It's complex
-Historically the grinds were left up the smiths to interpret as they desired for the tasks stated in the options description. We found though that this was differing between smiths and blades a fair bit though and wanted to make sure that there was a bit more consistency in the ways these options performed.
-Around the start of 2023 we moved to standardise the geometry a bit more. This is tricky as the standard measures of geometry (edge angle, edge thickness, grind angle) don't really match up well to the full convex grinds and at times complex upper grinds that we do. Furthermore freehand grinding with wheels makes it hard to implement any formalisations of grinds while actually grinding them. Instead we moved to using laser cut 3d gauges that I whipped up in CAD. The blades can be dropped into these gauges and depending on how the light shines through the sides it lets you know if the edge geometry needs to be made thinner or has been ground too thin etc. Through my CAD files I can produce a dimension for the apex angle of these various grinds. However in reality this angle doesn't really exist. It's the imagined tangent angle where two arc meet. It isn't something that's feasible for us to verify on actual blades or reproduce with a good deal of confidence or consistency. These profile gauges help us to hit the silhouette for the general edge shape decently which is a big upgrade for consistency.
-In the last year though we found that our work to control and refine edge geometry was in many cases being overshadowed by the impacts of the geometry above it. For example we could produce a mutiny and a panawal with the same performance grind silhouette at the edge. The mutiny would cut very well but the taller/thicker upper bevel or upper grind would add a level of cutting resistance to the panawal which stopped it from matching up to the performance expected of a performance grind.
What to do? We could expand the scope of what a performance grind means (blended bevel, restrict thickness of upper grind) but this would mean that some of these blades would look radically different to the usual versions- particularly a problem on traditional and historical blades which would be the ones mostly impacted by these changes. It would also make it hard to write descriptions for the blades. A panawal is a big beefy blade, but with a performance grind it's not anymore? How do you communicate an understanding of these technical details to a customer? We're already putting a lot of complexity and info load on our customers.
Instead we decided to trim the options that fitted least from all the blades. HD not available on some of our leanest, slipperiest blades (that aren't really built for it in the spine and upper grind) and performance not available on our chunkiest monkeys. Keeps things simple for the customer and it also helps to focus our blades a bit which in a way makes the whole lineup more diverse. Not everything is a do everything blade that can be made however you want- there are some blades that exist at the extremes and carve our their own performance niches. In future maybe we'll pivot and handle things differently- maybe we'll scrap the whole thing and just give certain blades certain warranty levels innately.
---------------------------------------------------------------------------------------------------------------------------------------------
C
Chandra
These blades were ordered a few years apart- with the right long knife being when we were in our earlier days of manufacturing. In that period of time patterns had a tendency to be interpreted a little loosely and would often drift a touch as new sheet metal patterns were traced from older ones. Running changes were also made by smiths that weren't picked up on and sometimes they would continue making it in this way for a period of time- like this plunge line.
The left blade is how they've consistently been made for some time now and is generally more accurate to the pattern, including the plunge line.
I think the micarta in the picture is not custom but just what our forest camo looked like in full tang at this time- we have swapped between a few fabrics due to lack of availability over the years.
Take care,
Andrew and the team at Kailash