Structural Edge Testing of the Extrema Ratio Satre N690 and S600 blades

[@marcinos303]

Great material! I have just purchased a Satre version with the Bohler S600. There is an opinion that these are knives for cutting meat and planing wood rather than for cutting cardboard (thick blade), but I couldn't resist the design. This will be my first knife from the ER. I wonder if the heat treatment is actually done on the 64 HRC. Greetings from Poland😉

[@RSLtreecare]

Very interesting. I have seen this before. It's very detailed, what's the conclusion? Are these good working survival tools.

[@Flockingtheherd]

Just an fyi your using way too much pressure when stropping which is causing you to round over your edge. Use light pressure and keep it at the same angle cus you were a bit all over the place on those edges. It’s a strop not a grind stone :p also extrema ratio uses a rather unique convex edge, it’s a very aggressive and steep edge, great for cutting things like flesh but terrible for cutting things like paper lol. Many people despise extrema ratio because they don’t perform like current market knives, which are generally created for cutting sheets of paper in mums basement lol. Extrema ratio makes if not the highest quality knives but I would recommend reprofiling the edge to an 18-20 degree standard v grind to make it nice and slicy.

[@TacticalReviews]

I know it looks like a lot of pressure as you see the strop squirming on the anti-slip material, but there are a few of factors involved. Firstly, the advantage of having a sharpness tester allows me to see what angle and pressure actually improves the edge. I can measure the effect of the stropping and see when there is an effect, or no improvement (or if I made it worse). Secondly, this is a very specific edge rolling test, and does require quite a bit of 'recovery stropping' to bring the edge back to alignment. The angle and pressure are designed to not just turn the very tip of the rolled edge back, but to try and bring the entire roll back from the base of the roll. Thirdly the strop is made from an old belt, and is a very hard leather. To get the effect I am aiming for, where the leather is applying corrective pressure at the base of the roll I need to use a reasonable pressure. (In combination with the right angle to suit that pressure) Forth on the list is the anti-slip material is a bit soft and definitely makes it look like it is getting really heavily squashed. Fifth, as you mention, the ER edge is both convexed slightly and also quite a wide edge angle, both of which mean that with this hard strop and how I want to correct the edge damage from the testing I do need to apply reasonable pressure.

[@Flockingtheherd]

@@TacticalReviews ah okay, apologies I didn’t realize you were testing different strop methods lol. I have tons of extrema ratios, no matter how I beat ‘em up, a couple quick passes on either side with light pressure make the knife razor sharp for me. Their heat treatment on n690 is amazing