Kanna Fabrication Notes

I didn’t feel like working in the shop the last few days.  I put my creative efforts to work at the drawing board, instead.

Trying to find detailed instructions for fabricating a kanna dai is challenging.  There is a decent explanation of the process in Odate’s book for a standard smoothing plane, but even that is a little on the vague side.  So I have been searching the internet and compiling what I can on the topic.  I’ve also been putting that information to the test through trial and error.  Mostly error I’m afraid.  They say we learn more from our mistakes than our successes, so there is that consolation.  Anyway, for better or worse I’ve scribbled down my notes on the making of a basic kanna.

 

kanna_fabrication-sht1of4

kanna_fabrication-sht2of4

kanna_fabrication-sht3of4

kanna_fabrication-sht4of4

Hopefully some of you might find these notes useful.  Also, if any of you spot any glaring errors please let me know and I’ll address them.

Greg Merritt

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20 Responses to Kanna Fabrication Notes

  1. Salko Safic says:

    I love the way you can draw, in my younger days I was pretty good at it but not having touched it for over three decades I pretty much suck it at it now. It would be a great addition to my book.

  2. juryaan says:

    great post as always , Greg.
    I am also trying to get my kanna to work as good as my metal planes .
    I do get some shavings but still not as fine as with the metal planes.

    • Greg Merritt says:

      Thank you Juryaan. Blade sharpening and sole conditioning are the key. I know that is not of much help. The kanna can be touchy when trying to figure it out. Work on one aspect at a time. Make a small change and then try the plane. When you can begin to anticipate the result, everything will begin falling into place.

  3. bpholcombe says:

    Excellent work Greg! This is the most comprehensive set of drawings I have seen on Kanna.
    I have a couple of personal preference points, worth noting for conversation more than anything.
    For the side slots on the dai, personally I lighten up contact as the exit from the top, it’s a weak point so I try to keep the heavy contact from about the pin area down into the bottom of the bed. I used to keep them tight the full way, but Jim Blauvelt corrected me in his class stating that the dai will crack near that point during seasonal change if it’s too tight.

    The hollow on the sole and the relief behind the mouth can be really light on a finish plane, one shavings thickness is enough.

  4. potomacker says:

    You provide such helpful advice and resources, a scholar among gentlemen.

  5. Bob Easton says:

    Superb drawings! As always.

    The drawings alone have filled in a couple of lacunae for me, especially the sole conditioning. While I might never make one of these planes, your explanation and drawings provide enough detail to make one confident about getting started.

    Thanks for documenting what you’re learning Greg!

  6. Sylvain says:

    I really like your drawings.
    It is interesting to see that the lateral grooves are (initially?) made with the blade retracted (10mm).
    What is your experience with no chamfer at the two ends of the sole? (P. Sellers in one of his last public video about making a door once again justify rounding the edges of the sole.)
    Is it customary to name “front” and “back” of the dai as you did?
    Isn’t the bevel on the top parallel to the blade instead of perpendicular or do you mean the angle of the bevel is in such a way that the (geometrical) plane of the bevel is at right angle with the blade plane? What would be the reason for this? (Tap at the best angle with the hammer to untight the blade?)
    The lateral adjustment clearance is only shown on sheet 3. Do yo first make the grooves with the “B” dimension, deepening the grooves afterwards; or do you make your grooves directly for B+2mm?
    Thank you for sharing your knowledge.
    Sylvain

  7. WOW! What a great and comprehensive “sketch”

  8. Stan says:

    Great drawings, Greg. You have talent.

    Two points. First, I have asked many craftsmen in Japan and several professional dai makers over the years regarding the best grain orientation. You listed two options, but you really have three choices for grain orientation; Plainsawn (itame 板目); Quartersawn (masame 柾目); and what you call Rift (oimasame 追い柾目).

    Plainsawn (when oriented properly) wears the fastest of the 3, is the least stable, and definitely the most resistant to splitting when using a hammer to adjust.

    Quartersawn is obviously the most stable, and most wear resistant, but splits relatively easily.

    Riftcut is a compromise, a combination of stability, longer wear, and toughness. This is considered the best orientation for hiraganna.

    Second: The large bevels you show at the sole’s edges are a particular style that Odate and a few others prefer. Some people go a step further and add a sharks grin carved between the ends of the mouth and the sides, believing it helps fine shavings escape the mouth without fouling the sole. In the Kanto area at least, this is seen as evidence of a country bumpkin, Both details add very little, and actually weaken the dai at a critical location. Make some cross-section drawings at osae groove, and perform some calcs, and you will notice the large percentage of material such grooves remove, and corresponding percentage of strength and rigidity that is sacrificed, and all for a more comfortable grip. Makes no sense.

    Keep up the good work

    Stan

    • Greg Merritt says:

      Thanks Stan. Creating drawings, like these, is the best way for me to internationalize an idea.
      While researching the topic of dai blocks, which is limited to english language sources or those with lots of illustrations, I only came across, if memory serves, one reference to plainsawn. While wood selection is always important, it seems to critical ifchoosing a plainsawn block. I felt there are too many caveats when dealing with plainsawn to simply include it as an option on the drawing.

      The bevels along the edges of the sole seems to be one of those “user preference” options. I believe that it could easily range from no treatment all the way to a rebate. Out of curiosity, how do you prefer to treat these edges?

      Sharks grin? If I am understanding this correctly, what you are describing resembles the side escapement on a traditional rebate plane. I have yet to stumble upon any photos of this, but will be on the lookout for an example. Yes, it does seem that the shark’s grin would seriously compromise the structure.

      Thanks for the added information. Its always appreciated.

      • Stan says:

        Greg:

        You are of course right about the limited usefulness of plainsawn dai. But some people prefer them, especially for wider planes, simply because they are tougher, so the option is worth mentioning.

        The “shark’s grin” is not a term I have heard anyone else use. The detail is a simple groove cut at an approximately 45 degree angle from each end of the mouth to the sides of the plane, and sometimes a couple of milimeters up sides. Nowhere near as big as an escapement. You will notice when doing heavy planing that whisks of shavings sometimes hang up in the corners of mouth, These gooves are intended to provide a very shallow recess for these shavings to fit into so that they do not stop the plane from cutting. I don’t recommend them.

        A long time ago (35 years?) I showed one of my old planes I had made with wide chamfers at the sides of the soles like Odate shows in his book to a planemaker and a famous carpenter here in Tokyo. They carpenter laughed out loud, and the planemaker looked disgusted. Being an engineering student at the time, however, I questioned them and analyzed their responses, and quickly realized they were right. Big chamfers are not a good idea in terms of the dai’s strength, rigidity, longevity, and accuracy. They do make the plane easier to handle especially for guys with small hands.

        I prefer a very small chamfer at the sole’s sides, just enough to keep the corners from chipping. I use bozumen (small radiused chamfers) at the top surface’s sides and front. All the other details are pretty much as you described in your drawings.

        There is a more elegant, useful, and difficult way of doing the mouth insert, but the method you show is entirely appropriate.

        Cheers,

        Stan

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