chipbreakers?

[Tom Trees]

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.

I found on an older Bailey style plane with a narrow mouth, that no matter how tight I closed up the mouth I would still get tearout, and in front of the mouth will get rather warm, as in... you wouldn't want to put it against your neck.
This was when I didn't have the knowledge of how to set the cap iron correctly, so had it pretty far back.
I don't like that, and presume a wooden bodied plane would get worn out if you continued at this.

If setting the cap iron, make sure the frog is set all the way back close to, or flush with the casting or it will very be difficult to push
Another thing you may notice, when the cap iron is set for influence in the cut, the plane won't nosedive off the ends anywhere near as readily as it would with moderate smoothing settings.

[Mel Fulks]

Years ago I worked with a cabinet maker who used planes a lot. He said that one thing that could cause tear out was a plane that had been used on the bottoms of sagging doors. The embedded grit would cause wear right in front of the mouth ,the loss of that metal meant the wood was not securely held down and allowed tear out. I haven't bought planes in years ,but I do remember seeing many that had that type of wear.

[Kees Heiden]

Every old plane, wood or metal, I have refurbished had a dip in the sole just in front of the mouth. That is what makes the tight mouth such a red herring. Maybe on a brand new plane, properly flattened, it works for a while, but this is such a high wear area, you just can't trust it.

[Luke Dupont]

Years ago I worked with a cabinet maker who used planes a lot. He said that one thing that could cause tear out was a plane that had been used on the bottoms of sagging doors. The embedded grit would cause wear right in front of the mouth ,the loss of that metal meant the wood was not securely held down and allowed tear out. I haven't bought planes in years ,but I do remember seeing many that had that type of wear.

I tend to find that a tight mouth does just as much, if not more, than a chipbreaker to control tear out. Of course, that tends to be an invariable / unadjustable thing.

[Warren Mickley]

I tend to find that a tight mouth does just as much, if not more, than a chipbreaker to control tear out. Of course, that tends to be an invariable / unadjustable thing.

When you use the tight mouth system, you are limited to fine shavings. So for anyone who dimensions by hand it is a slow and clumsy method.

With wooden planes a tight mouth requires a very sharp edge and things being tight, there is a lot of wear on that edge. When there is wear on the edge, that is when it gets rounded, the shavings tend to get stuck at that point, and it loses its effectiveness as well. If you plane the sole to get a crisp edge again the mouth opens up.

With a double iron wooden plane, you can go a lifetime of heavy use without worrying about the crispness of the mouth.

[Brian Holcombe]

I agree with Warren. A tight mouth is great for a plane without a chip breaker but certainly a chip breaker is the method I prefer for controlling tearout. It is the most effective device that I’m aware of for controlling tearout.

I also agree with Kees, a tight mouth is a very high maintenance item.

One could also argue that the fact that the shavings must be exceptionally thin also has a great impact on how much the ‘tight mouth’ limits tear out.

[glenn bradley]

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?

More like rub salt in the wound.

[Warren Mickley]

When you use the tight mouth system, you are limited to fine shavings. So for anyone who dimensions by hand it is a slow and clumsy method.

With wooden planes a tight mouth requires a very sharp edge and things being tight, there is a lot of wear on that edge. When there is wear on the edge, that is when it gets rounded, the shavings tend to get stuck at that point, and it loses its effectiveness as well. If you plane the sole to get a crisp edge again the mouth opens up.

With a double iron wooden plane, you can go a lifetime of heavy use without worrying about the crispness of the mouth.

In rereading my post of two days ago, I realize the second paragraph is unclear. I wrote:

"With wooden planes a tight mouth requires a very sharp edge and things being tight, there is a lot of wear on that edge." The "edge" I was referring to here is not the edge of the iron, but rather the edge of the mouth, which is what limits the tear out in this method. When it is doing its job, this mouth edge receives a lot of pressure and wear, and needs to be renewed regularly to remain effective.