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Marking Knives |
Edge Angles
Guidelines shown below are for Included Angles (α).
Single Angle Blade
Japanese marking knives are typically sharpened only one side (as depicted in the picture to the left). For those,
α = β
A knife is only as good as the one who wields it.
Patrick Ness
The Projection Calculator is available for calculating setup for Tormek knife jigs. This one is web-based and does not require Excel.) CB's USB Projection Calculator is also available for calculating setup for Tormek knife jigs.
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General Guidelines |
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| α |
Point Angle |
Notes |
| 25° | 120° |
The Tormek KJ-45 or SVM-45 Knife Jigs work well for these, and the Tormek SVM-00 Small Knife Holder may be needed, depending on the blade and the blade's handle. Note: In the Tormek video. Part 18: Sharpen rare and specialized tools, the use of the side of the stone is recommended. To do this, the SVD-186-R and MB-100 are used. |
When looking at the blade from the side, generally it has a 120° angle. Some choose to round off the pointed tip.
Even if that is not done, setting a small nose radius of 0.007 in. (0.2 mm) is a good idea. If it is too pointy, the blade's tip can rip at the wood fibers.
The shape of the grind used is a call best made by the tool's use, based on their own experience. Additional notes are available on separate web pages for:
A micro bevel is not usually added to this tool as the sharpened surface area is so small that this is not needed to make re-sharpening easier and faster.
Notes are also available on a different web page for Micro / Secondary Bevels.
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Click on either image for a bigger sized view.
Images courtesy Todd Simpson via Dr. Vadim Kraichuk of KnifeGrinders.
The scanning electron microscope (SEM) images to the right show the burr on a knife in the 1st image, that was then "ripped off" by cutting cross-grain into a piece of redwood in the 2nd image - loss of the sharp edge is obvious.
Key take-away from these photos : don't skip the honing step.
