Influence of the Cap-iron on Hand Plane

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    interesting, I guess I use the cap iron just to hold the iron and not as a chip breaker. But I don’t think my standard cap iron would get close to 80 degrees.

    Dallas, Texas


    Thanks Johan, Interesting video buddy.


    Interesting. Thanks for the link Johan.

    Several observations:

    1) The cap iron, or chip breaker, in the film is only 0.3-0.1mm from the cutting edge, which is much less than the usual recommendation of 1/32″ (~0.8mm).

    2) The test device is essentially a chisel plane. There is no mouth like with a conventional plane. I am wondering how much a tightly closed mouth would affect results.

    3) I was impressed to see how effective a shallower cut is at reducing tear-out. The physics makes sense, but the benefit seems exponential.

    4) The 80 degree breaker in the film only appeared to be a mere 0.4mm tall. A typical Bailey style chip breaker could easily be modified by grinding/honing a slight vertical on the leading edge. Just saying…

    -Scott Los Angeles


    Good points Scott, maybe I I give it a try.

    I was looking around for some more info and found this:

    From Planecraft C&J Hampton Ltd. 1972 impression sponsored by Woodcraft:

    Cap Iron Settings:

    For rough work: 1/32″ to 1/16″ from the edge

    For finishing work: 1/64″ from the edge

    For hard woods with irregular grain: “as close as you can get it to the cutting edge”

    The publishing history of this book is as follows:

    1934 – first published
    1943 – 2nd impression
    1945 – 3rd impression
    1950 – 4th impression (revised and enlarged)
    1953 – 5th impression
    1954 – 6th impression
    1959 – 7th impression (revised and enlarged again)
    1972 – Woodcraft sponsored printing of the 7th impression from 1959.

    So from what I get it was known how the cap iron/chip breaker could help with tear out even back in the day.

    Dallas, Texas

    David Gill

    Very interesting, It would be interesting to see what the different iron sharpening methods would have , Convex , concave with and without micro bevels

    Wigan, Lancs. England :

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