Home Misc Different Grinds and the Use of a Hollow Grinding Jig

Different Grinds and the Use of a Hollow Grinding Jig


Sharpening a knife will require proper grinding equipment to achieve a smoothly surfaced blade. The edges of knives are shaped differently one from another.  Some are tapered to the cutting edge on both sides of the blade, while others only on one side, etc.  These different shapes are called grinds. This article will discuss the different types of grinds as well as details on the hollow grind jig.

Types of Grinds

The following typical grinds are as follows:

Wolverine Grinding System with VARI-GRIND jig
  • Hollow Grind – a knife blade with a hollow grind appears with a beveled cutting edge and characteristic concave. These are better known as straight razors common for shaving objects. They are moderately sharp but needs stropping on occasion.
  • Flat Grind – a flat grind knife has only a single bevel with both edges sharpened all the way from the spine to the tip. Most knife sharpening systems do flat grins easily.
  • Chisel Grind – only one side of the blade is ground while the other is flat. Regular kitchen knives are chisel ground, perfect for efficient cutting or slicing.
  • Convex Grind – the tapering of the blade is curved rather than straight. It is also known as an ax grind due to the fact that axes are ground in this way and hardly any other way.
  • Sabre Grind – almost similar to a flat grind, the middle part is the beginning point of the blade rather than the spine. Tactical knives and kitchen knives are ground in this way for a more lasting edge.

A Reliable Grinding Jig

Jigs are objects placed at the end of a grinding stone in order to keep a blade or object to be ground in place. They can be crafted from wood or steel. Sharpening jigs are common in knife making as the styling of blades requires a steady motion. Not all makers have the ability to precisely shape knife edges without the aid of a jig of some sort. Among the most common grinds that need jigs is the hollow grind.

A hollow grinding jig must be able to hold the blade in place on a hundred and eighty-degree angle. Simply put, a jig must hold an object straightly to make sure that each end is level to each other. Jigs that are collapsible and easily foldable are not recommended. Constant adjustment is required with such jigs; each time they are folded and unfolded its surface’s alignment is changed. Sharpening to the jig must first be done before sharpening a blade.

Hollow Grinding Jigs

Making knives with hollow grind jigs is fun.
Making knives with hollow grind jigs is fun.

Hollow grinding jigs are helpful for removing rusted surfaces of a steel blade. With the help of a hollow grinding jig, the steel blade can be rid of burrs or rough patches without overlapping. A jig is useful mostly for flat ground and saber ground knives. The steel knife or blade will have better grinding if it is stable. It will have less noticeable marks unlike that of unleveled grinding. A hollow grinding jig will efficiently help knife makers achieve equally angled sides of the beveled blade.

Advantages and Disadvantages

There is, however, no one hundred percent guarantee that a jig will be in the same position or alignment as before. This fact causes difficulty in achieving the perfectly same ground edge as a preceding model. Hollow grinding jigs are not as flexible as opposed to handheld. For styling ax grinds and chisel grinds, a maker will have difficulty in maneuvering the blade in the proper angle if it is attached to a jig.

A jig is meant to keep an object in place while being ground in order to create a perfect edge. Styled or differently ground blades cannot be moved in the supposed motion under a jig. No other grinding method can be done if the machine is equipped with a hollow grinding jig. It can only be of good service when hollow grinding. If other grinds are expected to perform well, the jig must either be removed or replaced with a different one.

Other types of sharpening jigs may provide better maneuverability but all will keep the blade at a restricted motion. Professional knife makers can grind steel blades without the help of a hollow grinding jig and still achieve their desired edge. Depending on the preference of workability, hollow grinding jigs can make making knives easier. Check out KnifeUp’s machete, tactical folding knife, and butterfly trainer review.


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