalized surface, and the results look and feel so much better than when I use sandpaper.
Sharpening this plane’s iron is a bit different from sharpening a typical flat-soled plane. You start by honing the back of the iron much the same way you would an iron from most other planes. Start with a 1000 grit water stone and then move up to 8000 grit. The main difference is, since the end of this iron is essentially a section of a circle, rather than straight across, you won’t use the Charlesworth ruler trick for this one. I work with the back of the iron flat on the stones, and it usually takes a little longer to fully hone the back the first time. Subsequent sharpening requires very little attention to the back, so the time spent on the first sharpening is a one-time thing. I also limit how much iron extends onto the stone, so it reaches no more than half way across, and depending on the stone size, I may not even reach the half way mark. There is no reason to work the complete back of the iron, as the only section that is cutting is the very edge. Just make sure enough iron is extended onto the stone so you can feel your reference. If you tried to hone something silly-small like a 1/16”, at the tip of the iron, it would be almost impossible to feel that the iron was actually flat on the stone.
Once you finish working the back, shift to the bevel side, for which the steps are also a bit different. To hone the plane iron’s bevel, start by creating a groove in some soft wood, and then set the plane to make a deeper cut than normal. Expect it to take multiple passes, and either focus on keeping the plane’s centerline aligned with your groove’s centerline, or tack a straight strip of wood onto the board to use as a fence. My preference is to make at least a couple of these “pattern” boards, if I plan to use multiple “grits” of honing compound. This way I can maintain each board for a specific grit, and just mark each one for the type of compound used. After creating the groove in the board, apply the compound to the groove. Now, with the iron out of the plane body, orient the iron so the bevel matches the curvature of the groove. Next, I like to mark the bevel of the iron with a black Sharpie marker. This provides feedback so I can immediately tell that I’m working the correct area of the iron. Work the bevel through the compounds, until the full bevel is polished, or at minimum, the leading edge is polished.
Once the iron is sharp, it’s time to re-assemble and put the tool to work. Once the iron is in the plane, lightly snug up the bronze cap, just so it is tight enough that the iron doesn’t move around. I like to set the plane on a flat piece of wood, so the mouth of the plane is the point where the body is resting. While holding the body, I put just a bit of pressure on the back of the iron, so the iron is making contact with the wood. Tighten the cap a bit more, and then see if the iron is engaging properly. If the iron needs further adjustment forward or laterally, make sure the cap isn’t too tight, then tap the blade lightly until the cut is to your liking. Make sure to tighten the cap once you’ve dialed in the cut.
Go give the Convex Sole Block Plane plane a try. I think you just might find it a missing piece from your kit.
I hope this helps answer any questions. Please let me know if you have any specific questions I may have missed.
Click to take a closer look at the Lie-Nielsen Convex Sole Block Plane.
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Lee Laird has enjoyed woodworking for over 20 years. He is retired from the U.S.P.S. and works for Lie-Nielsen Toolworks as a show staff member, demonstrating tools and training customers. You can email him at email@example.com.