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Hardness and Ease of Deburring
#1
Many thanks to Mike B. for the A2 blades - they keep us entertained with testing this weekend.
A2 tool steel is high carbon, high molybdenum.
The A2 blade #7 has been hardened to HRC 54, while the A2 blade #11 to HRC 62 - they represent extremes of the knife hardness range.
[Image: A2_blades.JPG]
This simple study is to compare how the blades differing only by hardness respond to deburring.
These two blades have been sharpened exactly the same way, and edge sharpness scores recorded through the process.

The results have come with no surprises: the harder steel is easier to deburr and get sharper.

The blades were bevelled at 15 dps on Tormek using CBN wheels, the edge set on CBN #1000 edge-leading.
Off the #1000 CBN wheel a tiny burr was visible.

[Image: A2_grinding.JPG]

Deburring was done on a paper wheel with 5 micron diamonds at the exact edge angle, i.e. 15 dps, with the help of our support for controlled-angle honing and computer software.
Finished on a paper wheel with 0.5 micron diamonds to see effect of burnishing.

5 microns correspond to JIS #3000, and 0.5 micron to # 30,000

[Image: A2_deburring.JPG]

In the context of this study, higher BESS numbers indicate a larger burr.

SHARPENING STEP - HRC54 - HRC62 (BESS sharpness score)
Off #1000 CBN - 197 BESS - 159 BESS

Paper Wheel with 5 micron diamonds at 15 dps
2 passes alternating sides - 193 BESS - 138 BESS
4 passes alternating sides - 187 BESS - 127 BESS
6 passes alternating sides - 127 BESS - 72 BESS

Paper Wheel with 0.5 micron diamonds at 15 dps
1 pass alternating sides - 321 BESS - 114 BESS     << burnishing effect - in the softer steel more metal gets displaced over the edge apex, forming a wire edge.

Paper Wheel with 0.5 micron diamonds at 15.4 dps i.e. higher-angle honing at 0.4 degree higher
1 pass alternating sides - 109 BESS - 95 BESS
final sharpness

That's it, only will have to update this post with sharpness scores taken in 24 hours to see if there is difference in the post-sharpening spontaneous dulling.
http://knifeGrinders.com.au
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Messages In This Thread
Hardness and Ease of Deburring - by KnifeGrinders - 08-18-2018, 04:44 AM
RE: Hardness and Ease of Deburring - by EOU - 08-18-2018, 10:24 AM
RE: Hardness and Ease of Deburring - by Bud - 08-18-2018, 08:15 PM
RE: Hardness and Ease of Deburring - by grepper - 08-18-2018, 10:38 PM

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