Testing cts b70p

[Steeltoez83]

Im going to walk thru one of my testing styles in this thread over a few posts.. And Try to explain some backstory in the process.

The first thing i do is measure the cutting edge. I use different sized media depending on the length of that edge. Its my attempt to create a structure to categorize test samples. I use sanding rolls for my cut testing.

I have done rope cut testing in the past, what i like about the rolls is i can always recount the tickets for statiscal accuracy. I stack up piles of ten tickets and continue testing til my standards of dull are met. Now the cutting style in my opinion represents mostly a draw cut. Real world use often uses a combination of both draw and push cut without hesitation. Instead of up and down, left to right, its more of a sweeping motion. The second portion of testing will incorporate the up and down vertical push cutting into the equation to simulate the sweeping arc cutting style of most users. Once we have established how many draw cuts til our testing failure parameters are met, we can move to the second half of testing. Most use paper or magnification, i use index cards as a guide. When the apex thickens from going sharp to blunt, i needed a visual standard of measurement. My bess tester scale failed to accurately measure 180 grams consecutively so i needed a better standard. Perhaps im not the only one who tested the accuracy of the scale at different weights to validate its accuracy. I have 2 more posts to produce to fully explain the rest of the details. In terms of where my b70p mule did, i got 120 cuts before reaching my test failure.

[Steeltoez83]

During cutting im trying to produce an even workload throughout the entire edge. The area at the heel always takes the bulk of the workload initially. As the the edge begins to dull or thicken up over testing duration, the workload shifts more towards the tip area. That area has seen some workload already so its not fresh as a daisy but sharper than the heel area. That concept should make sense. Now i came up with what i refer to as the index card method. The apex has to be rather dull to not make an incision in an idex card. The incision point will move down the edge as cut testing continues. Bar screens are set at 60 degrees to allow gravity to drop debris and not be affected by downward forces. I copied that methodology and slide the apex down the index card at a 60 degree angle roughly. If i were comparing front end sharpness virtues with 2 steels id use 2 of the same models and analyze where the incision points occur. As the test drags on, i use the red line as my personal benchmark to stop testing. Ive done resting with razorblades and other thin ground knives to ensure i test only what the apex is doing. Plus one can notice nuance trends on how certain steels degrade thru use. Im simulating days of work in minutes. And i could tell heat treat differences between my bd1 manix i got awhile ago to more recent bd1 purchases from spyderco. These are my standards, ive done it for years so i can understand how it can be challenging to replicate. I think CATRA is effective at producing figures that are beneficial, but the little nuances are what i was seeking when i formulated my own system.

The last picture is to showcase what i see at the start of testing, and what the end result is when the test ends. I used my edc which happens to be a k390 leafjumper for the sharp edge, and the b70p mule for the dull portion.

[Steeltoez83]

The next part of testing can be varied depending on what im trying to identify. During my evaluation of H1 steel, i performed my normal affair cut testing and produced a number. And i searched for a cost effective repeatable media source to incorporate more vertical strikes to better balance out the draw cutting. I ended up deciding on ice. I freeze 50.7 ounces of tap water in a breadloaf pan for 24 hours. And when i tested H1 with chops into the ice block, i got the same number of strikes as the standard pure cutting test. What that told me was that H1 was going to dull at that same amount of cuts or chops. And bcuz i sharpen lower than the 15 dps, the apex is in a vulnerable state. And the ice chopping combined with pure cutting can identify how well a specific steel actually holds up when vulnerable. One can surely adjust the % of how many strikes on ice to suit the testing. Right now im operating at a 20% ice chop thats performed after 40% of the draw cutting test is repeated. The final 40% or the final steps to failure happens next. In terms of this mule i got a final figure of 105 out of 120. That tells me 87% efficiency for b70p at 13dps. Bd1N on the otberhand flatlined much quicker with a 60% efficiency. The cpm 154 had a 84% efficiency. Im using 20% but harder users/steel could gravitate towards higher percentages. I use a 1k super vit diamond stone when i set the testing edge too.

[JSumm]

This is fascinating! Do you have any charts or spreadsheets of your findings? I'm curious and I bet a bunch more folks are too.

[Steeltoez83]

Nothing for right now. I just journaled my testing experiments on IG on a daily basis. I posted some of my results here and there on this forum bcuz I felt my 2 cents added value to the convo.

[Steeltoez83]

I have a bunch of test results from testing 1k edge finishes. Here's about a 1/3 of them, I tried fitting more on to the chart making app I downloaded but it got a bit cluttered the more values I plugged in. So it makes sense to run the ice block 20% style of testing to get the edge efficiency percentages of knives I've cut tested with already. Sal seemed to take an interest in my testing style, so I hoped I explained the mindset and execution for him and anyone else who reads these posts.

[David R]

Very interesting. I've done a lot of rope cutting and have not shared the results. I find too much variability across different spools of rope. I tried several brands. Natural fiber ropes can vary by as much as 50% diameter. If I did enough testing this would all even out in theory, but I can't do the amount of testing needed to account for that. Using a consistent manufactured material makes sense.

I would watch the temperature of your ice during testing. Colder ice is harder.

[Steeltoez83]

Very interesting. I've done a lot of rope cutting and have not shared the results. I find too much variability across different spools of rope. I tried several brands. Natural fiber ropes can vary by as much as 50% diameter. If I did enough testing this would all even out in theory, but I can't do the amount of testing needed to account for that. Using a consistent manufactured material makes sense.

I would watch the temperature of your ice during testing. Colder ice is harder.

I started out doing rope cutting on 1/2 inch twisted sisal rope. I quit after I finished up the 4 or 5 spools I purchased at the start. I didn't think I could get the same brand and size consistently so that factored into the equation. Plus the last 4 knives I tested had bad hot spots, so I searched for better alternatives. As far as the ice goes, I set up testing so the ice gets used within 3 minutes of leaving the freezer. Ideally I'd want to switch back and forth between ice and the sanding roll to get a precise result. The compromise I have selected allows me to finish testing in 2 days no matter what steel I'm using. The only other time it extends past 2 days is when I'm testing longevity of the edge and incorporate the use of a strop after a set amount of what a daily workload would be. I prefer testing 3 or 4 knives at a time when I do that, and sticking to a combo of 50 slices and 10 ice chops as a simulated workday. And 10 passes per side on a diamond loaded strop afterwards to see how many days it passes my standards.

[sal]

Thanx Steeltoez,

Great stuff. Thanx much for the effort and for sharing.

sal

[Steeltoez83]

Your welcome Sal. The b70p mule was able to resist impact blows quite well. However it's ability to hold low edge angles was not good. Outside of testing, I could never find an edge finish to match this steel. Atleast nothing to extract my own perception of abstract value. I think spy27 does everything I wanted to see from this particular steel.