CS about capirons

[Kees Heiden]

CS:
In addition to my lecture on nails, I’m also giving a talk on “double irons” – aka “cap irons,” “back irons” or “chipbreakers.”
While a few people on the forums have burned this topic in effigy, I have found that a reasoned, historical-based discussing of this 18th-century device helps students immensely. Most woodworkers don’t have the patience to wade into the nasty discussions about double irons to extract the useful bits.
This lecture is about the useful bits. (And why Stanley needs to spanked for almost ruining the technology for us.)

He's not talking about us, is he?
I wonder what Stanley did wrong according to our friend Chris.

[Derek Cohen]

Kees, I think what Stanley did was to refer only to the chip breaker as a "cap iron", that is, to beef up a thin blade. That is the substance of their patent, as I recall. No where am I aware that they actually proposed that the cap iron be used to bend chips/shavings and be an integral part of chip formation. This was left to others to do. Any other thoughts?

Regards from Perth

Derek

[Kees Heiden]

Yes maybe that's it. But how could that be wrong? How to use the capiron wasn't patentable, it was old knowledge by then. So maybe they assumed everyone knew allready how to use it? Most users were professionals back then who had had some kind of education or apprenticeship. Real user manuals like we have today were not the norm back then.

Stanley Australia published a leaflet in the 1950's with some information about how to use the capiron close to the edge. It's on the toolemera website: http://www.toolemera.com/pampdf/stanleyhintsplaneAU.pdf

[Warren Mickley]

Seven years ago Chris Schwarz thought he knew all about double iron planes also. Here is what he had to say about Kato and Holtzapffel. He interpreted Kato for those who did not have the patience to wade through the nasty paper.

http://blog.lostartpress.com/2007/12...duce-tear-out/

Three weeks earlier I had written this on another forum:

I think highly of the 18th century cabinetmakers and tool makers (many were both, making their own planes). It is somewhat hurtful to hear them disparaged as duped by a marketing gimmick.
My feeling is that anyone who does not see the value of the double iron system probably does not understand how to use it. I know that this puts some people who consider themselves experts into a somewhat lesser category and I apologize for it.


Schwarz certainly did his part to muddy the waters. I wonder if is not still in the dark.

[David Weaver]

Phew, that's not one of the old woodcentral threads where I was beating the drum about the ease of using a single iron plane.

(I noticed larry suggested there is no way to make a double iron plane that doesn't clog at the end of the abutments without terminating them far up the plane. I think we covered that in a few threads here. It does require some careful fitting, but so does everything on a wooden plane in general)

[george wilson]

WHY would someone waste time making 2 parts to a blade when they'd be better off just making the single blade THICKER? The cap iron being only to strengthen the blade makes no sense at all. The cap iron is more trouble to make than the blade: You have to make a die to bend the chip breaker curve into the same shape. You have to make the screw. Very often,you will see that old makers forged a thicker boss on the cap iron where the screw went through,to make more thread length. Else,they made a brass boss that was peened into the cap iron to provide more screw length for the cap screw. All that is MORE TROUBLE AND EXPENSE for the plane maker. And,what for???? To only make the blade stiffer???? That makes no sense at all. There had to be a better reason. And now,it has been shown that the chip breaker keeps difficult wood from tearing IF you know how to USE it. I see no need for discussion beyond that simple fact.

I do not mean to sound sour here,just re reciting the facts about manufacturing costs and facts proven by the Japanese video,and actual users.

[Kees Heiden]

Back then in 2007 Chris ran into the same trap as I did at first. When you set the capiron closer to the edge AND you have a tight mouth, you run the chance of clogging the mouth. It takes some precision work on preparing the capiron to make that combination possible.

One thing, he wasn't afraid to eat crow when he discovered that he had been wrong.

[Sean Hughto]

I think there is a typo in the title of this thread: The correct first letter is two spaces right on the keyboard. Natural finger slip. ;-)

[george wilson]

I also did not know the correct use of the cap iron,and was glad to find out. I never would have gone so far as to say that the cap iron was put there JUST to FRUSTRATE you,though. I THINK I read that in the link above. But,I'm getting old and forgetful.

Edit: I DID read that after all!! Why would penny pinching manufacturers make extra parts just to FRUSTRATE their customers??????? That kind of of bass ackwards to business wisdom,isn't it?

I'm not knocking Chris here. I'm quoting him. Do not accuse me of "piling on".

[Adam Cruea]

My understanding is that a high angle of attack on the chips reduces/removes tear out more than a closed mouth; is this the correct understanding?

[Steve Voigt]

One thing, he wasn't afraid to eat crow when he discovered that he had been wrong.

That's right:
http://www.popularwoodworking.com/wo...t-totally-evil

I have much respect for Chris, George, and anyone else who is not too proud to admit they didn't really know how to use the double iron. No respect at all for the ones who say "oh, I knew that all along" because I'm sure almost all of them are lying.

I have no idea what he's talking about re Stanley, though.

And with that, I think I might just be done talking about double irons. George is right; there's not much to say that hasn't already been said about this.

[Jim Koepke]

... what Stanley did was to refer only to the chip breaker as a "cap iron", that is, to beef up a thin blade. That is the substance of their patent...

Regards from Perth

Derek

With a little digging (via Google) this was found:

The 18th century brought significant improvements to the wood plane. Handles began to evolve which made the plane much easier to use. The installation process of the iron evolved as well. The iron was wedged into place in tapered grooves which were cut into the sides of the body rather than being wedged against a cross-bar. Wedging the iron in tapered grooves with a more thinly shaped wedge allowed the plane to clog less often, and hence, increasing the work time. Much later in the century another improvement was made to the plane’s design, the use of double iron. A slightly curved cap iron, or chipbreaker, screwed to the cutting iron greatly improved the plane’s ability to cut difficult wood. This made the entire plane heavier, more rigid and more stable, and it allowed the shavings to curl and break apart as they pass through the mouth. This simple mechanical advantage reduced tear out and left smoother surfaces.

Could it have been that Leonard Bailey (Stanley Rule & Level) couldn't patent something already part of common practice and in wide use? In the design of things Bailey/Stanley, the cap iron is what connected the blade to the Bailey adjuster.

Did other cap irons of the day have the pronounced hump of the Bailey design?

This hump allowed the Bailey designed lever cap a 'springy' surface with which it could perform its purpose.

It appears others may have already knew about the advantages of using a double iron to impart better control of shavings in turn causing a better surface may not have been a patentable feature.

At that time many skilled workers were reluctant to divulge the 'secrets' of their trade. If some young wiper snapper came along with all of their knowledge they might be out of a job.

In my lifetime I have worked with people who felt as much.

jtk

[Jim Koepke]

My understanding is that a high angle of attack on the chips reduces/removes tear out more than a closed mouth; is this the correct understanding?

Not sure if you are talking about a high angle bedding of the blade or the angle of the meeting of the shaving against the chip breaker.

From my experience since this has all been made clear, setting of the cap iron has more effect on reducing tear out than setting the mouth tight.

Of course as always,

YMMV!!!.jpg

jtk

[David Weaver]

My understanding is that a high angle of attack on the chips reduces/removes tear out more than a closed mouth; is this the correct understanding?

IME, the high angle is generally more helpful than closing the mouth if elimination of the tearout is what you want. Closing a planes mouth with a thick shaving will often leave a tolerable amount of tearout prior to final smoothing, but raising the angle will often eliminate it. There are levels of severity with each, I'm sure, where just closing a mouth to a tiny amount will do the job, but I've always had a distaste for how that:
1) limits the shaving a plane can take - you're often at such a narrow feed that any shaving you could feed through wouldn't tear out much to begin with
2) feeding any shaving through the plane that has a thickness that's a substantial % of the mouth width is akin to breathing during a mild asthma attack. You can do it but it just doesn't feel right.

[Derek Cohen]

My understanding is that a high angle of attack on the chips reduces/removes tear out more than a closed mouth; is this the correct understanding?

Hi Adam

The size of the mouth becomes unimportant once you have a cutting angle of about 55 degrees. Leave it wide open if you like with a 60 degree bed in a BD plane or a 60 degree included angle in a BU plane.

Regards from Perth

Derek