Edge Retention : Hemp

Basic methodology :

edge bevel at 4-8 dps
micro-bevel at 24-26 dps, 6 micron DMT MXF (25 micron)
slicing cut made through 2" of straight section of blade
sharpness is the edge length required to cut a cord under tension
cut speed is approximately 1 ips

In addition :

edges are checked under 50X mag before and after use
edge are reset (destressed) before sharpening
bevel before micro is set with a 700-1000 grit stone (10-15 micron)

Hemp details :

one lay of 1/2" hemp
random sampled
population has minimum 100:1 ratio over sample size
checked on a standard blade to ensure no long term drifting

In regards to the values :

5.0^-0.1(0.4)

means :

5.0 is the median performance
-0.1 is the change that the last run made to the median
0.4 is the standard deviation

As a rough check, as long as the runs are changing the median by more than the standard deviations it is unlikely the result is stable (i.e. the true value).

The full table showing the results of each knife. Note the color codes :

damaged steel/heat treat issues
edge instability / excessive carbide volume

Edge retention on 3/8" hemp at 15, 10 and 5% of optimal sharpness
Knife	Steel	Hardness	# runs	Sharpness	15%	10%	5%	Sharpening
Knife	Steel	Hardness	# runs	Sharpness	hemp cut (#)			# passes
small Peasant	L6	54-56 HRC	4	67⁺¹⁷(30)	3.7^-0.0(0.8)	6.5^-0.4(1.4)	16^{- 1}( 4)	150^-50( 66)
Opinel	1084	54-56	4	68^{- 1}(16)	3.8^+0.3(0.6)	6.6^+0.5(1.2)	16^{+ 1}( 3)	150^-25(384)
Uddo Puukko	O1	58-59	5	63^{- 2}(12)	12.8^+0.6(2.9)	21.5^+0.2(5.1)	48^{- 3}(13)	475^-175(135)
Lum	VG-10	58-60	5	56^{+ 5}(17)	13.5^-1.5(1.6)	23.4^-2.5(3.0)	54^{- 4}( 8)	150^-0( 23)
cKc micro-hiker (B)	AEBL	61-62	3	95^{- 0}(40)	9.9^-4.0(1.8)	17.8^-6.4(3.5)	45^-13(10)	153^-20( 30)
cKc Slipjoint	Elmax	60	3	67⁺²²(24)	13.4^+2.0(2.0)	27.0^+2.6(4.4)	81^{+ 5}(15)	150^{- 0}( 13)
Coyote Meadow	CPM-10V	62.5	4	71^{+ 0}(33)	12.8^-0.1(2.6)	22.5^-0.8(4.8)	55^{- 4}(13)	975^-25(1019)
Farid	121 REX	68-70	3	59^{+ 9}(12)	6.3^-1.4(0.9)	11.7^-1.9(1.7)	30^{- 2}( 5)	1000^-250(686)

Comments and references

Comments can be emailed to Intro : Hemp cutting (T0.1M)

Lum Chinese Hemp Cutting (Spyderco forum)

Most of the pictures in the above are in the edge retention album at PhotoBucket.

Last updated :	16/09/2013
Originally written:	11:29:2011