Part 2 that across my Facebook feed. Again, I can't find a link to share. So, since it has a 'Share' option, I'm thinking it is oke to copy/paste here.
Knife Sharpening Part 2
By: The Medical Survivalist
Facebook Llink: (if you have access)
https://www.facebook.com/themedicalsurvivalist/posts/250142962333204?__tn__=K-R
Morning Folks, today's Bushcraft related post is a follow up to my previous one about knife sharpening. Today we'll be looking at blade Grinds and the angles associated with such. Specifically we'll be looking at the Hollow, Flat, Sabre/Scandi, Chisel, Double Bevel/Compound Bevel, and Convex Grinds.
Hollow Grind—This is the type of grind where a convex hollow is removed from both sides of the edge. In doing so the result is a very sharp edge. However, being so thin the edge is more prone to rolling or damage than with other grinds. It's contraindicated for heavy chopping or cutting hard materials. A great example for this is your common razor blade, they have a hollow ground.
Flat Grind— With this type of grind the blade tapers all the way from the spine to the edge from both sides. Performing this grind will end up removing a lot of metal from the blade. Because there is so much metal removed during the sharpening process it's more difficult to grind. It sacrifices edge durability to achieve a higher level of sharpness.
Sabre/Scandi Grind— This type of Grind closely resembles the features of a flat ground blade. The major difference is that the bevel starts at about the middle of the blade as opposed to the spine. The Sabre/Scandi Grind produces a longer lasting edge at the expense of some cutting ability of the blade.
Chisel Grind—As on a chisel only one side is ground (often at an edge angle of about 20 – 30°) whilst the other remains flat all the way to the spine. Knives which are chisel ground come in left and right handed varieties, depending upon which side is ground.
Double/Compound bevel Grind— results with a back bevel, similar to a sabre or flat grind, put on the blade behind the edge bevel. This back bevel keeps the section of blade behind the edge thinner which improves cutting ability. With this grind the sharpness is sacrificed for resilience and as such is much less prone to chipping or rolling than a single bevel blade.
Convex Grind—doesn't taper with straight lines to the edge, the taper is curved, though in the opposite fashion to a hollow grind. This Blade shape keeps a lot of metal behind the edge making for a stronger edge while still allowing a good degree of sharpness. This is a common grind used on axes and is sometimes referred to as an axe grind. Convex blades typically need to be made from thicker stock than other blades.
Now that we have a working knowledge of Blade Grind types, let's look at the angles at which some cutting edges are sharpened at. We'll start low and end high when discussing these sharpening angels:
The lowest angles are reserved for edges that are typically cutting softer materials. These will typically be sharpened at an angle of 10 degrees or under. In these cases, the edges don't get as abused so the lower angle can be maintained without damage or failure. The lowest angles that we typically see are on straight edge razors. These are sharpened to an angle which is roughly 7 to 8 degrees. A straight razor has a fine and delicate edge that is very easy to damage.
Next up are those blades sharpened with an angle of 10-17 degrees. This edge is typically too weak for any knife that might be used in any type of chopping motion. Also consider that harder steels are also more susceptible to impact damage because they are more brittle. If your knife is used for cutting soft items or Field dressing game, this lower angle can hold up and provide a very smooth cutting action.
A 17 to 20 degree angle covers most kitchen knives. Most western knives are roughly 20 degrees and kitchen knives sharpened to 15 to 20 degrees cut very well and are still durable. These angles aren't incredibly durable as their total angle under 40 degrees.
With an angle of 22-30 degrees the knife edges are considerably more durable. A pocket knife or a hunting knife will inevitably see abuse not seen by knives meant for slicing or chopping softer materials. While the edge may not cut as well it will be considerably more durable.
Any edged tool or knife that is sharpened past 30 degrees will be very durable. Its cutting ability will be reduced But it has an advantage because more force can be used to make the cut. While the majority of knives won’t benefit from this sharpening angle, an edged tool like a machete, cleaver or axe that needs be durable are fine to sharpen in this angle range.
