Guest post on Brian Holcombe's Blog

A nice shot of two of my smoothers, that didn't make it into Brian's blog because of my Stone Age understanding of technology.

Brian Holcombe is one of the most interesting hand tool-based woodworkers I know. He makes fantastic furniture influenced by Japanese furniture, mid-century modernism, and various strands of contemporary studio furniture. What really stands out, apart from his excellent design sensibility, is his meticulous joinery and super-clean hand planed surfaces.

Brian asked me to write a guest post for his blog, and I was very happy to do so. The post is here, and Brian's homepage is here. I highly recommend taking some time to read through the blog--there's a wealth of great information and wonderful photographs. Enjoy!

At Hearne Hardwoods This Weekend

This Friday, 9/30, and Saturday, 10/1, I'll be demonstrating at the Hearne Hardwoods open house in Oxford, PA. There will be a a number of great demonstrators in attendance; In particular, I'm looking forward to seeing Isaac Smith of Blackburn tools. If you are in the area, please come by, say hi, and try some planes. I'll have my usual assortment of smoothers, jacks, and try planes. Hope to see you there!

The Double Iron, Part III

Clockwise from top: Butcher cap iron, early 19th century; Mathieson cap iron, late 19th century; Stanley cap iron, early 20th century, Hock cap iron, late 20th century; Voigt cap iron, 2016.

In parts I and II of this series, I focused on how woodworkers and writers viewed the double iron from the mid-18th century to the mid-20th. Here in Return of the Jedi part III,  I'll look at how this understanding evolved--twice--in more recent times. Let's start with an interesting passage from The Joiner and Cabinetmaker, a fantastic book originally published in 1839, then republished in 2009 by Lost Art Press, with commentary by Joel Moskowitz and considerable new material by Christopher Schwarz. Here is the original text:

In Mahogany…the workman often finds the grain running one way in one part of the board, and the other way in another part, so that he cannot plane both smooth. To remedy this inconvenience, the cabinet-maker's planes are furnished with a double iron; that is, an iron with a flat dull edge is screwed on the face of the cutting iron, so as to prevent the shavings chipping up against the grain. And the more cross-grained the wood is, the closer does the cabinet-maker bring down the dull iron towards the edge of the sharp one, and the finer are his shavings in consequence. The joiner's trying-plane and smoothing-plane, if not his jack also, are likewise furnished with these double irons, to be ready to use with hard and cross-grained woods. But when he is planing straight-grained deal [pine], he keeps the dull iron at a good distance, perhaps an eighth of an inch from the cutting edge…

If you've read parts I and II of this series, you will find the above passage completely unremarkable. Like virtually every other 19th century writer on the subject, our author describes the double iron as the normal remedy against tearout in difficult or reversing grain. The only unusual part of the text is the use of the term "dull iron"; however, recall from part II that Holtzapffel described the cap iron as "moderately sharp," so perhaps it was common to refer to the cap iron as less sharp than the cutting iron.

No, the interesting part is not the original text, but rather the commentary that Joel Moskowitz adds:

 Clark and Williams, the planemakers, have pretty much conclusively shown that the best of the smoothing planes from the late 18th century, a golden age of hand cabinetry, were single irons with a high pitch. Their point is that a fine mouth and a high angle are more important for planing difficult wood than is a double iron. Larry Williams also said that during the 19th century, plane quality deteriorated, and that the double iron at a lower bed angle was adequate for most of the market (joiners), and this squeezed out the dedicated cabinetmaker's tools. Here we see a contemporary reference that suggests otherwise, but the reference cannot be taken at face value (emphases mine). 

The comment that the reference "cannot be taken at face value" is extraordinary, considering that virtually every other period reference makes the exact same claims. But Joel is one of the most knowledgeable experts in hand tool woodworking, and I quote him not to poke fun, but rather to illustrate what had become the common wisdom about the double iron in the late 20th/ early 21st century. At that time, a narrative had emerged, and that narrative was spread and reinforced by teachers, writers, boutique planemakers, and large planemaking companies. In a nutshell, it went like this: Cap irons don't control tearout. They serve only to stiffen the blade, and they were more a convenience to manufacturers than an aid to woodworkers. If you want to plane tearout-free surfaces, you need either a high (above 45°) cutting angle, a tight mouth, or both.

This narrative was extremely influential. In addition to Clark and Williams (now Old Street tool), nearly every other boutique planemaker produced high-angle, tight-mouthed single iron planes. The big planemaking companies began to emphasize bevel-up planes (which can use high cutting angles and don't have cap irons) and high-angle frogs (which allowed users of bevel-down planes to have 50° or 55° degree cutting angles). Woodworking writers extolled the virtues of these newer options, and so common-pitch bevel-down planes like the venerable Stanley/Bailey pattern, or the common double-iron woodie, came to be seen as inferior: suitable for rough work and carpentry, but not fine woodworking. Which is quite ironic: you may remember that back in part II of this series, I quoted David Denning, who wrote in 1891 that while planes "are made with both double and single irons, it should be said that the latter, though cheaper, are not suitable for cabinet working."

At this point, I need to issue a couple of disclaimers. First, I believed this narrative as much as anyone else. I was completely convinced. Hindsight is 20-20 and Monday morning quarterbacks always win, so I can't criticize folks who doubted the double iron without criticizing myself. Second, the proponents of high angles and tight mouths weren't wrong about the effectiveness of those methods: they definitely work. The only error was the claim that double irons don't work.

Today, the narrative I've been describing still has plenty of proponents. But starting around 2012, a counter-narrative began to emerge and gather critical mass. And the counter-narrative was simple: The old guys were right. All those writers from the 18th and 19th centuries were telling the truth: cap irons really do control tearout more effectively than any other method. Cap irons fell out of favor because it's hard to explain in words, or even in photographs, how to set the cap iron close enough to control tearout. It's hard to teach yourself how to use the cap iron. And so there was a collective forgetting of how to use the cap iron.

What changed? The catalyst was in 2012, when Bill Tindall obtained permission to use an English-subtitled version of the Kato/Kawai video, with Mia Iwasaki providing the translation and Wilbur Pan hosted the video on his blog. The video shows, in crystal clear, slow motion, magnified images, the tremendous effect a cap iron can have. The video had actually been available for some time, but having the subtitles made it accessible to a wider audience. Bill publicized the video on the Wood Central hand tool forum, where an older gentleman, Warren Mickley, had insisted for years that double irons were the best remedy against tearout. Two younger woodworkers, David Weaver and Kees van der Heiden, took up Warren's challenge and taught themselves to use the double iron, much as it had been described in all the old references. Kees published two videos, and David published an article, describing the technique in a way that was accessible to modern readers. You can find the videos and article in the links of interest page on my website; they remain some of the best, clearest demonstrations of how to use the cap iron. Later, Kees and Wilbur would publish an article in Popular Woodworking magazine, and better-known woodworkers like Chris Schwarz and Richard Maguire would help knowledge of the cap iron reach a wider audience. Today many woodworkers, probably thousands, have discovered how the double iron can be an incredibly effective remedy against tearout.

And that, in a nutshell, is the story (so far) of the double iron. I'll close by referring back to Holtzapffel, whom I quoted in part II. In 1843, Holtzapffel described the use of the double iron in great detail, but he also discussed how high angles, tight mouths, and even bevel-up mitre planes can all help to mitigate tearout. All these approaches work. I happen to believe that the double iron is, as Peter Nicholson wrote, the "most complete remedy" for dealing with difficult grain, but that, dear reader, is for you to decide.

The Double Iron, Part II

Diagram of a double iron from Turning and Mechanical Manipulation by Charles Holtzapffel (1843)

In Part 1 of this series, I presented evidence that 18th century woodworkers viewed the double iron as a revolutionary technology that was more effective in combating tearout than any other method. An interesting feature of the 18th century writings I quoted is that they give no specifics: No measurements, no angles, nothing. They just describe how the cap iron works in very general terms.


In the 19th century, writers start attempting to describe the operation of the cap iron in more precise terms. The most important of these is surely Turning and Mechanical Manipulation by Charles Holtzapffel (1843). After describing how a narrow mouth opening can reduce tearout, Holtzapffel writes:

The same effects are obtained in a much superior manner in the planes with double irons … the top iron is not intended to cut, but to present a more nearly perpendicular wall for the ascent of the shavings, the top iron more effectually breaks the shavings, and is thence sometimes called the break iron … the top iron has a true edge, which is also moderately sharp … the top iron is placed from one-sixteenth to one-fiftieth of an inch from the edge of the cutter.



Holtzapffel adds two critical facts that were missing in earlier descriptions. First, the cap iron should actually be sharp. Second, the cap iron should present a more nearly perpendicular wall for the ascent of the shavings, so it should make a roughly 45° angle to the blade at the tip; when this is added to the 45° bed angle, we get the 90 degree "perpendicular wall."


So far, so good. But on the crucial question of distance from the cutting edge, Holtzapffel misses the mark. One-fiftieth of an inch, or .020", is off by a factor of two or three. The big payoff with a cap iron, in terms of tearout reduction, happens when it's set .010" or a less from the cutting edge. Anyone following Holtzapffel's instructions to the letter would have to conclude that cap irons weren't very effective. I'll come back to this, but let's continue on…

Many other 19th century writers discuss the double iron, but the range of measurements given is wide. James Lukin, in Our Workshop: Being a Practical Guide to the Amateur in the Art of Carpentry and Joinery (1879), writes:

The break iron of the jack planes is generally fixed, so that its edge…is one-sixteenth behind the edge of the cutter. If the break iron be set back, say one-eighth of an inch, it will not bend the shavings sufficiently, and the planing will very probably be rough. The nearer the edges of the irons are to each other…the smoother will be the work produced, but the labour of driving the plane will be much increased.

As an aside, Lukin also writes that


Planes having single irons are much less laborious to handle, but the work executed by them is neither so smooth nor so truthful as that of the double-ironed description. The shavings escape in long curls or ribands from a single iron, and the surface of the work is left somewhat rough. It is a good plan to remove the first exterior and dirt from a plank with a single-ironed plane, after which the jack and smoothing planes will work pleasantly, and retain their edges for a longer time.

Francis Young, author of Every Man his Own Mechanic (1882) writes:

… when the jack plane is required for heavy work… the edge of the break iron should be about 1/8" from the edge of the cutter, but for finer work it should not be more than 1/20" from the latter; and in the smoothing plane the distance between the edges of the two irons should be less than this, indeed so slight as to be perceptible, but nothing more.

One other 19th century source worth mentioning is The Art and Craft of Cabinetmaking by David Denning (1891). Not so much for his description of the double iron, which is familiar and rather cursory, but rather for his comparison of double vs. single irons:

For coarse, rough work… the mouth may be set comparatively wide, and the edge of the back iron be set one-eighth of an inch from that of the other; while for fine work… the mouth is narrow and the cutting edge only very slightly in advance of the other. In any double iron plane, the nearer the two edges are together the finer will be the shaving, but the labour of planing will be increased. From this it will be seen that the relative positions of the two irons is of considerable importance, and that within certain limits, the planes can be regulated to suit the work on hand. As jack, trying and smoothing planes are made with both double and single irons, it should be said that the latter, though cheaper, are not suitable for cabinet working.

Writers from the first half of the 20th century continue in a similar vein; two excerpts will suffice to illustrate. The prolific author Charles Hayward wrote about the double iron repeatedly throughout his long career; a search of the recently released The Woodworker: The Charles H. Hayward Years turns up more than a dozen explanations of how to set the cap iron. Here's a representative example:

Its [the cap iron's] purpose is to break the shaving as it is raised, and so minimize any tendency of the grain to tear out. The closer to the edge it is set the more effective it becomes, but the greater the resistance it offers. For the jack plane it can be set about 1/16" from the edge; the trying plane (when set fine) about 1/32", the smoothing plane 1/32" or less.

Elsewhere, Hayward gives a diagram showing incorrect (Figure 10) and correct (Figure 11) shapes for the cap iron:

Finally, the book Planecraft, originally published in 1934 by C.W. Hampton, gives the following recommendation:

For rough work, [set the] cap iron 1/32" to 1/16" from edge. For finishing work… 1/64" to 1/16". For hardwoods with irregular grain… as close as you can get it to the cutting edge.

This last excerpt is quite interesting, because it's the only one that accurately conveys how the cap iron should be set: up to 1/64" from the edge for normal circumstances, and (implicitly) closer than 1/64" for hardwoods with difficult grain.

........................

 
So far in this series, I've presented excerpts spanning nearly 200 years. I think we can conclude three things about the authors of these writings: one, they believed that double irons were superior to single irons or any other method of controlling tearout; two, they agreed that the cap iron must be set close to the cutting edge; and three, they were (excluding the author of Planecraft) terrible at conveying just how close the cap iron needed to be set. So why did these guys fail so badly at this task?


I think there are two reasons. First, the earliest writers were not writing the kind of how-to manual for amateurs that modern readers are used to. In the 18th century, nobody learned woodworking from reading a book--the only way to learn the craft was as an apprentice. Nicholson and Salivet were describing, not instructing. it would not have occurred to a craftsman like Peter Nicholson to give a precise description, with exact measurements, of how to set a cap iron. If he had wanted to show someone how, he would have simply demonstrated it.


Later writers like Lukin, Young, and Denning were writing for amateurs, but I think they fell short for a different reason. A clue may be found in the book The Tool Chest of Benjamin Seaton. As Jay Gaynor and Peter Ross explain:


The workmen who made these tools as well as those who used them often shaped or fitted their work by sight or touch … rather than by inches and fractions. Rules were divided only to 1/8". Micrometers were in their earliest stages of development. On a workaday basis, most metal- and woodworkers didn't think in terms of smaller mathematical dimensions. They were unimportant as long as the result looked right and worked well.


In the 19th century, smaller fractional divisions gradually became more common, but divisions above 1/32" or at most 1/64" were rare. Today, we take it for granted that we can buy cheap dial calipers that accurately read in thousandths of an inch; we can roll down to the auto parts store and buy feeler gauges that give us fixed references for any distance between .001" and up, or we can used mass produced goods like paper (.003") or playing cards (.012") to create a frame of reference. But in the 19th century they didn't have cheap calipers, or mass-produced and standardized goods. In short, the authors I've quoted weren't bad at measuring, or describing; they simply lacked the language and frames of reference to accurately convey tiny dimensions in writing.


This point turns out to have very important implications for the use of the double iron. In the apprenticeship culture of the 18th century, where everything was learned by direct demonstration, it was easy to transmit the workings of the double iron from master to apprentice, or father to son. But from the 1880s until today, an ever-increasing number of hand-tool woodworkers have been amateurs learning from books and magazines. And let's face it, it would be extremely difficult to teach yourself the use of the double iron from any of the books I've quoted in this post. As a result, there was a gradual forgetting of the original purpose and function of the double iron, a forgetting that culminated in the misguided notion that the double iron was not only incapable of controlling tearout, but had never been intended to do so. But that is a subject for Part 3.

The Double Iron, Part 1

At the Lie-Nielsen Hand Tool Event in Covington last weekend, I was asked the same question over and over: "Aren't wooden planes normally single-iron planes?"

Well, yes and no.

Among contemporary, custom planemakers, I am the odd man out: I make double-iron planes, and virtually everyone else makes single iron planes. But 200 years ago, it was a different story. Double irons in the late 18th and early 19th centuries were so successful and popular with woodworkers that they drove single irons into relative obscurity.

In the 20th century, there was a gradual forgetting of the original purpose and function of the double iron, and double-iron planes came to be seen as cheap, mass-market planes, not as capable or as suited to fine work as single iron planes with thick irons, steep beds, and narrow mouths.

Fortunately, the early 21st century has seen a rediscovery and revival  of the double iron. Many woodworkers have discovered that with proper use of the double iron, a flea market Stanley or similar plane can perform on par with the finest custom planes, no modifications required.

In the remainder of this post, I'm going to explore the early history of the double iron, a subject many woodworkers are not acquainted with. Later posts will look at how the double iron fell from favor, and its recent resurgence. Buckle up; this is not a quick and easy read.

……………

The earliest documented reference to the double iron is in an advertisment placed in the Pennsylvania Chronicle, March 2-9, 1767, by Samuel Carruthers.

Here's a modern translation of the key sentence: "Also, double-iron planes, of recent construction, far exceeding any toothing planes or scrapers whatsoever, for cross-grained or curly lumber." In effect, Carruthers is claiming in 1767 that the double iron is the best solution for preventing tearout in difficult grain.

It's tempting to dismiss Carruthers's claim; after all, it was an ad! Fortunately, there are more impartial sources. In the Manuel du Tourneur (1792, 25 years after Carruthers), Salivet writes:

Finally, the double iron plane, its invention not very old, and apparently comes from the Germans, is none other than a tool in which two irons are put together back to back, but this double iron is bedded at a regular angle. The bottom iron, being very inclined takes a lot of the wood, like all planes and jointers, but in this mode it would tear out a lot if the shavings were to enter the throat at that angle. The bevel of the top iron, lifts the shaving and forces it from the inclination at which it was started. But the two irons must not be even; the bottom one should be a little bit ahead. The less the difference, the less tearout produced, to the point where one can plane oak branches, even almost green ones; this is the most difficult test that can be done, as nothing planes as badly as “log” wood. 

Salivet's description is important for a couple reasons. First, it describes how the double iron works: the cutting (or "bottom") iron would cause tearout, but the top iron (what we would call the "cap iron" or "chipbreaker") "lifts the shaving and forces it from the inclination at which it was started." In other words, it breaks the shaving at a more severe angle, hence the name "chipbreaker."

Second, Salivet describes the most important part of actually using a chipbreaker: "the less the difference, the less tearout produced." In other words, the smaller the distance between the cutting edge and the chipbreaker edge, the less tearout there will be.

A third source, and the most important one for me, comes from Peter Nicholson's The Mechanic's Companion. Nicholson was an amazing fellow. He came from humble origins and served a traditional apprenticeship as a cabinetmaker, but he later became an accomplished mathematician, architect, author, and teacher, all with virtually no formal training. Like Roubo, he was an intellectual who never forgot his roots as a working tradesman.

  The Mechanic's Companion has a publication date of 1831, but that is misleading. The book is a reprint of Mechanical Exercises, written in 1812, and reflects Nicholson's earlier experience as an apprentice and cabinetmaker. By 1792, he had already moved on from cabinetmaking to writing and teaching, so I am pretty certain the book primarily reflects his experiences in the 1780s, only twenty years or so after the Carruthers advertisment.

Concerning the double iron, Nicholson writes:

To prevent the iron from tearing the wood to cross-grained stuff, a cover is used with a reversed basil, and fastened by means of a screw. 

Remember, "stuff" is wood, and "basil" means bevel, so Nicholson is just saying that a chipbreaker will prevent tearout in wood with cranky grain. He continues:

The basil of the cover must be rounded, and not flat, as that of the iron is. The distance between the cutting edge of the iron, and the edge of the cover, depends altogether on the nature of the stuff. If the stuff is free, the edge of the cover may be set at a considerable distance, because the difficulty of pushing the plane forward becomes greater, as the edge of the cover is nearer the edge of the iron, and the contrary when more remote.

In the first sentence, Nicholson is simply saying that the front of the chipbreaker should be rounded, as in the photo at the top of this post, and not flat, the way a cutting iron's bevel is (and the way many modern "improved" chipbreakers are--a point I'll return to in a future post).

The rest of the passage is the Holy Grail. The distance between the cutting edge of the iron, and the edge of the cover, depends altogether on the nature of the stuff. In other words, the more difficult the grain is, the closer you need to set the chipbreaker to the edge. There's no fixed distance, e.g. .004" or whatever; it depends on the wood. If there is tearout, move the chipbreaker. That's all you need to know.

In the glossary of The Mechanic's Companion, Nicholson adds one more note on the double iron:

The double iron planes now in use, are a most complete remedy against cross-grained and curling stuff; the plane will nearly work as smooth against the grain as with it.

……………

 In the 20th century, it became common to view the chipbreaker as an unnecessary appendage, something that served merely to stiffen the cutter and prevent chatter. What the above sources show is that 18th century woodworkers emphatically did not see it that way. Rather, they saw the chipbreaker as a revolutionary technology that was more effective in combating tearout than any other method. As a result, double iron planes displaced single irons in the late 18th century almost as ruthlessly as the PC displaced the typewriter in the 20th.

In the next post, I'll look at how the understanding of the double iron changed over the 19th and 20th centuries.

Lie-Nielsen Hand Tool Event This Weekend

This weekend, I'll be demonstrating at the Lie Nielsen Hand Tool event in Covington, KY. Chris Schwarz's Lost Art Press will be there, along with many other great toolmakers (Raney Nelson, Conrad Sauer, and Caleb James, to name just a few). If you are coming to the show, stop by, say hi, and make some shavings!

What I've Been Up To

Well, it has been a long time since I've blogged. For anyone who's wondering where I've gone, I have a one-word answer: Instagram. Just as Video Killed the Radio Star, Instagram has been killing blogs right and left.

OK, perhaps I exaggerate just a bit. But there's no doubt that it is a lot easier to snap a quick picture and post it to Instagram with a caption, than it is to write a lengthy blog post. Which is too bad, because there's definitely a place for the longer-form, in-depth treatment that a blog can provide. And after I get past the next couple weeks of craziness, I'll try to crank out some more posts that I've been mulling over.

In the meantime, if you're interested in seeing the stuff I've posted on Instagram, just click on the "view on Instagram" badge in the upper-right corner of this page. Be sure to read the comments for some great conversations with a number of the leading planemakers of today, such as Caleb James, Oliver Sparks, Dan Schwank, Larry Williams, and more.

Meanwhile, here are some snapshots of what I've been up to.

I renovated my drill press:

Then I drove to Indiana and packed the car full of quartersawn beech.

Breakfast there requires two plates!

I made some smoothing planes:

And I'm finishing up some jack planes. Here are 3 mortises I chiseled out in one day. A recipe for sore muscles.

Next week I'm headed to the Lie-Nielsen/Lost Art Press event in Covington, KY. More details soon.