World's greatest sharpener


Introduction

The page collects the results of individuals sharpening OLFA blades so as to maximize sharpness which is measured both on the push cutting cutting thread and sliced by drawing across light cord1 To participate send an email. There is no restriction on sharpening method. The blades are also used for a number of semi-standard checks for sharpness which are somewhat subjective such as; whittle hair (take a free standing hair and slice it along its length without cutting through it), cut hair backwards above the skin, slice and push cut newsprint, paper towel, and toilet paper. The cuts are also done perpendicular to the paper and cutting means there is no ripping or fraying. Push cutting means no draw.

There are four possible rankings;

If a blade can do a push cut it can slice, and a push cut rank of - is higher than a slice rank of +. Each blade is hyperlinked to a description about the sharpening method used as well as a brief commentary on the subjective tests.

Results to date

First the blades are checked for sharpness, the thread and light cotton cutting (100 grams of tension) were averaged along the entire edge, for the subjective ranks, the blades average performance was used :

initial sharpness : performance noted for best blade

Namethread cotton total whittle hair catch hair newsprint papertowel toilet paper
grams millimeters
Ben Dale  71.2 (3.4) 57.1 (3.9) 128.3 (7.3) +Y push : +push : Nslice : Y
David Rishar  57.9 (3.0) 99.6 (5.9) 157.6 (8.9) +Y push : +slice : Yslice : N
Ray Kirk  83.6 (2.8) - - Y- push : +slice : Yslice : -
Warren Higgins 141 (26)200 (17) 341 (43) N- push : Yslice : Yslice : -

The numbers in brackets indicate the spread of the results, specifically it is the standard deviation in the mean. This is just a fancy way of stating that the performance was mainly from the average plus or minus two times the spread. For example Ben's result of 71.2 (3.4) means that most of the measurements (95% specifically) fall within 64 and 78 grams. Thus the smaller the number in the brackets the more consistent the sharpness along the edge.

To determine the cutting ability the blade was drawn through a piece of 3/8" hemp for a slice through five sections of the blade. A push cut was then performed on the remaining three sections. In both cases the cutting was performed on a scale and the force recorded. Since this is just one cut, the random nature of the hemp can not be minimized and the section being cut is always made from the same roll and a non-knotty section is chosen visually. The performance here reflects both the initial sharpness and the edge angle :

cutting ability on 3/8" hemp : performance noted for best blade

Name slice push total
force in pounds
Ben Dale 4 12 16
David Rishar 6 12 18
Ray Kirk 13 13 26
Warren Higgins 10 20 30

Finally, the blades were checked for edge retention by cutting 128 pieces of 3/8" hemp on a draw through five sections of edge and 64 push cuts through two sections of edge. During the cutting, a minimum of 12 rolls of hemp were used and cuts made from them equally to smooth out the variance from individual rolls of hemp. The slicing aggression was measured by cutting light cotton under tension and the edge alignment checked by push cutting light thread. The performance on the hemp was also recorded for the last cut on the same roll as used to measure the cutting ability in the previous table :

edge retention : performance noted for best blade

Name slice push
200 g 500 g hemp thread hemp
Ben Dale 2.9 (2) 0.46 (7)  7 210 (10) 22
David Rishar 9.5 (5) 0.5 (1) 11 170 (21) 16
Ray Kirk       187 ( 5) 25
Warren Higgins 4.3 (2) 0.7 (1) 12 239 (31) 26

In terms of defining who has the record, the thread and cotton performance is used, the hemp numbers are for perspective, but highly variable as since they are only one cut, they are influenced by the random nature of the hemp in that particular region cut.

Present Champions

NameDate of recordcatagory
David Rishar 09 : 07 : 2005Initial Sharpness : Push
Ben Dale 08 : 10 : 2005Initial Sharpness : Total
Ben Dale 08 : 10 : 2005Initial Sharpness : Slice
Ben Dale 08 : 10 : 2005Edge Retention : Slice
David Rishar 09 : 07 : 2005Edge Retention : Push
Ben Dale 08 : 10 : 2005Cutting Ability : slice
Ben Dale/David Rishar 08 : 10 : 2005 / 09 : 07 : 2005Cutting Ability : push
Ben Dale 08 : 10 : 2005Cutting Ability : Total

To not forget :

Past Champions

NameReigncatagory
Ben Dale 08 : 10 : 2005 - 09 : 07 : 2005Initial Sharpness : Push
Ben Dale 08 : 10 : 2005 - 09 : 07 : 2005Edge Retention : Push

References

name1 : Cliff Stamp, cutleryscience.com, 2006.


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Written: Aug. 2005 Updated: Aug. 2007 Copyright (c) 2005 - 2007 : Cliff Stamp