When I tried woodworking for the first time, the experience almost crushed me under a load of guilt. I was seven years old, and my grandfather had let me use a wooden smoothing plane originally owned by his dad, a British-trained cabinetmaker. Everything was going well until I hit a finishing nail buried in the scrap pine I was practicing on. That accident nicked the blade, of course, inflicting what I thought was permanent damage on the tool. Every time I took another stroke, a long, thin bulge of wood on the otherwise smooth, planed surface reminded me of my transgression.
But wise granddads know how to deal calmly with all the nicks that life dishes out. And it wasn’t long before I witnessed firsthand how to fix my enormous problem by applying skill and patience. Honing out the nick and tuning the plane improved it immensely. The experience also showed me that some things are worth tinkering with.
Hand planes are one of those things. I’ve since learned to tune my own collection of metal hand planes — both old and new — and to experience the satisfaction of watching curls of wood swoosh out of a plane that’s firing on all cylinders.
Although block planes can benefit from most of the tips you’ll read here, their anatomy isn’t exactly the same. But the procedures you’ll read about will help your plane perform optimally for years. When you tune a plane, you’re picking up where the tool factory left off, completing small but important adjustments that usually prove too expensive to do in the commercial arena. After that, all you have to do is keep the blade sharp.
Start with the blade
You can improve a hand plane’s performance in four ways: sharpening the blade, tweaking the cap iron and lever cap, refining the frog and flattening the sole. Sharpening the blade (plane iron) is your first job. You can muddle along with a less-than-flat sole or a frog that’s not as smooth as it should be, but a dull iron turns any plane into nothing more than a fancy paperweight.
Every effective plane iron has a correct bevel angle of 25 to 30 degrees and a finely honed edge that’s capable of cleanly slicing curls of end grain from softwood test blocks. Both the bevel angle and a fine edge work together to create the desired results.
If your plane is new, you can probably skip the first sharpening step — grinding a correct bevel. Factory-new planes usually have this right, though sometimes not much more. But let’s say you’re dealing with an old iron that has seen lots of brutal action, perhaps even opening paint cans or stripping furniture.
Successfully grinding a plane iron like this demands the same machine used for reshaping the business-end of any edge tool: a stationary grinder capable of supporting the plane securely while reshaping its surface with minimal heat buildup. Heat is the tool grinder’s enemy. If the tip of your plane iron becomes yellow or blue because of grinding heat, it will never hold an edge properly again unless you have it retempered by an expert.
Wet grinders can do a great job sharpening planes, but they’re often beyond the average budget and limited in their use for general-purpose grinding. An inexpensive bench grinder can do a great job preparing tools, as long as you upgrade the tool rest. A generous size, easy control over grinding angle and a sliding tool holder are features you’ll find on good tool. Another accessory to consider is a cool-running soft-bond wheel. Except for their white color, these look the same as regular grinding wheels. But the softer consistency means that grinding continually exposes fresh, sharp abrasive particles. These particles remove steel with less friction than the rounded particles that develop on traditional wheels. The result is a cooler grind, though the cool wheels do have a somewhat shorter working life.
Even with a cool-grind wheel, you still need to be careful. Don’t make sparks for more than two or three seconds before dipping the tip of the iron in cold water for five seconds. Repeat the grinding and cooling process until the entire bevel shows an even, fresh surface, with a small burr of rough metal formed at the tip. You can buy a tool for measuring the angle of the bevel or use a sliding T-bevel and protractor.
Honing comes next, and you’ll find a complete description of how to do that using Japanese waterstones in the November/December 2001 issue of HANDY (“Sharpening With Waterstones,” p. 22). Although I have an entire collection of waterstones in my shop, I almost never use them because I’ve discovered a much faster method. I go directly from the grinder to a hard-felt buffing wheel charged with a chromium oxide abrasive compound. All it takes is two minutes to impart a razor edge on the iron. And buffing a slightly dull edge back to exquisite sharpness takes even less time than it does to get the iron out of the plane. Just hold the edge of the plane iron tangent to the wheel as you work, with the tip pointing in the same direction as the wheel rotation. Buff the back and then the bevel and you’re done.
Cap iron and lever cap
As the tip of a sharp plane iron slices wood fibers, the curved leading edge of the cap iron directs those shavings up and out of the tool and gives them their curly shape. To reduce friction, the cap iron should be highly polished and have a tight, gap-free fit against the flat back of the plane iron. If you’ve ever used a plane that regularly plugs up with shavings, it probably means there’s a gap where the cap iron meets the flat back of the plane iron.
Take a close look at this crucial spot. If you see gaps anywhere — even tiny ones — you’ll need to rub the leading edge of the cap iron against a perfectly flat, abrasive surface. This is called lapping.
The ideal lapping surface is a piece of 1/4-in.-thick plate glass. A cast-iron table saw top or jointer bed works well, too. And although you could use a slurry of 180-grit lapping compound and oil for this job, a piece of 220-grit wet/dry silicone-carbide paper (lubricated with light machine oil) works better. Place the leading edge of the cap iron against the abrasive (with the back end riding on the glass but not the paper) and then rub back and forth a dozen times. Wipe the cap iron clean and hold it against the flat side of the plane iron for inspection. If the gaps aren’t completely gone, repeat the lapping process.
Once you’ve eliminated gaps, polish the curved leading edge of the cap iron and the cam face of the lever cap so they both gleam. A smooth surface leads to reduced friction for effortless performance. The hard-felt buffing wheel I use for all my blade honing makes quick work of polishing these parts, too.
Flatten the frog
The frog supports the plane iron during use, but if support isn’t complete, the iron may chatter, leaving a wavy surface on wood. As with most other plane-tuning procedures, the solution involves lapping.
Begin by removing the screws that secure the frog within the plane body. Lift the frog out and brush off all the sawdust. Next, place the working surface of the frog, the one that supports the blade, down against the lapping surface and rub. Some 180-grit carborundum slurry or 220-grit wet/dry paper will be fine. Every few minutes remove the frog, wipe it clean and examine the working surface. If you can’t see that all areas have been touched by the lapping process, rub some more and wipe again. The frog doesn’t have to be shiny, just flat so it can fully support the blade.
Flatten the bottom
Lapping the sole is the final step in plane tuning, and it’s also the most time-consuming. The object is to make the sole perfectly flat, and that’s more important than you might think. Removing just a few thousandths of an inch of metal can correct a convex, concave or twisted sole. A flat sole is more effective at imposing flat surfaces on wood, the job that a plane is made to do.
Start by making a slurry using two level tablespoons of 90-grit carborundum powder and a couple of generous squirts of light machine oil on your lapping surface. This process is messy, so consider using plate glass — otherwise your table saw top will be covered with oily black residue.
Work the plane over the lapping surface in a figure-eight motion, maintaining even pressure and flipping the plane end-over-end every minute. The slurry should be the consistency of melted ice cream. If it’s thicker, add more oil. If it’s thinner, add more abrasive. Work the tool for five minutes; then wipe the plane body clean and examine the surface. High spots appear as dull areas; low spots remain unchanged. Keep working until the entire sole of the plane has developed a dull, even appearance.
Wipe the lapping surface clean; then set it up again with 180-grit carborundum powder and oil. Repeat the figure-eight pattern until the entire surface has a lighter sheen; then it wipe again and repeat with 280-grit and 400-grit carborundum pastes. Although you can call it quits at this stage, polishing the sole on a soft-cloth buffing wheel will make it glide effortlessly over wood.
Club member Steve Maxwell lives on Manitoulin Island, Ontario.