A tightly set mouth to control tear-out.

[Stewie Simpson]

　
A plane is designed to slice a shaving off a board. This happens when the force to slice wood fibers is less than the force to simply tear it away from the board. A sharp cutting edge is the best way to ensure slicing the fibers rather than tearing them, but for critical cuts as when using a smoothing plane for a perfect final surface, a tight mouth will also help. The fibers cannot tear up while the sole of the plan is holding them flat. The sole will do this until the edge of the mouth is reached, freeing the fibers of pressure and allowing them to pull up. A tight mouth minimizes the length of this no-pressure zone. Too tight, however, and the shaving cannot fit through and will jam. For non-critical cuts, the mouth can be left relative wide open. http://www.walkemooretools.com/wp/wp...and-Planes.pdf

[Patrick Chase]

Do you have a point?

Seriously, this falls into the category of "things every plane user should already know". Sharpness and depth of cut are both even more important than tightness of mouth in regulating tearout, and cap iron configuration is at least at a similar level of importance.

There are some interesting tradeoffs between mouth and cap iron tightness, though - if you try to crank both to 11 you often end up jamming, and there's no universally right answer w.r.t. which to back off and by how much. It depends on the wood, depth-of-cut, and a host of other variables.

Since you're obviously trolling I'll take the bait: The slides you linked to expound an incorrect interpretation of the role of the "chipbreaker". It's a widely held view, but incorrect nonetheless.

[Warren Mickley]

Years ago I had a Latin teacher who was also an ordained minister. He said preachers often raise their voices when the argument is weak.

[Stewie Simpson]

Here we go Patrick.

from the manufacturers site;

https://www.lie-nielsen.com/nodes/42...n-chipbreakers

[Patrick Chase]

Here we go Patrick.

from the manufacturers site;

https://www.lie-nielsen.com/nodes/42...n-chipbreakers

I don't see anything contradictory there. It seems fairly clear that Stanley did exploit the cap iron's stiffening properties to enable thinner blades, even if that wasn't the original or primary purpose of the cap iron.

Interestingly enough Lie-Nielsen's views seem to be evolving in this respect, at least as evidenced by the "out-of-box" tune on their planes. My new #10-1/4 arrived with a steep microbevel on the leading edge of the cap iron, and with the cap-iron set <1/32" back from the blade edge. The L-N #8 that I got about a year ago had a more traditional setup (~25 deg bevel all the way to the edge, cap iron set ~1/16" from the blade edge). If anything you would expect to see a less aggressive cap iron setup on a Jack-class plane like the 10-1/4...

[Brian Holcombe]

To truly control tear out one must wear a proper planing robe.

[Jim Koepke]

I don't see anything contradictory there. It seems fairly clear that Stanley did exploit the cap iron's stiffening properties to enable thinner blades, even if that wasn't the original or primary purpose of the cap iron.

Perhaps historical texts might shed some light on this. From looking at some of the images posted by someone in an earlier discussion on this might suggest early cap irons worked to add springiness into the equation. There are natural vibrations that can occur in the operation of a plane. Vibrations could loosen a wedge. Adding a cap iron may be a way to dampen vibrations either by more mass or a springing action to dampen vibrations.

Thicker blades need more energy transferred to initiate a vibration. Tapered material is also good at resisting harmonics.

jtk

[david charlesworth]

My favorite smoothing plane has a thicker blade (Hock), heavy chipbreaker (L-N) and a 0.004" mouth.

This works very well most of the time , but when faced with complex, dense, brittle timbers it can cause significant tearout.

I have come to the conclusion that a tight mouth is not so effective as high effective pitch, or ultra close C/B settings.

Currently I am trying to decide which technique I prefer.

High EP is less of a fiddle and I am very familiar with the 25 degree backbevel which I like.

David Charlesworth

[Kees Heiden]

I agree with David, a tight mouth is not nearly as effective as a high cutting angle or a very close set capiron. The high cutting angle has its own disadvantages, so it is no wonder the entire woodworking community turned to double iron planes in the late 18th/early 19th century.

There are two, maybe even three disadvantages of a tight mouth.
- Is is not so very effective.
- It only works with an absolutely flat sole. Or better said, the front edge of the mouth MUST press down on the wood. Even a slight hollow in the front of the mouth or some rounding of that edge completely negates the effect. This happens to be the prime wear spot of planes, each and every antique plane I have refurnished had a significant hollow in this spot.
- To be effective the mouth needs to be in the 0.1 to 0.2 mm range. That is TIGHT! Setting a Bailey style plane evenly across the width to have such a fine mouth is a lesson in frustration. It is equally difficult in a wooden plane. Not impossible I suppose, but for sure not easy. Try to make a wooden plane with a 0.1 mm mouth, a 70 degree wear angle that still feeds the shavings freely. And then, after one or two sole flattening sessions, the mouth allready opened to more then 0.2 mm and the effect is gone.

[Stewie Simpson]

If not already confusing enough, we now need to consider (CDA) Combined Deflection Angle of the shaving.
http://www.popularwoodworking.com/wo...h-chipbreakers

[Brian Holcombe]

The mouths on both smoothing planes that I use are set very large by most standards and neither plane has trouble with tearout or with clogging. By large I mean 1/16"~ The bedding angles are 45 degrees and 38 degrees.

[george wilson]

It has already been proven by the now well known Japanese video showing a laboratory controlled cap iron experiment. When the cap iron was set very close to the cutting edge,even planing against the grain,tear out was eliminated.

If LN wants to stubbornly deny the use of the cap iron,that's their option. Plane users like Warren Mickey have proven the use of the cap iron is very effective. He won a big contest using an ordinary Stanley plane.

Who are you aiming this at,Stewie? David Weaver? ANOTHER post like this is only going to result in a big fight. A fight that has already been fought,and won by those who know how to use the cap iron properly.

It doesn't matter how many sources you can quote. They were only written by those who do not know how to use the cap iron. Any one of us could submit an article pro or con to a woodworking magazine,and if they needed the material(which they always do!),they would print it.

[Stanley Covington]

To truly control tear out one must wear a proper planing robe.

Don't forget the embroidered planing slippers.

[Kees Heiden]

No need to take it all too seriously! Stewie is just janking our chains, and I'll be happy to bark anytime.

[george wilson]

I agree,Kees. There is no need to re open a subject which has already been done to death!! Sharpening is another one which should be banned!!!