Edge Tester - 3D

777 Edge

Dealer / Materials Provider
Joined
Sep 16, 2019
Messages
1,135
Here is a design I just finished a couple days ago and have been testing it extensively over the last few days. It is based on the popular, but expensive, BESS Edge-On-Up sharpness tester.

I use 0.325mm monofilament fishing line, and a Feather DE razor blade as my calibration value. I also make sure that the line is NOT tight, it seems to need a little bit of slack in it for the cutting value to be consistent. If too tight, it cuts way too easily. If I leave some slack in the line, the values are very consistent.

As with all my other designs, this one is available for free for anyone with access to a 3D printer.

https://www.thingiverse.com/thing:4781467

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Update -

After experimenting a lot with the 0.325mm monofilament fishing line, I keep getting very consistent results when the line is slightly slack. This seems to be an important factor and I assume the same applies to the BESS certified filament. It should not be tightened.

Tightening the line makes for completely inaccurate results because of the tension in the line. When I tighten up the 0.325mm fishing line, the results read anywhere between low as 1g and as high as 30g(random results), and when I leave a little bit of slack in the 0.325mm line, I get very consistent readings of around 65-70 grams. This is a very good calibration point to compare with other edges.

I will purchase some 0.2mm monofilament fishing line over the next few days and run some tests as a comparison and see what the calibration results are with 0.2mm. I think 0.2mm line with a little bit of slack in it will likely yield very similar results as the BESS certified filament. Will post the results when I'm done testing.
 
You can't be serious saying that the Edge On Up BESS tester is "expensive". A quality lab scale with memory costs not much less. For consistency you need a platform and fulcrum.
For the sharpness score to be meaningful to others, the instrument must be calibrated to the BESS sharpness scale.
The Feather DE razor should score 30 g. as you can see here https://www.refinedshave.com/razor-blade-sharpness-testing/


For calibration the instrument needs a firmware chip. See the 2 calibration buttons on the panel - the ones with the screw head symbol?

The PT50 BESS tester is a system, not just test line and a scale.
The PT50B updates the display every 100ms, the PT50A every 40ms. The average kitchen scale does so every 1.5 seconds. That's 15 times slower than the PT50B, and because of that the reading you see is always higher than what we see on the BESS testers.
Speed is critical to accurate measurements in that we want to capture, as closely as possible, the actual moment of severing the test line.

A fishing line has inconsistent diameter along its length, and because of that the test score varies even when measured on the BESS tester; contrary to that the BESS certified test media has a highly consistent diameter.
 
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Another great tool for tool users! Nice summation wootzblades. Some day I'll buy one.
777 Edge, keep playing, love your work - Over clocking for higher sample rate from 1.5/sec to 40ms would surely break things... maybe. Medical / aerospace supply houses for certified line?
Remember, upfacing and down facing cameras on Perseverance package were tweaked and hardened off the shelf from ~2019. Geez, Perseverance even has a small rotor wing to fly, in not much Martian atmosphere, Iv'e gotta find out more (I remember a proposal that did not win funding, to launch a fixed wing camera package there, back in the quick and less expensive project days, the wing span was huge and weight was saved by launching from a rail.)
Old brickyard quote- Question is not how fast you want to go but how fast you want to spend?
thx
 
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You can't be serious saying that the Edge On Up BESS tester is "expensive".

Last time I checked, the PT50A with 1 g resolution is $259. I would call that very expensive. My digital scale was $16 and if I measure slowly, the refresh rate on it is just fine.

I just did some more tests with 0.165mm line and 0.235mm line and so far I am getting exceptional results with the 0.165mm line. Consistent 25-30g values with a new Feather DE blade, and around 50-55g values with a Gillette DE blade. The 0.235mm line values are still a bit too high.

Looks like 0.2mm or less is the best to use.

I'll run some more tests and post the results.
 
Good on ya, 777. Don't fret the naysayers. Your implementation is clever and could be useful. I'm always intrigued by you 3-D printer guys. When I see something like that, my brain goes to aluminum and a lathe. I wouldn't know how to get started using your tools. Thanks.
 
777 Edge, I look forward to your progress reports. The skilled practice and tester that will come out of your work are interesting. Remember though, the Wright brothers sold 25 1903 flyers to the feds, and everyone of them crashed, even though the brothers flew them and their predecessors successfully...
I searched BF on the string "Edge On Up BESS" and found 4 pages of hits. The 13 page thread that put the tester on my radar is "Edge Sharpness Tester"

I always had my eye on the PT50B, whose resolution seemed appropriate for our purposes. Price seems right, but I have two teens temporarily renamed locust #1 and locust #2, so no Edge On Up yet, if you get my drift. Calibration on BESS standard is sweet, and allows users to share common info within error bars. Following the Edge On Up development seemed like heavy lifting to me. I remember pricing parts and evaluating the work, for a kid's analog to digital project, and quickly concluding a cheap dumb scale would not meet our testing needs. As I learned about specific hardware and software solutions of the tester, I was soured me on less precise outcomes. Way more hack then kids making an integrating sphere to measure flashlight lumens, where you buy electronics prebuilt.
 
777 Edge, I look forward to your progress reports. The skilled practice and tester that will come out of your work are interesting. Remember though, the Wright brothers sold 25 1903 flyers to the feds, and everyone of them crashed, even though the brothers flew them and their predecessors successfully...
I searched BF on the string "Edge On Up BESS" and found 4 pages of hits. The 13 page thread that put the tester on my radar is "Edge Sharpness Tester"

I always had my eye on the PT50B, whose resolution seemed appropriate for our purposes. Price seems right, but I have two teens temporarily renamed locust #1 and locust #2, so no Edge On Up yet, if you get my drift. Calibration on BESS standard is sweet, and allows users to share common info within error bars. Following the Edge On Up development seemed like heavy lifting to me. I remember pricing parts and evaluating the work, for a kid's analog to digital project, and quickly concluding a cheap dumb scale would not meet our testing needs. As I learned about specific hardware and software solutions of the tester, I was soured me on less precise outcomes. Way more hack then kids making an integrating sphere to measure flashlight lumens, where you buy electronics prebuilt.

Luckily for me my kids are grown, I guess. So, I have a PT50A on the way home to me. That way my results will actually mean something to other people.
Threads like this remind me of when I was a kid watching my dad wasting time messing around with used tires. That's not counting the time wasted changing flats, and the time wanting to change a flat but the cheap used tire he bought was flat when we needed it. Finally, I convinced my dad how much time and money that he was actually losing messing around with those cheap-ass used tires. Life was better when our car had new tires on it. :)
 
After a few hours worth of testing on 0.165mm and 0.235mm monofilament fishing line, I am very happy with the consistent results I am getting from the 0.165mm line.

The 0.165mm line results are surprisingly close to the BESS numbers on the sharpness chart thread here (sticky thread with this link - http://knifegrinders.com.au/Manuals/Sharpness_Chart.pdf )

It is clear that there is a bit of a "learning curve" to make sure it is done the same every time. The line needs a slight bit of slack, the push force and time needs to be about the same - slow and steady wins the race. It took me about 20 minutes or so of practise to get VERY consistent numbers (all numbers within a 10% value) and I think anyone can get good results with only a little bit of practise, using the 0.165mm monofilament line. It is important to watch the scale like a hawk. Even though my $15 AWS(American Weigh Scales) Blade scale is very accurate, it does not have a peak saving function and does not have a fast refresh rate so you need to slowly add pressure and watch it carefully, or make a slow motion video recording with your phone to check your results.

Here are some of my results: (The results are mean values of 10 cut tests each time)


DAHE brand 0.165mm monofilament fishing line:
  1. Feather DE blade - 28g
  2. Feather cut special platinum coated blade - 33g
  3. Feather professional super (artist club) - 36g
  4. Vantage hair shaper blades - 44g
  5. KAI captain blade (injector) - 49g
  6. Spyderco Maxamet Native 5 (My EDC knife) - 106g (It "fillets" printer paper very easily, and shaves arm hair completely effortlessly)
  7. ZT 0640 (has not been sharpened in a while) - 221g (Cuts receipt paper easily, does not quite fillet printer paper, barely shaves arm hair)

DAHE brand 0.235mm monofilament fishing line (Same blades as above):
  1. Feather DE blade - 42g
  2. Feather cut special platinum coated blade - 47g
  3. Feather professional super (artist club) - 51g
  4. Vantage hair shaper blades - 66g
  5. KAI captain blade (injector) - 68g
  6. Spyderco Maxamet Native 5 (My EDC knife) - 163g
  7. ZT 0640 - 357g
For reference, below is a link of a clip of a slow motion video with my phone (bad quality video) of one of the tests I did with the 0.235mm line and my Native 5. The line cuts at a peak force of 166.1g, and you can actually see it with your naked eye if you pay attention while running the test. I found that a video is not necessary at all, just watch your scale while you slowly cut the line. Video just for reference.
https://photos.app.goo.gl/QFtdnZL7E8HjYSdK9

In summary, I am very happy with the 0.165mm line. I have not found 0.2mm line yet locally but I am keen on trying it, and some more expensive braided line too but it's unlikely that the results can get much better than what I have found with the 0.165mm line.
 
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Great find Mr Wizard!

If I can get my hands on some 0.21mm fluorocarbon, I will definitely run the tests with that too. I hope I can find some locally.

Interestingly, it seems that monofilament of around 0.2mm also does a good job.(The 0.165mm monofilament I tested gave me great results) Maybe fluorocarbon might not even be necessary but I definitely want to test it.
 
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Wait a minute here to the naysayers- OK, so this isn't going to be apples to apples with what's out there, but if we use this setup consistently, why wouldn't it be a legitimate way to test the edge? Not being sarcastic, it's an honest question. The "poor man's" edge tester- as long as everything is consistent, why can't we begin using this setup as an alternative?
I would guess that monofilament is VERY consistent from spool to spool, so why can't we just create whole new set of numbers using this design?

The only thing I did not see (and maybe I just didn't read carefully enough) is how much slack to give. But that seems easy enough to fix but naming the exact brand and pound test along with the exact length of line.

Am I missing something here? This seems like a very good way to get results that are accurate to at least 1 decimal place which is probably close enough.

Does it matter what kind of filament is used? Would the type of filament matter because it would be more or less flexible and skew results?
 
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Please take discussion of arranging printing, shipping etc to PM or email as this is not the appropriate venue for such.
 
Wait a minute here to the naysayers- OK, so this isn't going to be apples to apples with what's out there, but if we use this setup consistently, why wouldn't it be a legitimate way to test the edge? Not being sarcastic, it's an honest question. The "poor man's" edge tester- as long as everything is consistent, why can't we begin using this setup as an alternative?
I would guess that monofilament is VERY consistent from spool to spool, so why can't we just create whole new set of numbers using this design?

The only thing I did not see (and maybe I just didn't read carefully enough) is how much slack to give. But that seems easy enough to fix but naming the exact brand and pound test along with the exact length of line.

Am I missing something here? This seems like a very good way to get results that are accurate to at least 1 decimal place which is probably close enough.

Does it matter what kind of filament is used? Would the type of filament matter because it would be more or less flexible and skew results?

The amount of slack I've tested does not seem to matter too much, as long as there is just a bit of slack in the monofilament line.

This is how I use it with very consistent results-

I pull out about 2 inches of line and lock it again with the side locking screw. Then I place it under the second (diagonal) locking screw (I don't wrap it around the screw, I just lay it under the side). I then very slightly push down on the line in the testing gap while tightening the screw, making sure that the screw doesn't tighten the line again. When both screws are tight, I feel the line with my finger just to reconfirm that it is not tight at all.

The exact amount of slack doesn't seem to matter, just a tiny bit seems to work well. If it is pulled tight the testing is very inconsistent.

As for the monofilament line, even my cheap chinese 0.165mm line is very consistent and I don't think it's consistency would affect the test at all, especially if you do 5 tests per knife and use the mean average.
 
Threads like this remind me of when I was a kid watching my dad wasting time messing around with used tires. That's not counting the time wasted changing flats, and the time wanting to change a flat but the cheap used tire he bought was flat when we needed it. Finally, I convinced my dad how much time and money that he was actually losing messing around with those cheap-ass used tires. Life was better when our car had new tires on it. :)
Is this to say don't waste money on an edge tester and instead invest in something practical like tires for safe and reliable transportation? It certainly can't be suggesting that a scale with 1 gram resolution for cutting thread is a wise investment of time and money.

I did a search because I'm going to buy a PT50A, because I want a new toy. That's effectively what it is, and the results will only be me playing around. Nothing important will come from knowing the difference of a cut down to a single gram for my freehand edges on my personal knives. It is unimportant and irrelevant to everyday life and every cutting task of a normal knife.
 
Is this to say don't waste money on an edge tester and instead invest in something practical like tires for safe and reliable transportation? It certainly can't be suggesting that a scale with 1 gram resolution for cutting thread is a wise investment of time and money.

I did a search because I'm going to buy a PT50A, because I want a new toy. That's effectively what it is, and the results will only be me playing around. Nothing important will come from knowing the difference of a cut down to a single gram for my freehand edges on my personal knives. It is unimportant and irrelevant to everyday life and every cutting task of a normal knife.

No. The moral of the story is why waste time and money with cheap stuff when you can get the good stuff. The PT50A is cool to have but it's really for push cutting. Have fun.
 
This looks very much like the BESS Edge On Up design. In fact, it looks like a straight up copy. That's not clever. That's just replication.

You may feel like you are being frugal and clever by doing your own testing and developing something that "everyone can use for free". I see this as being much closer to theft than altruism or frugality.

Think of the money that Mike has invested in developing his product. Your actions could harm his business. Which wouldn't be any big deal if you were developing something OF YOUR OWN. But you're not. You're just copying something and trying to make it look like a "great less expensive option to that over priced thing over there". I find your actions to be unethical.

I am in no way affiliated with Edge On Up. I am a customer. I own one of their products, which I paid full price for.

Brian.
 
You're just copying something and trying to make it look like a "great less expensive option to that over priced thing over there". I find your actions to be unethical.

Brian.

Hi Brian, perhaps you should read the second sentence in my first post again. I very clearly said this is based on the BESS Edge-On-Up sharpness tester. All recognition to them, I never said this is my invention or idea.

This is an experiment. I need a holder for various fishing lines, not BESS test media. The experiment here is to compare other test media types.

The actual Edge-on-up Aluminum Test Fixture that I based this DIY project design on is only a $35 part from Bess Edge on up. Their actual "tester" is the scale for the PT50A and B that they make and sell. How that scale operates, is where they did all the work and absolutely deserve recognition for it.

What I'm trying to do here, is see how inexpensive fishing line and a cheap digital scale compares as an experiment.

FYI, anyone can buy the $35 Aluminum Edge on Up Test Fixture and use it on a home kitchen scale to do exactly what I'm doing with mine, but you can't use fishing line in it. I want to experiment with fishing line in stead of the "official" test media and apparently it's not possible to do that with the Edge-on-up aluminum holder so I had to make something slightly different.

I don't have an "official" PT50A or B tester, nor do I have a Aluminum test media holder to "copy" so I can't actually tell what the internals of the holder is like at all. I can't imagine their internals working exactly the same as the one I made, because the BESS test media comes in a container, not a wind-able reel. Internally, mine is designed like a swappable fishing reel.

Yes, I absolutely made this DIY version look aesthetically similar so when an avid sharpener looks at it, they will know what exactly it is they are looking at.

It's a spool for fishing line in a tube with 2 screws holding the line in place over a gap to cut...it's not a new cancer therapy and it's not some evil villain's master plan to take business away from anyone. It's an experiment to learn more about push cut testing, using alternative media and a basic digital scale.

Interestingly, originally I considered making my holder square for better placement and alignment on my small scale, but then my threaded bottom cap and round fishing line spool would not work nor would anybody recognize it for what it is when they see it. A picture says more than words. The Edge on up holder doesn't close with a threaded cap, nor does it have an internal axis for a fishing line wind-able reel.

For anyone to make one of these holders themselves at home they would need to buy a 3D printer first, so unlikely in most cases. I have, and use a 3D printer and 3D designing software daily so it makes sense to make stuff for myself where I can, especially when experimenting with something.

The scale I use for my experimentation is a kitchen scale, not a PT50 Bess Edge on up scale "copy" nor anything even close to it, unless you think using a kitchen scale is copying what Edge on up does?

Edge on up use "official" test media, I use plain old fishing line. Is store bought fishing line also a "copy" of their test media?

Lastly, this is an openly shared and FREE design. A 3D printable or CNC machinable design downloadable in STL file format. There is no other design I could find to print for this experiment. I 3D modeled and printed one for myself and made it available for anyone else who would like to run the same experiment. Since when is openly sharing home made DIY projects for experimenting and information such an issue?

If you were to make yourself a pot hanger handle for your kitchen wall and you make it aesthetically match the Home Depot hand towel hanger attached to the wall next to it, would this be theft of a Home Depot hanger? How about being good at woodworking and making an extra kitchen cabinet door that looks like the IKEA ones in your kitchen. Making another one for yourself is theft?

Have you ever made yourself a new knife handle to match the other side scale that has broken off? Have you ever made a metal bracket with your milling machine to mount something on your Ford pick-up truck but made it match the Ford looks? Have you ever made any wooden chairs to visually match the other store bought chairs in your house? I guess not, that would be unethical, right?

This is a spool holder based on Edge On Up. I said that in my very first post. This whole exercise is an experiment for comparison. If the Edge on up holders could take normal fishing line in a small reel, then I'd love to experiment with it but apparently it can not. This is an experiment meant for sharpening nerds like myself, so see it for what it is.
 
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You are obviously copying the entire idea including the exact look (if not exact internal design). If you don't have a problem with that, I won't try to convince you of my position.

Brian.
 
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