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Hickory: Rings per inch, heartwood vs sapwood, etc.

Discussion in 'Axe, Tomahawk, & Hatchet Forum' started by Steve Tall, Sep 25, 2014.

  1. Steve Tall

    Steve Tall

    Aug 28, 2010
    Recent mentions of the ideal number of growth rings per inch spurred me to find some data:


    In hickory the wide-ringed wood, often called "second growth" hickory, is preferred. Figure 14, based on commercial hickory grown in good situations, shows that the work or shock-resisting ability is greatest with wide ringed wood that has from 5 to 14 rings per inch; is fairly constant from 14 to 38 rings, and decreases rapidly from 38 to 47 rings per inch. The strength at maximum load is not so great with the most rapid growing wood; it is at a maximum with from 14 to 20 rings per inch, and again becomes less as the wood becomes more closely ringed.

    The natural deduction is that wood of first class-mechanical value shows from 5 to 20 rings per inch, and that slower growth yields poorer stock. Thus the inspector or buyer of hickory should discriminate against timber that has more than 20 rings per inch. Exceptions exist, however, in the case of normal growth upon dry situations, in which the slow-growing material may be strong and tough.


    quoted from The Commercial Hickories by Anton T. Boisen and J.A. Newlin
    USDA Forest Service Bulletin 80, Issued October 27, 1910

    (To be continued...)
     
  2. Steve Tall

    Steve Tall

    Aug 28, 2010
  3. Steve Tall

    Steve Tall

    Aug 28, 2010
    Taking a closer look, however, it doesn't seem so cut-and-dried. From the graphs, it's clear that for hickory with 5 to 20 growth rings per inch, the "Strength At Maximum Load" is around 11,000 (the units aren't labelled), but for between 20 - 35 rings per inch, the Strength doesn't drop below 10,000. So that's only about a 10% reduction in strength if you have 35 rings per inch, compared to the ideal. Is this enough reason (by itself) to reject a handle, or will it still be strong enough (if there's no problem with grain runout, etc.)?

    Looking at the graph of shock-resisting ability ("Bending Work to Maximum Load"), 5 - 11 rings per inch gives the highest values, while there's a plateau between 14 - 38 rings with roughly the same values.

    Based on this data, it looks like the best hickory would have 5 rings per inch. Increasing from 5 to 11 rings per inch would slightly increase the strength (less than 5% increase), but the shock-resisting ability would decrease by 17% (or so). Between 11 - 35 rings per inch, the shock-resisting ability is about the same, while strength drops slightly as the number of rings increases.

    So my takeaway from this data is that I would not reject a handle solely on the basis of rings per inch, unless it was over 35 (or so) rings. Especially since "in the case of normal growth upon dry situations... the slow-growing material may be strong and tough". In other words, the slow-growing, many-ringed hickory could be stronger and tougher than shown in the graphs.

    [​IMG]
     
  4. Steve Tall

    Steve Tall

    Aug 28, 2010
    About the effects of heartwood and sapwood, here's some information from the same book:


    [​IMG]


    "Table 16 gives the results of tests from selected pieces lying side by side in the same tree, and also the average values for heart wood and sapwood in shipments of the commercial hickories without selection. It shows conclusively that the transformation of sapwood into heartwood does not affect either the strength or toughness of the wood. This conclusion is also confirmed by Forest Service Circular 142, which shows that, weight for weight, sound hickory is equally strong regardless of color. Therefore the user of hickory should not discriminate against heartwood in buying stock. It is true however that sapwood usually is more free from latent defects than heartwood."
     
    Last edited: Sep 25, 2014
  5. Steve Tall

    Steve Tall

    Aug 28, 2010
  6. Steve Tall

    Steve Tall

    Aug 28, 2010
  7. 300Six

    300Six

    Aug 29, 2013
    Annular ring thickness may have 'perfect world' ideals but it your chosen handle has good grain orientation and no run out over it's length (and it's bona fide hickory and not spruce/pine/fir/poplar etc) then you really don't need to worry about a thing.
     
  8. Steve Tall

    Steve Tall

    Aug 28, 2010
    Some axe users would say that "good grain orientation" is another 'perfect world' ideal that you "really don't need to worry about".

    The USFS, with all their experience, doesn't seem to care at all about axe handle grain orientation in their FSS axe specs.

    See http://www.bladeforums.com/forums/showthread.php/1024233-Bummed-about-my-new-Council-boys-FSS-axe
     
    Last edited: Sep 25, 2014
  9. cityofthesouth

    cityofthesouth

    Jan 29, 2014
    All that's left Steve, is to write the final post saying, "in conclusion, none of the 'handle wisdom' has any real merit and it's been known for at least 100 years based on this copyright date". Make it a sticky and 'have nice day'.
     
  10. Twoinch

    Twoinch

    197
    Aug 7, 2014
    all i have to ad to this, is that it is very hard to find hickory handles with more than about 17-20grpi in todays market. the highest i have come across is a 19grpi heartwood handle. about 95% of the stuff i see is less than 15grpi, with the majority less than 10grpi.

    i will agree with 300, in that any handle you find in todays market will be fine in the GRPI sense, and your best bet is to look at grain orientation and run-out foremost.
     
  11. Twoinch

    Twoinch

    197
    Aug 7, 2014
    also would like to add that, especially with single bit ax handles(boys/fawn). the reason vertical grain is important, is the fact that to get good run-out, the grain must be nearly vertical.
     
  12. Steve Tall

    Steve Tall

    Aug 28, 2010
    ???

    I presented some of the data behind the Forest Service's guidelines (or handle wisdom) about "rings per inch" and heartwood/sapwood. Draw your own conclusions.

    My own takeaway is that the Forest Service is perhaps over-cautious in its recommendations about rings per inch, and perhaps under-cautious with its assurances that heartwood is a good as sapwood. (Since heartwood reportedly has more hidden defects than sapwood.)
     
  13. cityofthesouth

    cityofthesouth

    Jan 29, 2014
    I meant that the "rules of handle selection" often passed off as wisdom perpetuate regardless of these 100 year old conclusions which suggest otherwise. It's good information that if were sticky, would probably avoid a lot of pointless threads.

    ETA: "have nice day" is an FPSRussia reference.
     
  14. Square_peg

    Square_peg Gold Member Gold Member

    Feb 1, 2012
  15. 300Six

    300Six

    Aug 29, 2013
  16. Steve Tall

    Steve Tall

    Aug 28, 2010
    Thanks for that link. I like this notice from the USFS about the document:
    This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.

    Below is the text of it (might be a previous version, with transcription errors). First, a highlighted paragraph about what to look for if you're buying an axe handle:

    The man who is buying only one handle will usually
    find a visual method of judging hickory more convenient
    and practical than weighing. A fairly reliable visual
    guide to strength is found in the proportion of summer-
    wood appearing on the end of the piece. The summerwood
    is the solid-looking or less porous portion of each
    yearly growth ring. It is quite easy to distinguish
    from the springwood portion of the ring, which is full
    of pores or small holes. The summerwood has much greater
    strength than the springwood, because it contains more
    wood substance per unit volume. Wide bands of summer-
    wood and relatively narrow bands of springwood, there-
    fore, indicate a stronger piece of hickory than bands
    of summerwood and springwood of nearly the same width.
    The greater the proportion of summerwood in a tool
    handle or other piece of hickory, the greater will be
    its strength.



    FOREST PRODUCTS LABORATORY - U. 5. FOREST SERVICE - MADISON, WISCONSIN

    RED HICKORY AS STRONG AS WHITE HICKORY

    Usually only a small outer portion of a mature
    hickory tree contains white wood; the inner part, or
    heartwood, is red. Many people think that this red wood
    is not so strong or tough as the white wood. This belief,
    however, is discredited by actual strength tests made
    at the Forest Products Laboratory upon many specimens
    of red and white hickory. The tests show conclusively
    that, weight for weight, sound hickory has the same
    strength, toughness, and resistance to shock, regardless
    of whether it is red, white, or mixed red and white.
    The belief that white hickory is superior to red
    probably arose from the observation that young, rapid-
    growing hickory trees, which are nearly all sapwood,
    or white wood, generally have excellent strength properties.
    As the tree matures, however, this same sapwood
    is transformed into reddish heartwood; and a half-
    million tests made at the Forest Products Laboratory
    have failed to show any change in the strength of wood
    of any species, due to this natural change from sapwood
    into heartwood.

    A reliable indication of the strength of hickory
    is its density. That is to say, of two pieces of the
    same size and dryness, the heavier will be found to
    have the better strength properties. This fact makes
    it possible for large manufacturers or purchasers of
    hickory handles or wheel spokes to inspect the pieces
    by weight very rapidly and at small expense with auto-
    matic machinery.

    The man who is buying only one handle will usually
    find a visual method of judging hickory more convenient
    and practical than weighing. A fairly reliable visual
    guide to strength is found in the proportion of summer-
    wood appearing on the end of the piece. The summerwood
    is the solid-looking or less porous portion of each
    yearly growth ring. It is quite easy to distinguish
    from the springwood portion of the ring, which is full
    of pores or small holes. The summerwood has much greater
    strength than the springwood, because it contains more
    wood substance per unit volume. Wide bands of summer-
    wood and relatively narrow bands of springwood, there-
    fore, indicate a stronger piece of hickory than bands
    of summerwood and springwood of nearly the same width.
    The greater the proportion of summerwood in a tool
    handle or other piece of hickory, the greater will be
    its strength.

    The number of growth rings per inch also affords
    some means of grading hickory. Few growth rings per
    inch, as shown on the end of a handle, indicate a stronger
    and tougher piece than many rings, provided, of course,
    that it is straight-grained and free from defects at
    important points. Acceptable handles commonly show not
    more than 20 rings per inch, although much good hickory
    will be found with as many as 40 rings per inch. More
    careful inspection, however, by weight, is recommended
    for this very slow growth material.

    As a further guide in choosing a good tool handle,
    it is worthy of note that the best hickory shows an oily
    or glossy side-grain surface when smoothly finished;
    also, when it is dropped on end on a hard surface, such
    as a concrete floor, it emits a clear, ringing tone,
    in comparison with the dull sound produced by hickory
    of inferior quality.

    The adoption by the general public of these methods
    of grading hickory, in place of the worthless prejudice
    with respect to color, would put an end to the waste-
    ful practice of culling red hickory stock. When hickory
    was plentiful , this was a matter of seemingly little
    importance; but now every means should be taken to
    conserve the waning supply of an important wood, for
    which no satisfactory substitute has been found.
     
  17. 300Six

    300Six

    Aug 29, 2013
    Straight handled implements might not be so critical but I side with your stating that vertical grain is the only way to ensure there is no run out when dealing with curved axe handles. The curved shape is entirely in the horizontal plane and therefore would make any handle quite vulnerable to breakage (run out is unavoidable) if the grain were also horizontal.
     
  18. garry3

    garry3

    Sep 11, 2012
    It's pretty well known what to look for in the best hickory handle or perfect hickory handle. Despite how the goverment has tried to spin things in their publications.
     

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