setting japanese plane chipbreaker

[Kevin Neff]

I read that you can set the chipbreaker by tapping it in until the shaving curls backward instead of forward. Well, until the shaving doesn't really curl at all---it just shoots out of the mouth over the blade instead of forming a curl in the throat.

I tried it out and it seemed to work. It may depend somewhat on the thickness of the shaving. I think thicker shavings are more likely to be straight.

Has anyone else heard of or experienced this? Does anyone know the proper way to set the chipbreaker?

[Robert Hazelwood]

If the shavings are being straightened then the breaker is doing its job. And yes, it's true that thicker shavings will straighten more readily- the ideal chipbreaker setting varies with shaving thickness, and a thin shaving needs a closer set to have the same effect.

Take some shavings against the grain or on some figured wood and see what happens. Then back out the chipbreaker, take more shavings and compare. You should be bale to see a clear improvement from the chipbreaker.

[Stanley Covington]

I read that you can set the chipbreaker by tapping it in until the shaving curls backward instead of forward. Well, until the shaving doesn't really curl at all---it just shoots out of the mouth over the blade instead of forming a curl in the throat.

I tried it out and it seemed to work. It may depend somewhat on the thickness of the shaving. I think thicker shavings are more likely to be straight.

Has anyone else heard of or experienced this? Does anyone know the proper way to set the chipbreaker?

The best setting for a chipbreaker is to remove the chipbreaker (aka sub-blade) entirely.

The only benefit of a chipbreaker is to prevent tearout. Other than preventing tearout, it does not improve the wood being planed, nor does it make the finished surface smoother or shinier. In fact, the chipbreaker significantly increases the effort required to make the blade to cut. If the grain of the wood is well-behaved, you can remove the chipbreaker entirely. We don't always get to use such pleasant wood, though, so the chipbreaker helps.

Therefore, the most effective setting for the chipbreaker will depend on the wood being planed, the approach of the cut, and the plane being used at any point in time. To use trial and error, add to your experience, and improve your intuition are the only useful pointers anyone can give you.

As to the plane itself, make sure the chipbreaker and blade are perfectly mated (no gap, no rocking). Make sure the chipbreaker is properly sharpened, both ura and bevel, and that the bevel is smooth. The bevel does not need to be as smooth or shiny as a mirror, as a high polish will actually increase friction.

When setting the chipbreaker, make sure it is the same distance from the cutting edge over its entire width.

Learn how to see the gap between the chipbreaker and cutting edge. Not always easy to do.

Stan

[Patrick Chase]

I read that you can set the chipbreaker by tapping it in until the shaving curls backward instead of forward. Well, until the shaving doesn't really curl at all---it just shoots out of the mouth over the blade instead of forming a curl in the throat.

If it's shooting straight out then you've achieved what's called a "type II shaving", and that means that the chipbreaker is set sufficiently close to prevent tearout. This page (http://planetuning.infillplane.com/html/shaving_formation.html) (by Steve Elliott, who posts here or at least used to) gives a good concise overview of the chip types.

Note what Stanley said, however - if you set the CB super-close when you don't need to then you're just making additional work for yourself and possibly degrading the surface quality a tiny bit.



I tried it out and it seemed to work. It may depend somewhat on the thickness of the shaving. I think thicker shavings are more likely to be straight.
Yep, the ideal chipbreaker position depends on the shaving thickness. A cap iron that's close enough to produce a type-II shaving at 4 mil thickness might not do so at 1 mil (though you might not care since tearout is less likely to begin with at 1 mil). That same setting might also cause unacceptable clogging if you tried to take an 8 mil shaving with it.

EDIT: I can't link to it as it's on a competing forum, but you'll find a useful article if you search for "david weaver setting a cap iron". Also this video (https://www.youtube.com/watch?v=9pAVgfSPMN0) on Youtube.

[Kevin Neff]

Thanks for the link.

This reminds me of a photo in Understanding Wood (Hoadley) in the vaneer section. To avoid breaking the vaneer, pressure is applied via a pressure bar (aka nose bar). In the plane, it's the leading edge of the mouth. Here's a photo:

https://www.researchgate.net/profile/Robert_Mcgavin/publication/282471233/figure/fig3/AS:297277135573022@1447887801002/Fig-4-Cutting-force-reference-system-for-roller-pressure-bar-P-is-the-knife-gap-and-C.png

I guess it's a little different because we're dealing with thin shavings and knife checking isn't the concern. I think it's interesting to see the parallels between different types of equipment.

[Patrick Chase]

Thanks for the link.

This reminds me of a photo in Understanding Wood (Hoadley) in the vaneer section. To avoid breaking the vaneer, pressure is applied via a pressure bar (aka nose bar). In the plane, it's the leading edge of the mouth.

Yes, the nose bar is analogous to a tightly set mouth. There are plane designs (single-iron infills and bevel-ups for example) that rely on that approach to limit tearout. It's pretty much an either/or thing though - combining a tight mouth with a close-set chipbreaker is a recipe for jamming.

If you have the Hoadley book then he covers the shaving types in more depth than the article I linked on pp. 161-165 (2nd edition). There's also a good treatment on pp. 229-234 of Leonard Lee's sharpening book. I have to admit that (probably like a lot of people) I'd read both of those more than once before 2012 and yet somehow didn't internalize that they were in conflict with all of the sources saying that cap irons were just blade stiffeners etc. Sometimes we really need to be smacked upside the head to get clued in.

[Pat Barry]

I'm most interested to see Brian's comments on this topic. Many of the comments are counter-intuitive or maybe just wrong. If the OP is getting straight shavings then things must be OK, right?

[Stanley Covington]

Please re-read the OP's original post.

A functioning chipbreaker always causes the shavings to curl because its function is to compresses and bend the shavings the instant they are cut. If the shavings are coming straight out, without any curl, the shavings are not impacting the chipbreaker with significant pressure. This is clear evidence that the chipbreaker is not functioning. If there is no tearout, this is a fine thing indeed.

In the videos of the kezuroukai you will see shavings coming straight out of plane's opening without backward or forward curling. These planes do not have a chipbreaker. The wood is extremely well-behaved, if we translate the Japanese term directly.

This can be accomplished by simply removing the chipbreaker. Try it on some straight-grained softwood.

But a better solution is to use a single-blade plane with a special mouth. Single-blade planes are simple and elegant tools, but are difficult to make. Make one, use it, and then talk about counter-intuitive.

[Stewie Simpson]

Stanley; you may find this video of some interest;
https://www.youtube.com/watch?v=c0N5pV8N1H0&feature=youtu.be&t=373

If you want to view the video's full content, you will need to reset the video timer back to 0 min.

Stewie;

[Warren Mickley]

I read that you can set the chipbreaker by tapping it in until the shaving curls backward instead of forward. Well, until the shaving doesn't really curl at all---it just shoots out of the mouth over the blade instead of forming a curl in the throat.

I tried it out and it seemed to work. It may depend somewhat on the thickness of the shaving. I think thicker shavings are more likely to be straight.

Has anyone else heard of or experienced this? Does anyone know the proper way to set the chipbreaker?

I have used the double iron to plane fine surfaces for over forty years. In 2011 I convinced David Weaver to take the trouble to learn to use it.

The use of the double iron is an art. The best way to evaluate its effectiveness is by judging the quality of the surface left behind, and to develop a feeling for what will happen if the cap iron is moved. The placement of the cap iron depends on the nature of the timber and the thickness of the shaving. Looking at the shavings can be helpful in a gross evaluation.

If a car backfires, that might indicate it needs a tune up, but the absence of backfire does not insure that adjustments are optimum. Likewise just because someone can operate a manual transmission without stalling does not mean they are operating the car in an artful or optimum way.

If you follow some rule-of-thumb, you might stay out of trouble, but fine surfaces may elude you.

[Brian Holcombe]

Pat, I don't see any comments that I would disagree with. I agree with Patrick, Stan, Warren, and Robert. The surface is not improved unless there is a risk of tearout. If I can plane well without a tight set chip breaker I will do so, for reasons Stan mentioned and becuase it wears the edge more rapidly. So use the appropriate setting at the appropriate time. When I started setting chip breakers I began by setting to 'kill' in every instance, I've backed off considerably from this approach to reading the wood and adjusting accordingly.

[Patrick Chase]

Stanley; you may find this video of some interest;
https://www.youtube.com/watch?v=c0N5pV8N1H0&feature=youtu.be&t=373

If you want to view the video's full content, you will need to reset the video timer back to 0 min.

Stewie;

Wow, it's like Kato/Kawai but from the 1930s and in German. There is nothing new under the Sun.

Nice find! The money shot of a close-set cap iron making straight shavings is at 4:59 (https://www.youtube.com/watch?v=c0N5pV8N1H0&feature=youtu.be&t=299). Immediately before that is a close-set cap iron causing jamming in conjunction with a tight mouth, and after is a loosely-set cap iron not doing much of anything. The first part of the video demonstrates the "nose bar approach" with a very tight mouth.

[Pat Barry]

Please re-read the OP's original post.

A functioning chipbreaker always causes the shavings to curl because its function is to compresses and bend the shavings the instant they are cut. If the shavings are coming straight out, without any curl, the shavings are not impacting the chipbreaker with significant pressure. This is clear evidence that the chipbreaker is not functioning. If there is no tearout, this is a fine thing indeed.

In the videos of the kezuroukai you will see shavings coming straight out of plane's opening without backward or forward curling. These planes do not have a chipbreaker. The wood is extremely well-behaved, if we translate the Japanese term directly.

This can be accomplished by simply removing the chipbreaker. Try it on some straight-grained softwood.

But a better solution is to use a single-blade plane with a special mouth. Single-blade planes are simple and elegant tools, but are difficult to make. Make one, use it, and then talk about counter-intuitive.

What is intuitive, to me at least is exactly this
"A functioning chipbreaker always causes the shavings to curl because its function is to compresses and bend the shavings the instant they are cut".
What is counter-intuitive is this
"If the shavings are being straightened then the breaker is doing its job"
and this
"If it's shooting straight out then you've achieved what's called a "type II shaving", and that means that the chipbreaker is set sufficiently close to prevent tearout.".
What seems wrong is this
"you can set the chipbreaker by tapping it in until the shaving curls backward instead of forward."

I'd also like to better understand this statement "If I can plane well without a tight set chip breaker I will do so ... because it wears the edge more rapidly." I feel this is also counter -intuitive. I'm not seeing why a tight set chip breaker affects edge retention.

Finally, I'd be curious to know what Warren really gets for shavings when he has need for a close set chipbreaker. Are they tightly curled or are they 'shooting' straight out of the plane?

[Patrick Chase]

What is intuitive, to me at least is exactly this
"A functioning chipbreaker always causes the shavings to curl because its function is to compresses and bend the shavings the instant they are cut".
What is counter-intuitive is this
"If the shavings are being straightened then the breaker is doing its job"
and this
"If it's shooting straight out then you've achieved what's called a "type II shaving", and that means that the chipbreaker is set sufficiently close to prevent tearout.".
What seems wrong is this
"you can set the chipbreaker by tapping it in until the shaving curls backward instead of forward."

There's some dependence on the wood and shaving thickness here, so no single statement will be accurate in all cases. As Warren says surface quality is the ultimate judge. Everything else is just a rule of thumb.

With that said, the intuition behind straight shavings is that the cap-iron breaks the fibers in the shaving at very frequent intervals and thereby reduces the shaving's stiffness. If the shaving would have tended to curl without the cap iron (and many do) then it will do so less strongly or not at all once "broken". You can see this pretty clearly by examining shavings under high magnification.

The video Stewie posted actually demonstrates this pretty well. You can see a loose-set chipbreaker producing a curl-prone shaving here (https://www.youtube.com/watch?v=c0N5pV8N1H0&feature=youtu.be&t=374), and a tighter-set one producing relatively straight shavings here (https://www.youtube.com/watch?v=c0N5pV8N1H0&feature=youtu.be&t=299). Conversely, the Kato/Kawai video (which used a softwood IIRC) showed curly shavings in all configurations.

[Brian Holcombe]

Pat,

A functioning chip breaker is working the chip back against itself and using the blade as its backdrop to do this. The effect is more wear. When I need the chip breaker action of course this is the best of all worlds, but I certainly notice myself sharpening more often than I do when I have a more relaxed setting. More reason to set as required than to search for a one size fits all solution.

[Patrick Chase]

Pat,

A functioning chip breaker is working the chip back against itself and using the blade as its backdrop to do this. The effect is more wear. When I need the chip breaker action of course this is the best of all worlds, but I certainly notice myself sharpening more often than I do when I have a more relaxed setting. More reason to set as required than to search for a one size fits all solution.

A simpler way to look at this is to ignore the exact chip formation mechanics and simply look at planing forces. As a few people have noted in this thread, tightening the cap-iron set increases planing effort/force. That increased force must be acting at or just above the point of the cut (since the rest of the plane<->wood interface hasn't changed), and will logically produce increased blade wear.

Brian's mechanical explanation makes sense, though I'm not 100% convinced that's the only thing at play. Wood is a complex material, and we're talking about stuff that occurs on relatively small scales.

EDIT: Steve Elliott has posted pictures from the Kato/Kawai study here (http://planetuning.infillplane.com/html/review_of_cap_iron_study.html), showing wear on the back of the blade just above the cutting edge, where the shaving turns as Brian describes, so I think it's safe to say that that wear mode is indeed a contributor :-)

[Kevin Neff]

Now that I'm re-reading that section, he says it depends on temperature and moisture content, too. And speed, I suppose. So maybe Stan is right to recommend trial and error. It may actually be easier than the theory.

I do not enjoy dealing with the additional blade. Now, I have reason to leave it out :)

[Patrick Chase]

Now that I'm re-reading that section, he says it depends on temperature and moisture content, too. And speed, I suppose. So maybe Stan is right to recommend trial and error. It may actually be easier than the theory.

My take: The theory is helpful to understand why we should learn to use double irons. It's also helpful to know when diagnosing problems, for example it's useful to be able to look at the shaving, figure out what "type" it is (keeping in mind that cutting mechanics can and do change within a shaving :-), and understand what factors go into determining that.

Theory isn't terribly helpful to understand how to approach a specific workpiece. Warren and Stanley are right on about that. You can stare at books and videos all you want, but wood is an incredibly complex medium that often defies analysis. As an engineer I can predict how common engineering materials will behave with reasonable accuracy, but planing wood is beyond me in that respect.

Empiricism is your friend, and the theory is mostly useful as a tool to help understand what the empirical results are telling you.

[Warren Mickley]

Pat Barry asked about the shavings from my planes. I used a smoothing plane on some sapele with very strong ribbon figure (interlocked grain); the shavings are limp. Savings from my trying plane are likely to be flat sheets, shavings from by jack plane are not. I think shaving thickness plays a roll here.

I think that if the double iron caused noticeable increase in force required, the cap iron is likely too close. As Brian noted, you really want to be on the risky side when placing the cap iron rather than the safe side.

I wrote this on another forum in 2007:
the double iron is a sophisticated instrument. For things to work well everything has to be just so. There is no shame in having trouble with it. If the idea of learning to use hot hide glue turns you off, the double iron is not for you. It takes a fair amount of practice to get a good feel for it. I can say that the benefits of learning are well worth the effort and I would not want to be without it.

When you are six years old it seems like a lot of effort to make the jump from tricycle to bicycle.

[Pat Barry]

A simpler way to look at this is to ignore the exact chip formation mechanics and simply look at planing forces. As a few people have noted in this thread, tightening the cap-iron set increases planing effort/force. That increased force must be acting at or just above the point of the cut (since the rest of the plane<->wood interface hasn't changed), and will logically produce increased blade wear.

Brian's mechanical explanation makes sense, though I'm not 100% convinced that's the only thing at play. Wood is a complex material, and we're talking about stuff that occurs on relatively small scales.

EDIT: Steve Elliott has posted pictures from the Kato/Kawai study here (http://planetuning.infillplane.com/html/review_of_cap_iron_study.html), showing wear on the back of the blade just above the cutting edge, where the shaving turns as Brian describes, so I think it's safe to say that that wear mode is indeed a contributor :-)
Looking again at the video, its pretty clear that 1) shavings want to curl naturally. 2) the chipbreaker strengthens this tendency of the shavings to curl. 3) The wear (judging from the video) is probably no significant difference at the edge with or without the chipbreaker. 4) The wear on the bevel is a function of the depth of the shaving and the chip breaker may in fact help reduce this wear due to the physics, but this is probably only true if the chip breaker angle + the blade angle are > 90. 5) If the chip breaker + the blade angle are less than 90, then the wear on the bevel is probably not all that much affected.

Interestingly enough, I didn't see any straight shavings in the video but that may just be more a function of the grain direction and the blade angle.

Even in the paper cited, I didn't see strong correlation between degree of wear with or without the chipbreaker.

Anyway, that is what I see looking at the video.

[Patrick Chase]

Looking again at the video, its pretty clear that 1) shavings want to curl naturally. 2) the chipbreaker strengthens this tendency of the shavings to curl.

Which video? The German one shows exactly the opposite of what you say (is it possible that you confused the close- and loosely-set cases?). The Kato/Kawai video shows the shavings curling no matter what. Note that in the Kato/Kawai video there was no mouth, and that may play a role since the shaving is quite weak after being broken and may take the shape of whatever path it follows.

Most of the people here who actually uses close-set cap irons has said the same thing: The cap iron tends to render the shavings "limp" and "flat" (Warren's words). It certainly doesn't "strengthen" anything, as it makes the shaving quite weak.

[Pat Barry]

Which video? The German one shows exactly the opposite of what you say (is it possible that you confused the close- and loosely-set cases?). The Kato/Kawai video shows the shavings curling no matter what. Note that in the Kato/Kawai video there was no mouth, and that may play a role since the shaving is quite weak after being broken and may take the shape of whatever path it follows.

Most of the people here who actually uses close-set cap irons has said the same thing: The cap iron tends to render the shavings "limp" and "flat" (Warren's words). It certainly doesn't "strengthen" anything, as it makes the shaving quite weak.
Yes, the Kato video. By strengthen, I meant increases the tendency to curl. Probably all depends on grain direction, shaving thickness, chip breaker angle and position, etc