There is no single best way to set a bench plane to take a proper shaving. I’ve seen people do it by eye, with their fingertips, using scraps of wood and even working on live stock and making adjustments on the fly. This last technique takes guts. It’s like working on a car while the engine’s running.
I’ve tried every single method above and can do them all with great ease. There is no secret to unlock any particular method. Only practice.
The following is how I prefer to set a bench plane to take a shaving. It’s in more detail than I usually go into on the blog, but here’s the dirty little secret about that: The reason I started writing this blog in 2005 was to create a way for me to answer common e-mail questions. Want to know the difference between bevel-up and bevel-down planes? Instead of answering that question six times a week, I could paste this link into an e-mail six times a week instead. Oh, and the blog would serve as a way to remember when I got my last tetanus shot.
Before we get to the good part, let me shove a little dogma down the disposal with the evening’s chicken bones. All of my bench planes (the fore, jointer and smoothing planes) have irons with curved cutting edges (so does my block plane, but that’s another entry). I camber the cutting edge to keep the corners from digging into the work and to allow me to remove material from selective areas on a board. People who disagree with my approach are encouraged to come to our shop in May for the Lie-Nielsen show with their torches and pitchforks.
The good news is that the way I set a bench plane works for any plane (even joinery planes and moulding planes). So don’t flee yet.
Step One: Kentucky Windage
The goal is to get the iron centered in the mouth of the plane. The strongest part of the curved edge should be in the middle of the mouth, and the corners of the iron should be tucked safely into the body of the plane. If your curve is too pronounced, you’ll take too narrow a shaving. If your curve is too flat, the corners will still dig in.
First you want to sight down the sole of the plane. Gaze at the toe of the sole and advance the iron until it appears as a black line across the sole. If your bench is light in color, you can use the benchtop as a background. If your bench is bubinga, do this against a sheet of paper.
Adjust the iron laterally until the black line appears consistent across the mouth. The camber on a smoothing plane and jointer plane isn’t really visible, so you’re looking for a consistent line.
Use a Scrap to Refine
Retract the iron into the body of the plane and start advancing it. Use a small shim (1/16″ x 3/4″ x 1-1/4″ is nice) and run it across the mouth of the plane as you advance the iron a bit. Where the iron is cutting, you’ll feel it drag against the shim. It’s not dramatic , more like a tug. I first got this trick from David Charlesworth. Thank you, David.
Where do I get my shims? Well you could send me $20 and I’ll send you a bag of them. Or you could look in your garbage can for waste that has fallen off from your rip cuts.
The end result is that you want to feel zero drag at the corners of the mouth and a little drag right at the center. You can adjust the iron using the lateral adjustment lever (if you have one), but I prefer hammer taps using a small Warrington or tack hammer. These are love taps and are unlikely to mushroom your iron. I’ve been tapping one iron on one smoothing plane for about five years. I’ve almost used up the entire iron and still have yet to find a mark from my tapping.
Then I start planing , either on scrap or live stock. Likely the shaving is too thin. And that’s OK. Advance the iron until you get the shaving you want from the plane. Then take a quick look at the shaving and where it is coming from in the mouth.
The shaving should be centered in the plane’s mouth. And the shaving should look like this: It should be thickest in the center and fade away to nothing at the edges. And it should be as wide as possible. That’s the sweet spot.
If I’m a little off-center at this point, I simply tap the iron with my baby hammer to move the shaving into the center of the mouth. Then I get busy.
– Christopher Schwarz