chipbreakers?

[Gordon Harner]

As one of the old goats, I was fortunate? to participate in my junior and senior high school's woodshop programs. The training was at best rudimentary. My understanding on chipbreakers is that the primary reason that they were added to plane irons was to reduce the chatter that was more common with thinner irons. I also am aware that they also "break" the shaving as it exits the mouth. My question concerns the placement of the chipbreaker at the edge of the iron. What is everyone's thoughts on chipbreaker placement and why? Does it much matter

[David Myers]

Prepare for a deluge of information, Gordon.

Short answer, gleaned from others here and elsewhere:
For smoothing, the chipbreaker is extremely important in controlling tearout. For this operation, it should be placed as close to the leading edge of the blade as you can and still get shavings without clogging the mouth of the plane.

[David Bassett]

... I also am aware that they also "break" the shaving as it exits the mouth. My question concerns the placement of the chipbreaker at the edge of the iron. What is everyone's thoughts on chipbreaker placement and why? Does it much matter

This is a topic with a lot of passion and you will get conflicting opinions. My best attempt to reconcile the different strongly held beliefs is that the usefulness depends primarily on the characteristics of the wood you commonly use and secondarily on your skill in setting the chip breaker. With straight grain easy to plane wood, you will get minimal benefit (and likely not develop the skill to benefit.) With more "interesting" grain, or in situations where you are forced to plane against the grain, a skillfully set chip breaker will prevent tearout (at the expense of other things, typically more effort.) Also, other factors affect how much tearout you get in any situation, e.g. higher cutting angle, and might be enough to control tearout in your situation with less skill.

Don William's blog'd about learning to set the chip breaker last year: Lesson From A Maestro

Also, to learn to set a chipbreak David Weaver (a former member here) wrote an article about the technique many have cited as useful, "Setting a Cap Iron". (It shows up in Google.)

[Warren Mickley]

I have used the double iron to control tear out since 1973. I learned about the technique from 18th and 19th century sources because, at that time, the craft was in a sort of dark age and I did not read contemporary material. I was quite shocked when I later found that many thought it did not work.

You can learn to place the cap iron by experience. Placement depends on the thickness of your shavings and the nature of the material. If you are having trouble with tear out, the cap iron is too far back. If the cap iron is too close, the plane will be hard to push and the surface will be kind of scuffed up the way it looks from a high angle plane.

As I read in 1973:

"Double iron'd planes ... far exceeding any tooth planes or uprights whatsoever for cross-grained or curled stuff" Carruthers 1767

"best general remedy for curling or cross-grained stuff" James Smith 1816

[Kees Heiden]

For smoothing, but also for jointers and tryplanes, the chipbreaker is vital to prevent tearout in a bevel down plane.

To sum it up in a few words:
When you still get tearout, the chipbreaker should be set closer to the edge (and it had to be set a whole lot closer then I thought possible at first!). If you don't get tearout on some reversing grain, but the going is rough, a lot of resistance and shavings don't look nice and straight, you might have set it too close and some experimenting is in order.

Some problems you might encounter:

Clogging. Don't try to mix a tight mouth with a close set capiron. Of course, everything is possible with due care, but this is a recipe for frustration.

Clogging. Shavings find their way under the capiron. It really should be mated to the back of the cutting iron as perfectly as possible. When holding the assembly up to a light source and peeking in between, no light should be visible between the two.

Resistance. You might have an edge on the front of the capiron that is too steep. A gradual curve, terminating in an angle about 50 degrees steep like an old Stanley capiron, is about perfect.

[david charlesworth]

Try googling Kawai & Kato chipbreaker/capiron research. you should find some interesting video of some of their experiments.

David C

[Dave Clarke]

Here's a video of the action:
https://vimeo.com/158558759

[Bruce Haugen]

Here’s a really good start on the subject.

[bill tindall]

From the "horses mouth" on this topic, namely Kato and Kawai who wrote a tutorial on the topic of setting the cap iron for their trade school students...all what Warren said plus when it is set too close the shaving will compress along its length which can be described as "accordion" as in folded like an accordion bellows. You will recognize it immediately if you get it. Go find the video, but, the video was made to demonstrate the planing machine to attendees at a technical wood machining conference, NOT, to teach the best settings.

[Nicolas Adie]

Richard Maguire did a reasonably short video explaining this very issue

https://www.theenglishwoodworker.com...breaker-video/

[glenn bradley]

And so it was that Pandora's Box was once again opened. 'chipbreaker site:www.sawmillcreek.org' will yield much info.

[Alan Schwabacher]

Keep in mind that while placing the chipbreaker close to the edge will control tearout in wild grained wood, with well-behaved stock planed in the right direction, you don't need it close. Make sure you can sharpen, and plane easier stuff first, then when you run into difficulties move the chipbreaker closer to the edge and look and feel for differences as you plane.

[bill tindall]

You speculation of how the mis-named chip breaker works is incorrect. It works to control tear-out the same way a close set mouth works, namely by restricting the flow of the shaving, which in turn applies a force along the length of the shaving. This force pushes down on the wood ahead of the blade tip and resists it lifting and splitting ahead of the blade tip. One can see the result of this force when the chip breaker is set too fine. The shaving collapses into an accordion.

[steven c newman]

Wasn't there a large thread a few years ago...by David Weaver, about this very subject? Got rather heated, too....

Should I salt or butter the popcorn?

[Jim Koepke]

Should I salt or butter the popcorn?

No, salt raises the blood pressure and the butter clogs the arteries. Us old farts don'g need that.

jtk