Standards
A 6, 15
B 1, 3
C 3
D 1, 3
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Concepts
F = MA
Inertia
Friction
Surface area
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Anyone who has tried to make a hole in the ice with an axe knows
the importance of an ice pick. People have always needed water from
creeks, rivers, and lakes. They have always needed to set fishtraps,
nets, and snares under the ice. They have chopped sled trails across
ocean ice packs. Oldtimers used an icepick to cross thin ice, picking
and listening to the sound of the ice.
Years ago, the Department of Fish and Game insisted that beavers
be trapped and snared in the winter rather than shooting them in
the spring as they always had been. This forced people to pick through
many feet of ice in order to set the beaver snares. This was not
a traditional method of trapping. Ice pick design became an art
of greater importance.
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Weight
The
weight and shape of the ice pick make a tremendous difference in
the operation.
If an ice pick is too heavy, it will quickly tire the individual
lifting and driving the pick into the ice. (If the ice pick is too
light it will not have enough force to shatter the ice.) Force z
mass x acceleration. The greater the mass, the greater the force.
The person will have to use the strength of his arms instead of
the force of the heavier pick.
A larger and stronger person will prefer a heavier ice pick.
Shape
The shape of the tip is most important. If the edge is too thick,
it will not penetrate the ice.
If the edge is too thin, the pick will penetrate the ice well,
shattering the ice around it. However, it will dull quite easily
if it hits rocks in the ice or the creek bottom. Every beaver trapper
has picked through several feet of ice and hit gravel rather than
water!
If the icepick were sharpened on both sides, it would be impossible
to widen the sides of the hole. The ice pick would glance off the
side. The shape of the tip is critical.
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Slight
Bend
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A Secret
One secret that really sets an exceptional ice pick apart from
others is almost unnoticeable. The tip has a slight bend toward
the flat side.
If the ice pick is straight, it will penetrate the ice, chopping
well. But if there is a slight bend, the tip quivers when it penetrates,
shattering much more ice than a straight one could. Ice picks with
different designs sound different when they pick the ice.
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Width
The width of the tip is also important. If it is too wide, it
will have too much surface area to penetrate the ice. If it is too
narrow, it will not effectively cut sticks that are embedded in
the ice. This is particularly important around a beaver feed pile.
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Knob and string
on handle
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Handle
If
the handle is too smooth, it will slip out of the persons
hands, lost down the hole. If it is too rough, there will be adequate
friction to grip, but it will make the persons hands sore.
Many people put a knob on the top to keep it from slipping through
icy gloves. Others tie the pick to their arm. Many trapping opportunities
have come to a quick end when the icy handle slipped through icy
gloves and plunged into the dark water.
If the handle is made of steel or aluminum, it will be too cold
to grip and will collect so much ice it will be far too heavy. Wooden
handles are best. Spruce is the choice material for the handle.
It is strong and resists rotting. Although birch is strong, it easily
rots.
The
steel bar is often inset and bolted to the wooden handle. The nose
of the wood is rounded to reduce splashing. Getting the hole down
to water isnt hard. Once the hole fills with water, it is
hard to make it wide at the bottom.
If the bottom of the hole is too small, the hole will freeze over
quickly for lack of current.
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Quality Steel
The steel of a nail bar is of high quality. Some people use spring
steel from a snowmachine. Others use the drive shaft from a snowmachine,
or car axle. Others use a wrecking bar. Hit the steel with another
piece of metal. If it has a clear ring, it probably is good steel.
If it sounds dead, it is probably not good steel.
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Commercial Ice Picks
There is a commercial ice pick available that looks like this.
I havent tried one, so am not qualified to comment, although
I have heard good stories about them.
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Insights
No one wants to pick more ice than is necessary. Some people return
to their beaver set once the hole is skimmed over with ice, and
cover it with snow to insulate it from freezing further. In severely
cold weather, one fellow allowed the hole to freeze over, then poked
a little hole with his knife. He blew into the little hole, leaving
an insulating bubble of air between the water and ice, sealed the
hole with his tongue, and covered the skim of ice with snow. The
next day he had very little ice picking to do, while other trappers
spent hours opening the holes again.
These are cold weather techniques.
The art of making an ice pick is almost lost. City water, new
technology and low prices for beaver pelts have nearly made ice
picking a thing of the past. Many people now use ice augers, both
manual and motor driven. Ice augers work well to make holes for
fishing but, for many applications, the holes are too small.
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Activities
- Make an ice pick out of a wrecking bar or other good steel.
Before putting a slight bend in the tip, make a few holes in the
ice. Then put the slight bend. Observe the difference. Does it
widen the hole better with the bend? Can you hear the difference
between the two picks?
- Before rounding the nose of the wood on the handle, leave the
wood square. Does it splash once there is water in the hole? Round
the nose of the wood and try it again. Does it splash as much?
- Strap a five to six pound weight to the ice pick you have made.
Pick a hole. What differences do you observe? (Ankle or wrist
weights might work well.)
- Try to make a hole in the ice with an axe. What is your experience
once the hole fills with water? Can you widen the bottom of the
hole?
- If there is an ice auger in the village, compare the time and
effort required to make a hole with the auger to the time it takes
to make a similar hole with an ice pick. Which is faster and easier
for you? What are the advantages of each?
- Observe how icy your gloves get when using the ice pick. What
will you do to increase friction so you dont lose the ice
pick down the hole?
- Listen closely. Can you hear the difference in the sound of
the ice just before you punch through and water comes into the
hole?
- Make an ice pick out of a snowmachine spring over 2 wide.
What differences do you see between this ice pick and the first
one.
- Compare the ice pick you have made with a commercially designed
ice pick if there is one available. If they are both sharp, which
one works better for you?
- Are there any homemade ice picks in the village? Look at them.
What do the tips look like? How wide are they? How heavy are they?
What is the average weight? What kind of steel are they made of?
Do they ring when struck with another piece of steel? (The wooden
handle will deaden the sound to some degree.)
- What kind of wood is used for the homemade ice pick handles?
- Talk with the local beaver trappers and, if possible, go out
trapping with them. When you get back, describe to someone else
what you learned.
- By inquiry in the village, discover the difference between
an ice pick used for walking after freeze-up and one used for
beaver trapping.
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Student Response
- Why is it important to have an ice pick that has enough mass?
- Draw an edge that is too thick. Draw one that is too thin.
- Why is a slight bend put in the tip of some ice picks?
- Why is friction important on the handle?
- What is the most common material for an ice pick handle and
why?
- What happens if the bottom of a water hole isnt widened?
- Draw a good ice pick, including handle. Identify the parts.
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Math
- Mike has a chance to go beaver trapping with his uncle. A gasoline-driven
ice auger costs $209. He can make his own ice pick for $12. If
the average price of a beaver pelt is $25, how many beaver does
he have to catch to break even with the cost of the gasoline driven
auger?
- Mike can pick 14 holes a day when the ice is 3 thick.
The next year he traps, he finds that the ice is 4 thick.
Approximately how many holes will he make if he picks at the same
rate?
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