Origin of "coffin" shape

[Jim Belair]

So when I was first getting into hand tools a number of years ago, I read an article comparing good quality smoothing planes. One was described as a "coffin smoother". Wow, now that's a specialized plane I thought! Wiser (and yes older) now....

I'm wondering about how the coffin shape was arrived at. Good grip?- perhaps but many toted coffin planes are also around. Less friction?- marginally I would think. Style?- maybe worth the small added effort in a wooden plane but considerably more work to make a metal coffin shape.

What think you all?

Jim B

[john brenton]

Here's a blog that already says what it would take me a long time and a lot of typing to say myself...only to have someone tell me I was wrong!!: http://www.fullchisel.com/blog/?p=256

So when I was first getting into hand tools a number of years ago, I read an article comparing good quality smoothing planes. One was described as a "coffin smoother". Wow, now that's a specialized plane I thought! Wiser (and yes older) now....

I'm wondering about how the coffin shape was arrived at. Good grip?- perhaps but many toted coffin planes are also around. Less friction?- marginally I would think. Style?- maybe worth the small added effort in a wooden plane but considerably more work to make a metal coffin shape.

What think you all?

Jim B

[Prashun Patel]

And here I thought all this time it was spelled "coughin'" plane, because it saves you from coughin' up all that dust when you switch to using one from sandpaper....

[Andrew Gibson]

And here I thought all this time it was spelled "coughin'" plane, because it saves you from coughin' up all that dust when you switch to using one from sandpaper....

Funny and true

[Frank Drew]

I don't find this rationale very convincing:

"I also think that the shape allows for its use in conjunction with ... shooting boards. The shape also allows the plane to be held at a skew angle to make a smoother cut with a side rest or shooting board."

To the extent I've thought about it (not very much), I've always assumed that the coffin shape was intended to reduce friction by lessening the amount of plane sole contacting the wood.

[george wilson]

The coffin shape is to make the rear end of the plane narrower to fit more comfortably into the palm of the hand. Reducing the width of the front also makes it easier for the hand to grasp it there.



Reducing the size of the footprint of the plane to reduce friction has nothing to do with it. Making a smaller footprint might actually increase the friction when pushing the plane when it is being pushed. You are able to put more pressure on a smaller area with a smaller footprint.

Consider starting a fire with rubbing the pointed end of a stick against other wood,either by rapid rubbing,or the use of a bow to rotate it. Do you think you could start a fire by using a WIDE ended stick against another?
No,the greater area makes for less friction. The load upon the stick is more spread out. Plain bronze bearings are not made very narrow. They are wide to increase running surface and reduce friction.

There are many errors in the smooth plane shown in the blog mentioned,it shows only a vague knowledge of the coffin smoother: Undeveloped,unrefined shape, undefined bevel around the top edge of the plane,nearly no eyes in the escapement,iron entirely too short,poor orientation of wood grain,wedge not properly detailed,poor shape of area for the palm rest,it is too squared on the corners,and should be more rounded to avoid blisters in sustained use. I would not be writing blogs at this stage of development of understanding. Doing so only serves to confuse and misdirect others.

[Jim Rimmer]

There's an old story about a mother teaching her daughter to cook a roast. The mother cut about 2 inches off the end of the roast and put it on top of the rest before placing it in the oven. When the daughter asked why she explained that that was the way her mother taught her to do it. They asked the grandmother why and she replied that that was the way her mother taught her. They quizzed great grandma and she explained that the pan she had was too short to hold a full size roast so she always cut the end off to get it all in the pan.

Maybe the first guy to make on of these had a piece of wood of that shape.

[john brenton]

Pfew! I am glad I didn't write any of that myself. I'd hate to be the one being excoriated...but I'm guilty of posting it so I guess I'm guilty too. I did however read this: "The contention is that the reduced wood on both front and back will adjust better compared to the thin side walls of the escapement, which would exchange moisture more readily." and am pretty sure that I have read this in a professional planemaker's blog or book or something; that doesn't make it gospel, but we're talking theories.

The coffin shape is to make the rear end of the plane narrower to fit more comfortably into the palm of the hand. Reducing the width of the front also makes it easier for the hand to grasp it there.



Reducing the size of the footprint of the plane to reduce friction has nothing to do with it. Making a smaller footprint might actually increase the friction when pushing the plane when it is being pushed. You are able to put more pressure on a smaller area with a smaller footprint.

Consider starting a fire with rubbing the pointed end of a stick against other wood,either by rapid rubbing,or the use of a bow to rotate it. Do you think you could start a fire by using a WIDE ended stick against another?
No,the greater area makes for less friction. The load upon the stick is more spread out. Plain bronze bearings are not made very narrow. They are wide to increase running surface and reduce friction.

There are many errors in the smooth plane shown in the blog mentioned,it shows only a vague knowledge of the coffin smoother: Undeveloped,unrefined shape, undefined bevel around the top edge of the plane,nearly no eyes in the escapement,iron entirely too short,poor orientation of wood grain,wedge not properly detailed,poor shape of area for the palm rest,it is too squared on the corners,and should be more rounded to avoid blisters in sustained use. I would not be writing blogs at this stage of development of understanding. Doing so only serves to confuse and misdirect others.

[george wilson]

You aren't guilty of anything but being mislead,John.

This might not be sugar coated,but it is the truth. There are some of these self appointed "gurus" that have very little knowledge,but have such enormous egos they think they know many times more than they really do. One who USED to post here spent endless words about the superiority of using bronze for saw screws when he can't even design a decent saw handle. It foes on forever. The internet is full of their blogs,web pages,etc..

I just get enough of it sometimes.

[john brenton]

To be honest I just googled "reason for coffin smoother shape" and posted the first result that kind of had all the different theories. I don't know the blogger, and have never read anything of his in the past. I don't think he was really posturing himself as a guru though...take it easy George!

I don't pay attention to woodworking blogs or magazines much for that reason. If I really want to know something I'll either ask someone I really esteem or try it myself. Are you talking about the saw maker that charges $500 for a sawplate with a hideous handle attached? If so...kudos to him for being an entrepreneur and everything, and I hate to offend, and I'm not implying I can do better...but ...wow.

Do you entirely disagree with the stability/moisture theory?

You aren't guilty of anything but being mislead,John.

This might not be sugar coated,but it is the truth. There are some of these self appointed "gurus" that have very little knowledge,but have such enormous egos they think they know many times more than they really do. One who USED to post here spent endless words about the superiority of using bronze for saw screws when he can't even design a decent saw handle. It foes on forever. The internet is full of their blogs,web pages,etc..

I just get enough of it sometimes.

[george wilson]

John,I know the blogger,and he is trying to be a guru. No,I'm not talking about the $500.00 saw maker. He hasn't been here in a while. I think he and the other person in question are trying to start their own forum. Not sure.

Mr. blogger made the sweeping statement a while back here that the old laminated steel irons were the best ever made,and could never be improved upon(or words to that effect).

Yes,I got a little grumpy when that guy popped up!!! He and his saw maker buddy are both woodworking wannabees who think they are gurus.

[Frank Drew]

The coffin shape is to make the rear end of the plane narrower to fit more comfortably into the palm of the hand. Reducing the width of the front also makes it easier for the hand to grasp it there.

Perhaps originally, with wood-bodied planes, but there are many metal-bodied infill coffin-shaped smoothers with both front and rear handles, that is, the narrowed sides can't be explained as just a way to fit the hands. If there wasn't a good reason to continue with that design they certainly wasted a lot a time and money -- making a curved-sided dovetailed plane body is certainly harder to do that a straight-sided one; maybe that's why all those old British planemakers went out of business .

Reducing the size of the footprint of the plane to reduce friction has nothing to do with it. Making a smaller footprint might actually increase the friction when pushing the plane when it is being pushed. You are able to put more pressure on a smaller area with a smaller footprint.

Reducing the sole size on coffin-shaped planes reduces the plane's weight by whatever amount, and that makes them easier to push: As the weight of an object increases, more force is required to move the greater mass (F=ma).

[David Weaver]

I'm inclined to believe also that it's an issue of grip, and it may be an issue of style to go along with it.

The weight of a plane itself can't explain the amount of downward force that exists while you're planing given how much bodyweight a user will lean down into the plane.

I would imagine that the planemakers had plenty of selection that was seasoned for years, especially in the 18th and early 19th centuries. I doubt Larry Williams is wrong about much or anything that he says about planes, though.

I have used square wood smoothers and coffin wood smoothers for long periods of time. I would bet that anyone who worked with one constantly would instantly prefer the coffin design for comfort vs. a square-backed plane.

[Dale Sautter]

I know it wasn't all wood but... sure would have/still would love to have a "Loopy"

[David Weaver]

I wonder what is the ultimate expression of the planemaker's art if it isn't infills.