Experiments on Knife Sharpening John D. Verhoeven ... - BushcraftUK

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Figure 44 presents the micrographs for Blade AP-3. Its preparation differed fromAP-1 in that the final belt was much coarser, 700 vs. 2000 grit, and the buffing wheel wasfelt rather than cloth. Comparing Figs. 44 to 43 it is seen that the face of the blades havebeen polished to about the same level. Hence it appears that the felt wheel buff haseffectively removed the coarser abrasion marks that must have been produced by the 700grit belt used with the AP-3 blade. However, the bur produced with the felt wheel is moredominant, displaying a large fold-over bur on the down face view, which is wellillustrated in the Down face micrograph of Fig. 44 and at the top right of the Edge viewmicrograph.The stropping experiment on clean leather employed a flat leather strop attachedto a board. The experiment was similar to that of section [4], p. 19, except that it wasdone by A. Pendray in his shop, rather than by the author in his lab. As in section [4]study, it was found that the stropping operation on clean leather had little effect on thesurface smoothness or bur geometry. To save file space micrographs of blades AP-2 arenot presented. Their appearance was very similar to Figs. 43, with the addition of someminor sized scratches produced by the stropping operation.Conclusions1 These results suggest that buffing on cloth or felt wheels is not the best method forfinish sharpening of knife blades. It appears that even a light buffing action removes asignificant amount of metal near the thin edge of the blades which leads to a bur alongthe edge that is consistently larger than the bur formed with leather strops or wheels.However, a single experiment with a two step buffing operation, first with a coarsecompound and then a fine compound, did produce improved results and further study ofthat method may indicate that it is equivalent to the final polishing on leather media.2 The experiment with stropping clean leather confirms the previous experiments. Thenatural abrasives present on clean leather are not adequate to remove edge burs or surfaceabrasion grooves on stropping.36
[7] <strong>Experiments</strong> on carbon steelsA series of experiments was done on the carbon steel blades having the geometryshown in Fig. 6 and the composition and hardness shown in Table 2. The main purposeof this study was to evaluate the effect of reducing the hardness of the steels from theHRC = 60 level to the HRC = 40 level. The conventional steels, 52100 and 1086, wereheat treated to final hardness of Table 2 by quench and tempering treatments. TheDamascus steel was a 1.6 % carbon steel of the genuine Damascus type [6] that was oilquenched from below it’s A cm temperature to produce the HRC 40 hardness value. It wasa pearlitic steel, while the other steels were quenched and tempered martensitic steels.<strong>Experiments</strong> with the TruHone machineThese experiments utilizedthe 1000 grit wheels of the TruHone machine for the final grinding after an initial grindwith the 600 grit wheels. The initial experiments were done with a 2β edge angle of 38degrees using the same procedure as used with the stainless steel blades discussed onpage 8 except that the 2β edge angles on both the 600 and 1000 grit wheels wasdecreased by 3 degrees. Figure 45 presents face views of three steels with HRC varyingfrom 40 to 60. The results show that at the reduced hardness of HRC = 40 there is adefinite increase in the degree of edge roughness.These carbon steel blades were used in the study with the TruHone machineaimed at reducing the 2β edge angle to the minimum possible values. The initialexperiments were done at 2β value of 20 degrees. At this small angle the operator couldfeel a definite vertical pulsating motion as the blades passed over the wheels. At 20degrees the wheels of the TruHone machine used here had a very small overlap. Hence,any out-of-round wheel shape leads to a significant up-and-down pulsating motion as theedge of the blade passes over the wheels. This action produces edges that are notstraight. It was concluded that a 2β edge angle of 20 degrees was too small for goodsharpening, and a series of blades were done at what seemed to be the smallest angle37
Page 1 and 2: Experiments on Kni
Page 4 and 5: as a guide to good sharpening techn
Page 6 and 7: machine ground. The final 2β edge
Page 8: [2] Experiments wi
Page 11 and 12: Even on freshly dressed wheels a 2
Page 13 and 14: ledges of material has broken out o
Page 15 and 16: at the 2β edge angles of 50 and 70
Page 17 and 18: 7 All of the blades that were studi
Page 19 and 20: Japanese waterstones plus leather s
Page 21 and 22: Figs. 23-24. The blade of Fig. 25 w
Page 23 and 24: Figs 23 to 26. It appears that the
Page 25 and 26: [5] Experiments wi
Page 27 and 28: the 2β target hone angle set to ar
Page 29 and 30: lade of Fig. 33 along part of the l
Page 31 and 32: 3 Dropping the 2β edge angle from
Page 33 and 34: the 600 grit wheels were largely re
Page 35: seen that the buffing action is rem
Page 39 and 40: found that the softer steel produce
Page 41 and 42: optimum EW values found for afinal
Page 43 and 44: [9] Summary and ConclusionsThese ex
Page 45 and 46: 6 When the 2β edge angle is reduce
Page 47 and 48: Appendix 1Edge angle measurements w
Page 49 and 50: β = arc cosine((R 2 +L 2 -Y 2 -h 2
Page 51 and 52: YY = 45.5 mmLThese parameters can b
Page 53 and 54: Appendix 3The Tru Hone Sharpening M
Page 55: To overcome this problem withgrindi

Experiments on Knife Sharpening John D. Verhoeven ... - BushcraftUK

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