Full Chisel Blog

December 10, 2008

Boat Shape, Coffin Smoother

Coffin Smoother

It is interesting, these theories as to why the coffin smoother has its unique boat shape.  Prior to 1700 smoother planes were rectangular in shape.  Moxon illustrates both types in 1703.  {Traditionally the actual coffin for burying people was that shape to: save wood, the hole is easier to dig and the coffin is easier to carry being that particular shape.}

Moxon Smoother

A suggestion is that it would have been easier to hold in the hand than a rectangular block of wood.  Another is that it reduced the area of the sole of the plane that is in contact with wood, thereby reducing friction.  One of the best and well thought out is that of movement of the wood due to seasonal changes in temperature and humidity.  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.  But the blade is covering the end-grain of the bed/frog, so this presents a problem.  Also there is much more wood behind the blade in the heal than in the toe of the plane.

 When using this plane Mercer suggest that the plane could wiggle into corners and while this plane will not get you any closer to the edge than one of a rectangular configuration, the boat shape of the plane would allow a bit of a skew when working near and obstruction such as a molding.  Now this would be a rare occurrence as the smoothing would be done before any moldings were applied.

Durer Melencholia

Durer illustrates a boat shape (coffin shape) plane in Melencholia in 1514.  The smoother from the 1596 ill fated Dutch expedition to Nova Zemlya is rectangular in nature and horned as well.  Mercer suggest the engraving is representing carpenter’s tools, but it looks more like cabinet maker’s tools to me.

Shorter length planes do not flatten boards or panels, other bench planes like a joiner, jack or fore plane are used for that purpose.  The short body follows any troughs or ridges relative to its length.

So here is my take on why the smoother is this shape.  I will preface this by saying that our ancestors weren’t stupid and did things for a good reason.  And if something comes into common use and in many parts of the world then it must have been a good design.  This design theory falls apart in the late 19th century when business and marketing had more influence than practicality.

The smoother is used to remove ridges left by longer bench planes and to bring the surface smooth.  So why the coffin shape?  Perhaps for all of the suggested theories, so I will add mine to the fray.

The curvilinear lines of the coffin/boat smoother allows this plane to have a shorter configuration by using the plane on the skew.  When the blade is askew the grain of the wood along which the ridges and valleys formed by longer bench planes, the geometry of the plane changes making the overall length effectively shorter that if it were of a rectangular format.  This would allow the plane to get down further into the valleys and troughs to smooth out any problem areas.

I also think that the shape allows for its use in conjunction with a side rest (bench hook) and 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.  It is possible to grasp the plane in one hand while using it with these bench appliances.  I do use a fore plane to straighten the board then change to a coffin smoother to produce the final finish on the edge.

So there are the theories I have heard of and a couple of my own.

Stephen

19 Comments »

  1. Been following your blog for a few days.

    I just had one question. The Bar that you have on all of your projects.

    What is this for? Is this for contrast or just a Trademark type of a think?

    Handi

    Comment by Handi — December 10, 2008 @ 8:52 am

  2. Handi,

    It is called a gnomon and is used for photographic scale. It is 6 inches long with 1 inch squares, ebony in holly.
    It allows you to scale the object to know its exact size.

    Stephen

    Comment by Stephen Shepherd — December 10, 2008 @ 4:11 pm

  3. Stephen, Larry Williams (Clark & Williams) explained in a seminar I took at the WIA conference that the shape of the coffin smoother is to make the wood more stable. He said the curve exposes more end grain on the sides. That made sense at the time, but then I wondered why all wooden planes aren’t curved like that. Planemakers added decorative touches to their planes (as you know) so I lean towards the comfort aspect and the aesthetic appeal of the shape as to why they were fashioned that way. Of course, my opinion is purely subjective.

    Comment by The Village Carpenter — December 11, 2008 @ 9:14 am

  4. VC,

    I have to agree with you about comfort and looks, and it would seem to me that the larger the plane the more concern for stability. I can also see that the shape would place the center of gravity more in the center of the plane from side to side and the bed and escapement cavity would lower the center of gravity. And the older I get the more involved, informed and concerned I am about gravity.

    Stephen

    Comment by Stephen Shepherd — December 11, 2008 @ 4:48 pm

  5. Stephen: Cool Thanks, I may have to make one of them, that would come in Handy.

    Is that the ONLY Length? or can you make them bigger to accommodate?

    Handi

    Comment by Handi — December 11, 2008 @ 8:02 pm

  6. Handi,

    No you can make them any size, I have also seen them 12 inches long. I have seen one that is gimbaled and hangs from a stand to show exact vertical in the photograph. The important thing is that it is the same size in every picture. I use one inch squares on mine and it is shorter to carry around. I do try and put it in every photograph I take that needs scale.

    Stephen

    Comment by Stephen Shepherd — December 12, 2008 @ 8:12 am

  7. Gimbaled? And just recently another woodworking blogger used the word Wabe. Suddenly, I feel as if we are entering the Looking Glass world.

    I like the idea of the Gnomon. I used to use a boxwood folding ruler as a Gnomon when scanning material for archival purposes. I may just start that habit once again. Seeing your Gnomon gives me a much better sense of proportion than would guessing or trying to gauge size by near by objects.

    Gary

    Comment by Gary Roberts — December 14, 2008 @ 12:22 am

  8. Here’s a couple of more thoughts on the shape of the smoother: If you buy into the idea of corrugated soles for metal planes, less surface area in the coffin smoother as compared to a purely rectangular form would lead one to expect the coffin smoother to have a lower coefficient of friction.

    I don’t really buy that — I don’t think that the average Galoot could tell the difference between the two.

    I suggest (after great pondering and deep thought, right elbow on left knee, etc.) the answer lies within the 7 Last Words: “We’ve always done it that way, before!”

    Mack

    Comment by Mack — December 16, 2008 @ 9:44 am

  9. Mack,

    Those are words of wisdom. Another reason for the more comfortable shape is that perhaps the smoothing plane was the most used bench plane, so comfort was important. I am going to build a rectangular smoother of the same dimensions as this coffin shape and see if I can determine any difference.

    Stephen

    Comment by Stephen Shepherd — December 16, 2008 @ 2:59 pm

  10. Stephen,

    Let me join the last comments on the historic reason for the shape. The Romans brought the plane north the Alps. Germanic craftsmen just not copied it, but transformed them and modified them up to their needs. Roman shapes are square and angular, Germanic are decorative, rounded, chamfered and fancy, but have narrower irons.

    After the almost complete change from the bolt wedge to the cheek wedge system during the 15th century, the shaving aperture had to be rethought and made bigger. In western Europe this meant to widen only this part of the plane. Dürer’s plate is the prove.

    Personally I think both shapes are anchored in western civilization and the coffin shape is a Germanic or say at least Scandinavian legacy.

    Marc

    Comment by Marc — January 18, 2009 @ 11:56 am

  11. Marc,

    Thank you for your comment and that is a very good argument, I think the Durer’s blockprint is an early one as is the Jan Van Vleit showing the shape. I have noticed some differences in use between the Moxon smoother and a typical English coffin smoother. Both are bedded at the same angle but the shape makes for different use.

    Stephen

    Comment by Stephen Shepherd — January 19, 2009 @ 8:11 am

  12. Hi! I have been reading your comments and I summize that it is all to do with the size and shape of the tradesmans hand. You will note that some coffin planes have indentation where the thumb and index fingers will grasp the back of the plane. I believe this is all for comfort after all they were working longer hours than we do and did not have the luxury of complaint. Therefore they either made do or made adjustment to their tools for comfort. Just my summation but when I’m in the workshop I’m glad the coffin plan is NOT rectangular.

    Comment by Nicky — March 17, 2009 @ 7:24 am

  13. Oh one thing I forgot to say …. I have a wee coffin plane that I absolutely love to use. She is a real sweety, the plane just cups into my hands perfectly and just peels really wafer thin slices from what I’m working on. Yes I am a collector, I believe the term is GALOOT, I’ve been calling my husband that for years (never new I could be right in everything) Oh well that’s being a woman for you! Ha sorry just stirring it up! It’s 2.30am and I can’t sleep, shen that happens I start getting cheeky!

    Thanks Guys

    Nicky

    Comment by Nicky — March 17, 2009 @ 7:31 am

  14. Nicky,

    Thanks for your comments, and get some rest. The shape of the coffin smoother is very probably to fit the shape of the hand better than the rectangular planes. I have used one very large coffin smoother that would have been awkward if it were a square block. However the small Moxon smoother I made, feels good in the hand (not as comfortable as a coffin smoother of the same size) and I am not sure I can tell any difference in performance.

    Stephen

    Comment by Stephen Shepherd — March 17, 2009 @ 7:58 am

  15. Hi Stephen,

    When you say very large coffin smoother how big would that be please? Also how small is the Moxon smoother you made, any chance of a picture?

    Regards Nicky

    Comment by Nicky — March 17, 2009 @ 9:39 am

  16. Nicky,

    I am not sure but I think somewhere on my blog is a picture of that large smoother. Also the Moxon smoother is also listed several times. Use the search function on the right and you will find reference. The Moxon smoother has a 1 1/2″ wide blade, if I remember correctly the large smoother was 2 1/4″ wide.

    Stephen

    Comment by Stephen Shepherd — March 17, 2009 @ 12:04 pm

  17. 13.Oh one thing I forgot to say …. I have a wee coffin plane that I absolutely love to use. She is a real sweety, the plane just cups into my hands perfectly and just peels really wafer thin slices from what I’m working on. Yes I am a collector, I believe the term is GALOOT, I’ve been calling my husband that for years (never new I could be right in everything) Oh well that’s being a woman for you! Ha sorry just stirring it up! It’s 2.30am and I can’t sleep, shen that happens I start getting cheeky!

    Thanks Guys

    Comment by งานโคโยตี้ — June 14, 2011 @ 2:49 am

  18. Stephen, Larry Williams (Clark & Williams) explained in a seminar I took at the WIA conference that the shape of the coffin smoother is to make the wood more stable. He said the curve exposes more end grain on the sides. That made sense at the time, but then I wondered why all wooden planes aren’t curved like that. Planemakers added decorative touches to their planes (as you know) so I lean towards the comfort aspect and the aesthetic appeal of the shape as to why they were fashioned that way. Of course, my opinion is purely subjective.

    Comment by cupcake — October 17, 2011 @ 8:03 am

  19. It’s much more than ‘comfort and looks’. You can skew a coffin plane slightly or even more than you can with a lever in the iron plane.This is it’s advantage along with some room for fingernails in the way sometimes held is an unintended offshoot. I doubt the ‘stability story….you have end grain in a square plane if cut out the same way…Block planes have a specific purpose and developed in several ways. Coffin planes also have a specific purpose. Short planes are found in several guises…so why the coffin shape?

    The purpose of these shorter planes is not to do a long smoothing job but to remove the hills
    in short areas..all a part of the planing process..They remove valleys and the bends in timber
    only in the sense of lowering the hills so a longer plane can do its job more effectively,
    rather than tilt over the hills.I have watched the process of planing for fine cabinet work and
    several planes are used in the process…and without hesitation to re-set resharpen when the
    shavings tell a story.

    Being able to skew it helps when the rise is owing to a knot in the timber which the long plane tends to jump and the thin Stanley and other thin blades flex at or chatter.You can do this much more readily with a wooden coffin plane.

    One shouldn’t lose track of the fact that when there were such things as quality cabinet makers and quality carpenters of the old school. My father was a world class if not better cabinet-maker-French polisher and most of his timber came in hand picked but rough-sawn. He had jointers, combined with dowelling tables post his return from WW11 ..yes… and a long trolley fed sanders came along in the 1960’s yes, but that was for speed on lesser works such as lounge repairs but all the cabinet work was hand done to perfection. He often enough used the dowelling table though but did an awful lot of work with a brace and bit right up into his 80’s. I never saw him use a drilling machine or as the awful practice is today…and it is very unprofessional…using HSS drills (and hole saws) in power tools on timber…Any real, professional,expert knows why.If they don’t then they aren’t.

    Timber was very very commonly bought as rough sawn as I said even by carpenters…it wasn’t sanitised, machine planed,knotty, bent, poorly dried crap we get today through places like Bxxxxxgs and other companies which have destroyed the decent tool market….selling junk from China ‘under licence’and timbers rushed into sale from the ruining of rain-forests. All of us who hold and maintain and use ‘vintage’ and tools are doing the world a favour it doesn’t realise is happening. LOL!!

    Comment by Tony — March 22, 2012 @ 5:34 pm

RSS feed for comments on this post. TrackBack URL

Leave a comment

Powered by WordPress