Wooden Plane Mouth Location - Geometry?

[Bill Haumann]

How does the location of the mouth affect the effective length of a plane, or does it not?
Every now and then I see an old wooden jointer with the mouth about 1/3 from the heel instead of 1/3 from the toe. I recall reading that 1/3 from the toe is the norm, but not why.

- Bill

[Metod Alif]

A Guess
It looks that 1/3 from the toe brings the center of plane's mass near middle of the sole. It would be nice to hear from heavy users how the location of the mouth affects the handling of a plane.
Best wishes,
Metod

[john brenton]

I haven't measured it, but my 24" ulmia's mouth is pretty dang near close to center, as opposed to my other english try plane that is set a little more forward. It affects the effective length because you want the toe of the plane to ride on the surface as far as possible so that it can ride up on the flat, or the hill, before the cutting edge hits.. For example, when you go to plane a convex side of a plank, if you're planing correctly you'll end up with both ends rough and a planed, but slightly convex, center, with the planed center getting longer and longer until the whole board is planed. With a longer toe that is easier to do because you can put more pressure on the toe. If the board is warped enough, you'll be putting enough pressure on the toe to where you're cut may start over an inch or so past the edge of the board. If the toe were too short, you would be relying too much on luck and you'd most likely be following the curve instead of planing it off. Where it should start an inch in, you'd be starting the cut at the edge and in the end you'd have the same warped board, just a thinner version of it. Is that too obvious, or what you were asking about?


How does the location of the mouth affect the effective length of a plane, or does it not?
Every now and then I see an old wooden jointer with the mouth about 1/3 from the heel instead of 1/3 from the toe. I recall reading that 1/3 from the toe is the norm, but not why.

- Bill

[Mike Henderson]

I think the mouth is forward on most wooden planes because the blade angles back and you need enough space at the back of the plane to place your hand comfortably. I doubt if the operation is affected a great deal as long as the mouth is not too far forward.

Mike

[Zahid Naqvi]

I have a few Sandusky and some Bailey transitionals, 1/3 front of the mouth and 2/3 behind the mouth seems to be the general ratio. For example I have a 22" Sandusky razee style plane, the length in front of the mouth is 7" and 15" behind it. The point at which the blade sticks out of the top of the plane is exactly 11". I suspect the blade is pushed forward to make room for the handle. Logically speaking you would probably want the mouth to be exactly in the middle to get equal leverage when entering the work piece as well as exiting.

[Wilbur Pan]

Once you get the entire length of a plane onto the board, the reference length is pretty much determined by the length of the sole from the mouth to the back end of the sole. That's where most of the downward force will be during the planing stroke.

I don't think there's anything specific about wooden jointer planes that determines this particular placement of the mouth. Photoshopping a picture of a Lie-Nielsen #7 together with a picture of a wooden jointer plane (William Ash, 26" long) that I found on the Internet shows that the mouth placement is nearly identical. So is the tote placement, and where you would put your left hand at the front end.

https://lh3.googleusercontent.com/_a3R4RhWn1Is/TdF6jl7jmWI/AAAAAAAABbc/wOruf7UjzfY/s640/Woodie%20vs.%20metal%20jointer.jpg

Interestingly, the mouth of a Japanese plane is also placed pretty close to the 1/3-2/3 divide, but with the longer part in front, due to the fact that Japanese planes are pulled instead of pushed.

[Kees Heiden]

The Germans put the iron a lot further back. Well, it probbaly works allright ( I have no experience) but I think it looks but ugly.

194903

[Wilbur Pan]

The iron in the German plane isn't that much farther back. More Photoshopping:

https://lh5.googleusercontent.com/_a3R4RhWn1Is/TdJ5imLEduI/AAAAAAAABb4/ZxYROGZJ6to/s640/Woodie%20vs.%20metal%20jointer%202.jpg

If the picture you had of that ECE jointer was more of a direct side view, the mouth position would turn out to be even more forward than it appears in that particular photo.

[Pam Niedermayer]

The Germans put the iron a lot further back. Well, it probbaly works allright ( I have no experience) but I think it looks but ugly.

It works great, much better than the #7 I replaced with it. It isn't ugly, it just works; and the Primus model is great stuff.

Pam

[David Weaver]

The Germans put the iron a lot further back. Well, it probbaly works allright ( I have no experience) but I think it looks but ugly.

194903

It is ugly. Works fine, though. Can't say I like it better than a bench plane so much as pam does (it's just different), but once you get used to the feel of the continental planes, they are nice to use.

I think most of the "ugly" is due to the fact that anyone still manufacturing wooden planes at mid-market prices (except maybe in china) is not doing much handwork, which dictates how the finished product looks - it reminds me of wooden toys from the 70s and 80s.

[john brenton]

I really like my Ulmia jointer now. The example above is an ECE, that is actually more refined than the Ulmia, if that gives any clue as to how unattractive the Ulmia is. All I had to do was sand the handle and it's now a really comfortable and sweet user. The look does take some getting used to though.

It's nothing like an English pattern...the 24" ulmia is like a skinny beechwood U-boat torpedo.



It is ugly. Works fine, though. Can't say I like it better than a bench plane so much as pam does (it's just different), but once you get used to the feel of the continental planes, they are nice to use.

I think most of the "ugly" is due to the fact that anyone still manufacturing wooden planes at mid-market prices (except maybe in china) is not doing much handwork, which dictates how the finished product looks - it reminds me of wooden toys from the 70s and 80s.

[Kees Heiden]

It works great, much better than the #7 I replaced with it. It isn't ugly, it just works; and the Primus model is great stuff.

Pam

Well, I still think it's ugly. :-)
But it's good of them to still produce these things.

I do like the German horned planes though. I have an old Ulmia reform smoother and it is very stylish (and is a blast to work with).

[Pam Niedermayer]

...I do like the German horned planes though. I have an old Ulmia reform smoother and it is very stylish (and is a blast to work with).

I've got a no name horned scrub that I like a lot. On joinery planes, though, they're tall enough that you don't really need a handle of any sort on the front; and using that tallness helps keep the plane level during the stroke. I say ugly is as ugly does. And if I see another movie in which first thing a male actor says some little girl is pretty or the like, I'll probably barf all over the theatre.

Pam

[Kees Heiden]

There have been horned joinery planes in the past overhere in Europe a lot. You see them on all the old paintings. But the front horn disappeared, probably with a reason. And I like pretty in things. And in girls too :-)

[Pam Niedermayer]

...And I like pretty in things. And in girls too :-)

Fine, you go to the movies. I think the ugliest planes are the metal bench planes. So what?

[Zahid Naqvi]

ok kids let's get back on topic of plane geometry :rolleyes:

It just occurred to me while looking at the comparative pictures Wibur posted, that the hand planes of the yesteryears were used in production shops. It seems the geometry may have been defined to place the handle at a location where it was more ergonomic to handle the planes. If I am using a plane all day to dimension boards I would definitely want the handle to be as close as possible to the center of gravity. A front heavy or rear heavy plane would be very uncomfortable to use and pick up.

[Kees Heiden]

I think you nailed it.

And that's probably a good reason why I don't like that German style. The English planes look balanced, a joy to pick up. The German one looks like the handle was an afterthought, unbalanced, out of whack. But taste is always subjective of course.