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A Friction Fire Inquiry: Hand Drill
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| I can think of no other stone age skill that
satisfies and intrigues me as much as the hand drill method of friction
fire. Since learning about it two years ago, I have been consumed by its
delicate intricacies, temperamental nature, and its sheer power to transform
physical prowess into self-reliance. What an absolute miracle it is to start
with twigs and branches (or roots or shelf fungi!), add refined kinesthetic
form and determination, and be able to coax not only the essence of
combustion out of a seemingly inert material but finally one of the most
important catalytic tools humankind has ever harnessed! Hand drill can
provide an exacting metaphor for the span of human life—from the obvious
anatomical symbolism of human union between the genders to the birth of a
spirit in need of nourishment and encouragement in order for it to be
sustained and grow into a breathing and consuming (and perhaps sentient, for
it seems to be drawn toward its needs) entity, distinct from its genesis. In order to better understand this
evolution from friction to fire, I gathered spindles from 52 native
and 22 non-native species of trees, shrubs, forbs, and lianas (plus
one grass) and applied them via hand-powered rotational friction to
four species of hearthboards (clematis, two redwood pieces of
different densities, CA buckeye, big-leaf maple). There were many
aspects to the nuances of hand drill that I was curious about, and
my results are outlined below. Throughout these experiments I took
care to adhere to the technological parameters afforded by the
paleolithic and mesolithic standards that I aspire to emulate—no
metal implements were used. |
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| The Baseline Data Table 1 displays
the successes and failures I incurred trying to attain an ember with each of
the 370 possible wood combinations. I also offer a very subjective effort
rating for each attempt, with a 1 representing a low expenditure of energy
(around a minute or less in duration), a 2 corresponding roughly to a two
minute endeavor, while a score of 3 defined what felt like an average effort
(three to four minutes). A 4 was given to a successful attempt that took
longer than around four minutes and required multiple sockets (having burned
through the first one). I assigned a 5 to failed ember attempts. The fifteen woods that proved easiest
to use as spindle materials are: yarrow, horseweed, box elder, CA
buckeye, mule fat, blue elderberry, coast redwood, cattail, big-leaf
maple, mugwort, bull thistle, scotch broom, Douglas fir, CA figwort
and sow thistle. |
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| Wanting to somehow check the accuracy of this
effort rating system, I calculated the average effort for all attempts
(4.0). By definition, this number should have been much closer to my
arbitrary average rating of 3. A previous, similar bow drill exploration of
1,946 wood combinations gave me
an average of 3.2 from all effort ratings—a figure that exhibits a more
consistent estimation of effort comparison. This tells me that, since hand
drill is generally more difficult than bow drill, I tend to misjudge the
relative ease and difficulty of hand drill attempts more than with bow
drill. The Role of Wood Density
Given my interest in the discussion of the merits in having a softer
spindle versus a softer hearthboard, which has been entertained in some
primitive skills publications, in Table 2 you will see my measurements of
the specific gravity, or density relative to that of water, of all the
woods. The paucity of relative density data for our tree species in
California caused me to measure it myself as follows:
Measuring Relative Density
- Fill a tall, narrow vessel with water (bucket, graduated cylinder,
capped PVC pipe).
- Slowly submerge your spindle or hearth board until it begins to
float. I like to dip the non-working end (the tip of the spindle that
doesn’t end up in the hearth board’s socket) first—there’s something
counter-intuitive about purposefully dunking your fire sticks
underwater. You want to notice where the floating water line is, so
don’t let your wood bounce into the water. You can mark the water line
with a pencil—otherwise you can see the boundary between wet and dry
wood.
- Measure the length of the portion of your wood specimen that was
underwater and divide that into the total length of the wood to get a
percentage. If the piece of wood totally submerges under the water, then
it is denser than water (Lignum vitae, a vine found in Florida, does
this) and will result in a specific gravity of over 1.0. Most woods will
only partially submerge, giving you a fraction under 1.0. The number you
get, in of itself, is not important. It is only when you compare two
findings, such as poison hemlock’s 0.14 specific gravity against
snowberry’s 0.90, that you can derive some meaning (the latter is six
times denser than the former). Please note that every species of wood,
even from the same tree or even the same branch, can vary in its
density.
It is interesting to observe that the aforementioned fifteen best spindle
woods have an average density of 0.42. Compared with an average density of
0.53 for all spindle woods, one could suggest that using softer spindles can
increase your chance for success (but keep in mind that I’m not a
statistician and offer only anecdotal supposition). Further support for this
theory comes from evaluating spindle performances on the two redwood
hearthboards of different densities. On the softer redwood board, the
lighter 50% of the spindles performed better (3.32 average effort) than the
denser 50% (4.36 average effort). On the harder redwood board, the lighter
50% of the spindles also performed better (3.46 average effort) than the
denser 50% (4.32 average effort). This may indicate that it is more
advantageous to use a softer wood for your spindle, irregardless of the
density of your hearthboard. It makes sense that difficulty would arise when
trying to use denser wood combinations in general (but we already knew that,
didn’t we!).
Green vs. Dead vs. Nascent Growth
A friend of mine once noted that nascent growth (otherwise known as
sucker sprouts, stump sprouts, adventitious growth) spindles seemed to work
better than wood from regular branches. I like nascent growth for its
straight form, as seen with big-leaf maple, CA buckeye, CA Bay, and other
softer hardwoods. Table 3 shows my efforts comparing the use of nascent
growth, green-cut and dead-cut spindles on CA buckeye and redwood
hearthboards. The limited data doesn’t support the advantage of nascent
growth but does show the value of collecting dead wood for use as spindles.
Non-Notched Hand Drill Embers
Finally, I tried my hand at producing hand drill embers without
carving the notch into the socket. I wanted to see if I could take a
step out of the process in order to make it easier. Table 4
illustrates that I was able to produce an ember only 28% of the
time, which re-enforces the value of the notch (unless a person
sticks to those woods that generated embers). |
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| I hope that this endeavor proves useful to
you. I encourage you to experiment with your local woods and share your
findings. I hear some people are compiling a national database of good
friction fire woods—please feel free to add this data. |
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NOTE: To view the data tables please see the
PDF of this
article, or click the below links
to JPG files:
- Table 1: Hand Drill
Effort ratings
- Table 2: Specific
Gravity for Hand Drills
- Table 3: Specific
Gravity for Hearthboards
- Table 4: Green vs
Dead vs Nascent Growth Spindles
- Table 5: Effort
Averages
- Table 6: Non-notched
Handdrill Embers
- Table 7: Specific
Gravity of Hearthboards
- Table 8: Specific
Gravity for Hand Drills - measured myself
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