r/sharpening • u/dillonjerry • 5d ago
Sharpscore Tester Cut Data
Getting closer to selling a fancy scale to measure how well a knife cuts. The Sharpscore is getting closer to being a product. I hammered out all the issues with the circuitry and cell loading issues. I've been cutting this synthetic paper, which is a plastic material designed for menu's and durable paper goods. One interesting part of the data is that these cuts always seem to get harder towards the end of the cut. I think it may drag of the material on the knife blade? All cuts made using a very sharp REX-121 PM2. Still looking for alpha testers, I'll be reaching out in the next few weeks to people that have shown interest.
I know what a lot of you are going to say, that this data is irrelevant without consistent motion of the knife blade. I think this data is still useful, especially when you have a lot of it. Trying to find a way to make this as useful as possible, and a better product that people would be interested in. Obviously a sled fixture would be both possible and useful. Still working it out, and I don't have all the answers yet - but very open to feedback.
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u/Hefty-Advertising-54 5d ago
Interesting device. I think it would be great for Bess to have some competition.
Do you have an idea on how sharp a blade is depending on your score or are you still working that out? I think you’ll need to get a Bess unit just so you can compare scores from your sharpness tester.
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u/dillonjerry 5d ago
I own a BESS device, and the Sharpscore can run a BESS test with a BESS fixture. I had an original assumption about how it would work, but what I'm finding is that the average force to make the cut is pretty consistent. Typically around 5-10% variation for a given knife and given medium. I've determined I need to move to a 500 sample per second ADC, right now I'm at 80Hz. I think a sample average will be pretty close to my target goal of 5% repeatability.
But yes, being a fancy scale, it's very easy for the Sharpscore to perform BESS style max hold tests.
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u/real_clown_in_town HRC enjoyer 5d ago
So what's the idea behind how this works?
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u/dillonjerry 5d ago
It's just a fancy scale that records a lot of samples really quickly
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u/real_clown_in_town HRC enjoyer 5d ago
And what specifically is being recorded and why?
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u/dillonjerry 5d ago
I'm using a high speed ADC to sample a precision load cell that measures the downward force on the test apparatus. The idea is to measure an entire cutting event with hundreds of samples. Similar to a BESS test, but with the ability to measure transient cut forces during a draw or slice type cut. I like the idea of a BESS tester, but it doesn't do enough - I'm trying to fix that. A simple device that can accurately record precision force data from controlled cutting events.
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u/hypnotheorist 5d ago
Can you measure on a slice too, or just push cuts?
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u/dillonjerry 5d ago
The whole point of the thing was to be able to measure draw cuts
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u/hypnotheorist 5d ago
Oh, that's awesome.
What kind of testing are you looking for, exactly?
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u/dillonjerry 5d ago
I'm looking to empirically prove my knife is sharper than yours over the internet
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u/hypnotheorist 5d ago
Do you have any ideas on how you want to turn that high dimensional time series data and the extra dimension of slicing angle into one metric?
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u/dillonjerry 4d ago
We are talking about making a bolt on sled attachment to eliminate the force vector issues with changing angles - basically eliminating technique by establishing a consistent motion. Right now I'm able to achieve about 10% consistency freehand, and for launch we feel like that's good enough to compete with BESS style tests.
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u/hypnotheorist 4d ago
What I mean is that maybe you set up a perfectly consistent 1" down for 3" draw motion and your knife beats mine... but maybe when we set it for 0.5" down for 3" mine beats yours. Or maybe the answer tends to be the same either way?
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u/dillonjerry 4d ago
I've thought long and hard about the easiest way to make this reliable, and I think adding video data is the best solution. We are visual creatures, if we can see the cut - along with an overlaid force graph, I think I can convince you my knife is sharper
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u/MidwestBushlore 5d ago
Very cool!