Cap iron setback and shaving thickness

This seems pointless

Patrick Chase

I don't understand why we must insist dogmatically that use of the cap iron was 100% lost to the interwebs, as opposed to 99% lost or 95% lost or whatever.

What is clearly established is that the vast majority of woodworkers, including purported "authorities", were either:

1. Convinced that it was useless for mitigating tearout

2. Using it in a manner that doesn't actually prevent tearout (too much setback).

People seemed to progress from the second category to the first over time, i.e. they would start out misusing the cap iron because they didn't know any better, and then conclude that it didn't work.

My personal opinion is that a lot of people in group (2) think that they "knew about the cap iron all along", and that that's sort of like a homeopath insisting that they "knew about modern medicine all along". With that said I frankly don't see why we must insist on disabusing them of that notion, or how anybody benefits from doing so (other than in a very egocentric sense).

In any case, people like Warren and David deserve a huge amount of credit for re-popularizing the correct use of the cap iron, and that should be enough IMO.

Re: This seems pointless

steve voigt

Ha, pointless is right. I know you are responding to Dave, who has a different point of view, but just to be clear, I never said the knowledge was lost. I gave a specific example of someone who credibly had learned it long ago (Richard Maguire), I wrote that "of course there were craftsmen…who knew about the double iron" and "it's incorrect to argue that the knowledge was ever truly lost." Then someone else tried to twist that into a bogus straw man argument, because straw man arguments are always easier to refute.

David and I might disagree about, as you say, whether it's 90% or 95% or whatever, which is not all that important. But we agree on the main point, which I'll convey with an analogy: If you add up all the people who say they were there at Woodstock in 1969, you could probably populate a decent sized country. If someone says they were there, maybe it's true, but forgive me if I'm skeptical until they show me a ticket.

Re: This seems pointless

steve voigt

I should add, I think your (Patrick's) point about two groups of people, and especially the comparison to homeopathy, is probably right on.

Maguire

Patrick Chase

Richard is actually an interesting example.

Yes, he "knew" about the cap iron, but apparently not enough to make practical use of it in some of the circumstances where it provides the most advantage. Case in point:

http://www.theenglishwoodworker.com/cap-iron-fatigue/

I can't count the number of times I've seen that post cited as a justification for BU jacks/jointers or a reason not to mess with the cap iron on those planes.

The real world is like that: It's not a question of whether the basic knowledge was altogether "lost" (it wasn't) but rather of whether the refinements required for practical exploitation were available to the vast majority of woodworkers (they weren't).

Re: McGuire

david weaver

That is a perfect example. Because the internet often wants TL/DR resolution for us not to have follow up posts, and patrick, you and I are perfect examples because we tend to go all the way to the bud on the farthest branch on the tree before we stop - I didn't say it clear enough about that.

Warren is the only person who gave good advice about it. That's it. "as good as" (fill in the blank, sanding, high angle, etc) doesn't really suggest someone mastered it (go back again then to the person who only uses a plane for surface prep - perhaps to them, all of the options are similar).

That's not to say that someone isn't working in a shop somewhere and doing so without the internet and doing the same thing as Warren. It is just extremely unlikely that there is more than a few of those someones.

I can slice things in a million directions:

"how many people actually working by hand gainfully like warren without supplemental income" (very few)

"how many of those folks aren't using japanese planes and didn't follow nakashima or something similar"

"how often do you see a cap iron on a used plane that looks like it was in use the last time it was put away". I have seen exactly zero, despite buying planes that were actually in use, including infills from luthiers. I was a bit surprised at their level of setup, but maybe they were always scraping by preference. Who knows?

We get down to very few. Warren often talks about "advances" in woodworking draining the skill from the profession to replace it with unskilled labor. I think this is one of those places. It was "advanced" out, even in warren's neck of the woods where he's surrounded by woodworking that's still going.

My thoughts are like Steves - it's not that it was completely lost, I can't believe that would be the case (plus, warren and the two Finns just to start - using it without the internet telling them to). It's just there are lots of woodstock attendees and out of shape lackeys with Navy Seal Tattoos.

Re: This seems pointless

david weaver

We're on the same page, Steve. The woodstock bit is the perfect example. I don't know who started the whole "lost to history" thing (you have to always think in the back of your head that if something works, someone will be using it just by chance, anyway - just not any of the internet gurus).

A whole lot more people know how to use the cap iron because "they read it in planecraft", too, now that it's been beaten to death on the internet.

The Virtue

david weaver

And one of the reasons I'm so insistent on this, though I drone on and on about how much better it is for dimensioning (as are wooden planes for the rough and middle work) isn't really it.

It's the fact that when I started, you sort of got a couple of good planes, and then it was like collecting weapons and armor on diablo after that. You have to level up to handle the next difficult thing. Want to plane curly maple? Buy a high angle plane or a bevel up plane (I tried both). Want to plane something really hard, need "new whiz bang" iron of this or that type so that you can handle it.

I'm not bitter about having spent that money, I'm entertained by trying things. But I often saw comments from people who really didn't want to spend the money there, and the right answer would've been (at the time), you probably don't really need anything else. "A brese plane will work through more difficult material than a stanley". Probably not. A beginner will be able to use it better if they follow a decent paint by number sharpening scheme, but otherwise, both will do about the same thing in a medium hardwood (but the stanley will drop back and do heavier work, too).

The real virtue for every other person who just wants to work wood is that you can have a jack/fore, try/jointer and a smoother and do anything you need to. If the planes have 1970s stanley irons (the softest I've come by), you can still work everything with them.

You can still get (or make) all of those nice tools, but you don't have to.

Re: Maguire

steve voigt

Patrick, I corresponded at some length with Richard about his training and how he learned to use the cap iron. As I mentioned earlier, he was taught by his grandad, who would've learned in the same fashion, direct transmission from master to apprentice. Presumably there were others who learned in the same fashion.

It's true that Richard has a sort of all-or-nothing approach to the cap iron, but that just tells me that he learned it in a very hands-on way, "this is how you do it", and not in an intellectual way, from watching the KK video. It's clear that he knows how to use it effectively.

On the other hand, it's clear that many people who had training didn't learn about the cap iron. Paul Sellers, for example, writes a great deal about his apprenticeship, but it's clear that he's not aware of how the cap iron is supposed to function, doesn't consider it important, doesn't teach it.

The question I've never gotten a good answer to is, what about the (mostly-European) gurus from say the 50s to the 80s who made names for themselves in the U.S? I'm thinking people like Klausz, Frid, Kirby, etc. Did any of them teach the close-set cap iron in their lectures, videos, etc? So far, I've seen no evidence they did, but I don't have enough evidence to say for sure. I know that Krenov didn't, but not sure about the rest.

Answering that question would go a long way towards understanding how widespread the practice was in the mid-20th C. Which isn't going to help anybody's woodworking, but it's interesting purely as a matter of archeology.

Re: This seems pointless

steve voigt

Yes, planecraft or the first issue of FWW.

I read the mostly-accurate description from FWW in about…1995, I think. I promptly tried setting the cap iron super-close. My experience was probably similar to yours…the plane was almost impossible to push; it clogged immediately; shavings jammed between the cap iron and cutting iron. I promptly moved the cap iron back, and didn't really try again until 2012, after you and Kees started writing and making videos about it.

In retrospect, I probably had the following problems: I wasn't a very competent sharpener yet; I hadn't mated the edge of the cap iron to the cutter properly; I hadn't shaped the tip of the cap iron properly--it probably had a steep, blunt edge. I guess that shows what a slow learner I was. But it also shows that it's not the easiest thing to learn on your own.

"Planecraft"

Bill Houghton, Sebastopol, CA

Interesting to see this book mentioned. It was one of my important learning tools, too. In my travels around woodworking forums, I regularly recommend it to new kids. It's now out of print (again), but pretty freely available used, where it commands a price far below its value.

Re: "Planecraft"

david weaver

Bummer that it's out of print again.

Re: Maguire

John Pappas

Steve, Tage Frid did teach about the chipbreaker. From 'Tage Frid Teaches Woodworking' 1979

"The function of the chipbreaker is to prevent the blade from tearing up the surface of the wood. If the chipbreaker is set too far away from the cutting edge of the blade you might as well use the plane without the chipbreaker. For normal use, the chipbreaker shoiuld sit back about 1/32 in. For rough work move it back slightly, for fine work, such as planing curly woods, move it closer to the edge."

Re: Maguire

david weaver

That's quite a nice summary, actually. It's just not specific enough for beginners to take and run with.

But it's quite nice. Charlie Stanford often points out to me that I am focusing on something that is really a fairly small part of the total work product, and maybe Tage Frid thought of it the same way (I know Charlie is a huge Tage Frid fan - he often uses Tage as ammunition in arguments).

I don't know what the gurus did in terms of working wood (if they were power assist and hand tools for finish only). If they weren't working from rough with hand tools only, then the double iron really isn't that big of a deal. Especially if the furniture is modern and sanding is not a big deal.

Re: Maguire

steve voigt

Hi John,

Thanks for the info on Frid, that's very useful. I love that line, if it's set too far away…"you might as well use the plane without."

Double Iron vs. Thick Iron

Tom Colligan

I'll bet a number of us have one or two planes that were made with a thick iron, such as the two I have made by Steve Knight.

Would you offer your take on the benefit of a thick iron, or the lack of one.

That is, does one offer an advantage over the other? Thanks.

Re: Double Iron vs. Thick Iron

david weaver

Just in general (I built "thick iron" single iron planes before I saw Warren's double iron light):

Thick Iron:

Advantages:

* no chatter with long unsupported span (good for planes with wedges that terminate high on the iron or planes with lever caps). A plane of most designs with a 1/8th single iron will chatter. Maybe not in smoothing, but in most other things. The curators at Williamsburg concluded that chatter was just part of planing.

* stable in planes that aren't bedded perfectly - might be an advantage in a plane that moves

* really "solid" feel. they add to the weight of the plane, too - so the "feel" is probably a combination of two things.

* some people really like the aesthetic

Disadvantages (this is for single iron only):

* longer to grind (this eventually becomes annoying when you get used to thin irons)

* no practical way to maintain them only by hand if you want to do that (if we're talking about something like Knight's irons or Brese irons - which are both superb irons, by the way - Steve doesn't get as much press as he should for just how excellent his O1 irons were. They were hard without being brittle like the hocks.

* hard to profile if you want to do that

* tearout control requires high angle or tight mouth (mouth has to be really tight to really be effective - like 2x chip size, which may mean 4 thousandths or so for a smoother). Planes tend to be one-dimensional (e.g., a fine cutting high angle smoother with a very tight mouth or an open mouthed roughing plane)

(when you get the double irons that are a quarter thick and have a cap iron on them, they are solid feeling, but they feel really awkward at the same time - not important I guess)

Thin Double Iron

Advantages:

* quick to grind the iron and the iron can be ground by hand easily if you'd like

* generally cheaper to buy

* easily profiled

* gives a plane a very wide range of working capabilities (fine or coarse with the same plane). I single plane can literally smooth anything once you learn the function of the cap

* adding an adjuster can be done cheaply

* excellent tearout control with a cap iron, as good as anything short of a card scraper and sandpaper. Chatter free in all but the very heaviest cuts (you may still get a tiny bit of it if you set a plane up as a fore and really horse it, but it's the kind of chatter that doesn't matter, and it might actually help make the cut easier. I'd define bad chatter on a heavy cut as the kind that keeps the plane from staying in the cut).

* a bit more forgiveness in plane setup. If the iron is held firmly at the back of the bevel, the top of the cap iron and the top of the iron at a point, it will probably work well and without tearout. The same is true of single irons, but it's a bit harder to hold them close to the point of cut (in terms of plane design)

Disadvantages

* fitting and learning the double iron

* any deep pitting in an iron can be the end of it (hopefully that doesn't occur)

* Not forgiving of major fit problems with a plane, and the plane design still needs to support the cap iron relatively close to the mouth (e.g, where the lever cap meets the hump on a stanley cap iron)

Re: Double Iron vs. Thick Iron

Warren in Lancaster, PA

As David mentioned, a thick iron helps reduce chatter, which is vibration of an iron that is not well bedded. It shows up as regular ridges on the planed surface. A decade ago, people who were unfamiliar with double irons were suggesting that all that a cap iron did was to make a stiffer iron (emulate a thick iron).

What a double iron is good for is tear out, which is quite different from chatter. Tear out occurs when the plane goes over a region where the grain is going in a contrary direction. The fibers are lifted and broken off ahead of the cut reulting in a rough and torn surface. A well adjusted double iron will remedy this problem, leaving a very smooth surface.

Although some suggested that a thick iron would help with tear out also, this does not really happen. Instead, people using single iron planes have depended on other remedies such as high angle of attack, tight mouth, or extremely light shavings. The double iron does not have these restrictions and because the angle can be low, yields a better surface.

Double Iron vs. Thick Iron

Tom Colligan

Thanks, David and Warren.

In reading Warren's third paragraph how important is the pitch of the plane, i.e. 45, 50 or 55 degrees?

That is, if the cap iron is properly set will it perform as well regardless of pitch?

Re: Double Iron vs. Thick Iron

Derek Cohen (in Perth, Australia)

In reading Warren's third paragraph how important is the pitch of the plane, i.e. 45, 50 or 55 degrees?

That is, if the cap iron is properly set will it perform as well regardless of pitch?

Tom, a closed up chipbreaker works regardless of pitch angle. The pitch angle does influence how close it needs to be to the edge of the blade (higher pitch angles are not as critical as low angles).

However the question asked is in danger of missing the point. Especially with the softer woods (in my experience), the advantage of the double iron is that the cutting angle can be kept low, which also favours a thicker shaving. High cutting angles increase the effort to push forward (and progressively so as the blade becomes wider), and consequently these influence how thick a shaving you will take (a thinner shaving is less effort). In hard woods, it is possible to achieve a shiny surface after planing with a high cutting angle. It will just take longer.

Regards from Perth

Derek

Re: Double Iron vs. Thick Iron

David Weaver

Yes, it will work well regardless of pitch. Of the bed angles you provided, 45 is preferable, because it allows a nicer surface on softwood. If you have a high angle plane with a double iron, you can set the cap iron close. 50 degrees still benefits a lot from the cap iron.

Re: Double Iron vs. Thick Iron

Bill Houghton, Sebastopol, CA

A dumb question here. It's been my impression that part of the virtue of a close-set chipbreaker is that it effectively raises the pitch angle, based on the geometry of the nose of the chipbreaker - similar, in that sense to a back bevel on the plane iron, but without the hassle of having to remove a back bevel later.

Is that correct, or am I misunderstanding the situation?

Re: Double Iron vs. Thick Iron

Warren in Lancaster, PA

The idea that a cap iron is in some way equivalent to a high angle plane is not right. The high angle plane is still cutting at a high angle, but the double iron plane is actually cutting at the low angle which is why the surface is better. The lower angle cutting is less abusive to the edge of the iron as well.

The lower the cutting angle, the better, but there are a few more considerations. The cutting angle is the sum of the bevel angle and the clearance angle. The clearance angle has to be 8 or 10 degrees or the plane does not cut very well. And the iron has to be somewhere in the neighborhood of 30 degrees for strength or easy cutting. A plane will work nicely at 40 degrees or a little less, but there is no cushion for error. A 45 degree plane allows for a 30 degree bevel, a 10 degree clearance, and 5 degrees of cushion. If you have a 33 degree honing angle on the iron, there is still a bit of cushion.

Re: Double Iron vs. Thick Iron

steve voigt

Bill, I don't disagree with what Warren just wrote, but let me put it a little differently. In a loose sense, you are right. The double iron, like a very steep angle plane, turns the shaving at at a steeper angle than say a common pitch single iron plane. The difference though, is that with the double iron it's a two-step process: the shaving is first cut at a lower angle, and then almost immediately turned at a steeper angle, which deprives the shaving of the ability to split ahead of the cut and cause tearout. In that sense it's the best of both worlds. Maybe there are no free lunches, but the double iron is as close to a free lunch as you can get.

Re: Double Iron vs. Thick Iron

Bridger

The "cost" of double irons over single irons is complexity. Chipbreaker involve additional maintenance, setup and skill.

Re: Double Iron vs. Thick Iron

Patrick Chase

Another way of wording the same point that Warren and Steve just made:

Surface "glassiness" and effort are largely determined by the cutting angle at the point of contact. The finest surfaces (particularly in softwoods) and lowest planing forces are attained with low angles.

In contrast, tearout can be prevented by an increased angle slightly behind the point of contact.

The intuition behind the cap iron is that you can exploit this difference by creating an edge that starts out with a low angle at the point of contact, and then immediately steepens to prevent tearout.

A double iron isn't the only way we can create such an edge profile by the way - The hook on a properly prepared scraper serves a similar purpose.