|and toughness – a
good choice for these kinds of tasks. Once the knife is assembled, there
remains the task of defining the edge geometry and sharpening the blade.
Having received both Bill Carroll's completed knife and an unassembled
blade, I set about determining the bevel angles present on the blades in
order to see what needed to be done. With a laser pointer, a few tool room
fixtures and some patience I was able to build a setup to measure the bevel
angle from the reflection of the laser onto an angular degree scale (Fig.
1) and found it to be approximately 10º on each side or
a 20º included angle. This 20º bevel angle is somewhat acute; what this
knife needs is a bevel angle that will be sharp enough for skinning a hide
but also have enough steel behind the edge for durability between sharpening
sessions, something closer to 25º.
tool for this reshaping and sharpening task is the DMT Aligner guided sharpening
system. This system clamps the blade in a jaw with adjustable guide rods
that keep the sharpening stone at precisely the same angle across the entire
blade (Fig. 2).
Because this blade is exactly
1" wide, I set the Aligner adjustment rods in the fifth setting for a 24° bevel
angle. Since I will be reshaping the bevel, I chose to start with the DMT
coarse whetstone (blue). Marking the bevel edge with a felt-tipped marker
will let me know when I have fully reshaped the bevel angle without over-sharpening
and wasting the blade life (Fig. 3).
Progressing through to the fine stone (red) and finally the extra-fine
stone (green) while using the marker trick at each step allowed for a very
quick and accurate bevel reshaping. Using the same setup each time the
blade needs a touch-up is easy; just a few strokes with the fine or extra-fine
DMT diamond whetstone and the blade is back in shape. For those who already
have a whetstone. but perhaps not the Aligner system, the same task can
be done with some skill and a couple of quarters!
place two stacked quarters on the corner of your for the
same setting as was used for the Aligner with a 1"-wide blade (Fig.
4). Stroke from the heel of the knife to the tip, into
the cutting edge while locking your wrist to maintain that same bevel angle.
Do about six or seven strokes on one side, then flip the knife over while
moving the two quarters to the opposite side of the stone and repeat the
same motion for the other bevel. Step to the next fi ner grit if you have
it and repeat the same sequence for a very sharp and durable edge.
—Stan Watson is technical director for Diamond Machine
Technologies and is responsible for new product innovation and engineering
processes. He holds nine DMT patents.