Lost Art Press

This week I’m deep into reading Joseph Moxon’s “Mechnick Exercises” – the first English-language treatise on the craft of joinery. Published in 1678, the “Exercises” cataloged the tools and practices of the blacksmith, joiner, house carpenter, turner, bricklayer and those who make sundials.

For the modern reader, the book can be a horrible slog. The printed English word of the 17th century seems convoluted. Sentences run on for far longer than we are accustomed to, and the sentences are interrupted by asides that wander a bit. Then they’ll insert a reminder of the original point of the sentence and swoop in on the end of the phrase.

Truth be told, you get used to it after a few pages. Then the hardest thing becomes the occasional unfamiliar word – for example, “dawks” means “hollows” – and the odd tool. My favorite example: the pricker. The pricker is a marking tool that perhaps resembles a square-shanked awl. But in Moxon’s glossary he says the vulgar term is “awl” and instead the proper word is “pricker.”

So as of today, the filthy word “awl” has been banished from our shop in favor of the much more polite “pricker.”

Every time I read Moxon I learn something interesting and useful. But what is most fascinating is how little has changed in 330 years. The tools and the methods are familiar – once you strip away the “shall yets.” Except for one important difference.

What strikes me during this reading of Moxon is his affection for the fore plane – a tool that is typically 16” long, which is shorter than jointer plane and longer than a jack plane. The fore plane has a blade with an obvious curve and is used to quickly remove material.

Moxon spills more ink on the fore plane and its use than he does on any other single plane. He discusses how it is used with its iron set both rank and fine. How it is moved across the board. How it trues faces and edges. The jointer plane gets some discussion, but not nearly as much as the fore.

And then there’s the discussion of the smoothing plane. Here is the entire entry on the smoothing plane (cleaned up a tad):

“The smoothing plane marked B 4. must have its iron set very fine, because its office is to smooth the work from those irregularities the fore plane made.”

That’s really about it. There’s no protracted discussion of the smoother and wispy shavings or strategies to reduce tear-out (though Moxon suggests that high planing angles are important in one part of the book).

Our obsession with smoothing planes might be thoroughly modern. Or perhaps there’s another way to look at this (bear with me, I know this is getting long).

Recently we had Matt Grisley from Leigh Industries in our shop to demonstrate his company’s new dovetail jigs. During our day together, he made an astute observation about hand work. I wrote it down after he said it. And it went something like this:

“What’s interesting to me is how woodworkers who love hand tools also love the heavy machinery – the big planers, jointers and table saws. And they don’t seem to have much affection for the power hand tools, like the router and biscuit joiner.”

And he’s right. I am deeply indebted to my planer and jointer. I would get rid of five of my smoothing planes before I got rid of my jointer and planer (don’t worry I’d still have at least five smoothers left).

I am obsessed with my heavy machinery like Moxon’s workmen were attached to their fore planes. For these are the tools that get the brute work done, that make woodworking possible. The finesse work stands on the shoulders of the fore plane and machinery. Now if you’ll excuse me I’m off to the shop to fiddle with my square, saw and pricker.

— Christopher Schwarz

I keep a short list in my head of what I like to call “The Woodworking Mysteries” – things that I pretend to understand but are really just outside my grasp.

One of the mysteries is how a tree can pump water and nutrients from its deepest roots to the furthest reaches of its branches. We have many clues as to how it works, but a complete picture eludes me at least. Another mystery is about how yellow glue (polyvinyl acetate) actually works. Again, I’ve never read a satisfying explanation.

A third mystery relates to handplanes and basic geometry. One common strategy for reducing tear-out in a board is to skew the plane as you make the cut. This strategy was beaten into my head by all my teachers dead and living. It’s repeated on the Internet by people I deeply respect and trust. And I do it myself in my work.

But if you do the math, you will quickly see how this strategy doesn’t make much sense on its face.

Let’s start with a fact that we do know: The higher the angle of attack when you plane a board, the less likely you are to experience tear-out. This is an almost immutable truth. It’s why we have high-pitch planes and scrapers in our arsenals.

Now for another fact: Skewing a plane in use reduces your angle of attack. Mike Dunbar, the founder of The Windsor Institute and a personal hero, explained this to me in the clearest way possible. When a shaving encounters a plane iron, the angle of attack is like a hill that the shaving has to walk up. If you walk straight up that 45° hill, that’s a lot of work. When you skew the tool, it’s like the shaving is walking up the hill at a lower angle. Or put another way, it’s a bit like building a road up a steep mountain. You don’t make the road go straight up the mountain, you build switchbacks so the vehicles can actually make it up the incline. Skewing reduces the amount of work required – both to plane a board and to climb a hill.

How much does skewing reduce your angle of attack? John Economaki, the founder of Bridge City Tools, published a brilliant chart that explains this on his web site page that promotes his variable-pitch plane. You can see the chart in full here (scroll down to the section titled “Skewing the Plane.”) You can look at this chart and see immediately that skewing a 45°-pitch handplane by 30° will reduce your effective angle of attack to 40.9°.

So here’s the problem: If high planing angles reduce tear-out, and skewing a plane reduces your angle of attack, then how can skewing the plane reduce tear-out?

Here’s a hint: The answer is in the branches.

Planing with no skew resulted in no tear-out on this ash board.

To explore this seeming contradiction, I did a little experiment in the shop on Saturday. I took a short piece of ash with pronounced grain direction – that is, there was no question about which way the grain was traveling in the board.

I cleaned up one face with a smoothing plane and then turned the board around so that I planed against the grain, which is when you are more likely to encounter tear-out. Then I planed the board with a bevel-up block plane, the Lie-Nielsen 102. This plane is bedded at 12° and the iron is sharpened with a 35° micro-bevel, so its angle of attack is 47°. The mouth on the plane is wide open, so it’s not much of a factor. The tool is set to take a shaving that is about .002” thick.

Planing with a 30° skew created this ugly patch of torn grain.

First I planed the board against the grain without skewing the tool. This cleaned up the board just fine with no tear-out. Then I skewed the tool by 30° (which lowered my effective planing angle to about 43°) and did the same operation. I tried skewing both to the left and to the right. Two areas of the board tore out grotesquely.

Then I cleaned up the board again and tried skewing the plane at 20°. Tear-out occurred at the same two places but not as badly. So I tried skewing the plane at a variety of angles. And without fail, the more I skewed the plane, the more tear-out occurred.

So how can skewing reduce tear-out?

You have to remember that trees are not manufactured items. They are giant cones made of fibers that grow in different directions as the tree responds to its environment: a hill, a disease, a wind storm. Then we slice them up into shapes suitable for building things, regardless of how the fibers are traveling through the tree.

In some boards, grain can change directions on you a couple times. And the grain can be at odd angles – you cannot assume that all your boards will have grain running from one end to the other – the grain may be traveling at a 20° direction along the face of the board and 10° along the edge. And the grain might be in the shape of a shallow wave.

So there are times when skewing the plane puts the edge in the right position at the right time to deal with that patch of grain.

Planing at a 20° skew created a little tear-out.

In my example board above, the two places where the tear-out occurred were at places where the grain rose quickly. So how did I deal with this board? As I encountered the areas that tore out, I straightened out the tool – no skew. When I worked the areas that didn’t tear out, I skewed the tool to reduce the effort required for planing.

So the trick with skewing takes us back to the No. 1 way to reduce tear-out: The best strategy is to select the best woods possible and learn how to read the grain so you can begin to predict how your tools will behave. Sometimes, the best strategy is to not skew the tool.

Or put another way: Because grain is irregular, sometimes skewing the plane allows the blade to encounter the grain at a non-skewed angle – and to therefore plane it without tear-out.

This is the end of my series on planing. I hope that some part of it was helpful. Next week, we’ll probably return to the topic of (surprise!) workbenches.

— Christopher Schwarz

If you follow the conventional wisdom for setting your chipbreaker, you will hate your handplane.

What’s the conventional wisdom? According to Charles Holtzapffel’s seminal work on the cutting action of tools, you should set your smooting plane’s chipbreaker .02” from the cutting edge of your iron (other respected sources say to set it even closer than that) and to have an extremely tight mouth. The illustration shown on page 478 of Vol. II of Holtzapffel’s “Construction, Action & Application of Cutting Tools” shows a plane with a mouth as tight as one could imagine.

This, Holtzapffel says, prevents tear-out.

This, says your neighborhood blogger, makes your plane choke like a starving man at the Chicken Bone Buffeteria.

Chipbreakers do more harm than good in a handplane. Whenever I’m having trouble with a plane (especially if the plane is choking or refuses to cut), the first place I look is the chipbreaker. Whenever I fettle a new or vintage handplane and the bugger won’t behave, the first thing I’ll do is swap out its chipbreaker with another plane that has a working chipbreaker. In almost all cases, this solves my problem.

So what is the purpose of the chipbreaker? My cynical view of the gizmo is that it became widely used so toolmakers could use a cheap, thin steel cutter and reinforce it with an inexpensive iron or soft-steel plate. This is supported by the odd names given to chipbreakers. Some early sources call them cap irons, double irons, break irons or top irons. In other words, not everyone agrees that they were designed to break chips.

Early planes had thick irons and didn’t have chipbreakers, even during the age of mahogany, which has irregular grain that tends to tear-out.

In my view, the chipbreaker’s only real purpose in a modern plane is to mate with the tool’s blade-adjustment mechanism and to aid in chip ejection. Oh, and it exists to frustrate you.

You don’t have to take my word for it. Professor Chutaro Kato at Yamagata University did an interesting study of chipbreakers and how their shape and their position on the iron reduces tear-out.

You can read the entire study here. But here’s the quick summary: The chipbreaker actually did its job when it was located .004” from the cutting edge. I have tried to set a chipbreaker on a smoothing plane to this position (using a feeler gauge as a guide), and it doesn’t work well if you have a tight mouth on the tool. My planes just clogged because there wasn’t enough room for the shaving to escape.

If you read Professor Kato’s study carefully, you’ll note that he had better luck with a chipbreaker that had a radical forward-leaning angle – 80°! This 80° breaker worked better even when positioned back a little on the cutting iron. I have yet to try this setup on a plane because the numbers don’t add up. Professor Kato is working with a bevel-down plane bedded at 40°. Do the math: Putting an 80° chipbreaker on an iron bedded at 45° with a tight mouthseems madness. (If anyone has tried this, let me know. I also used to think that $8 for a six pack of beer was madness.)

So in what position should you place your chipbreaker? I set mine back about 3/32” in a smoothing plane in most cases — sometimes even a little further back if the mouth is really tight. All I’m really trying to do is to prevent clogging.

Which begs the question: Why did I list a chipbreaker as one of the ways to reduce tear-out? Well, I did mention one use for the chipbreaker in a modern Bailey-style plane – it mates with the tool’s depth-adjustment mechanism. This mechanism allows you to easily set your tool to take the finest cut possible, which really will reduce tear-out.

— Christopher Schwarz