Protocol for BESS measurements?

[WiSpi]

For any measurement method, it is important to apply an established measurement protocol. 

For example, for outdoor temperature measurements, it was once agreed that this is done at 1.5 meters above the ground, in a cabin painted white, where the wind can blow through and the sun cannot penetrate, etc.

Is there also such a protocol for BESS measurements? 

I ask about this because I saw a video on FB that a BESS device is a waste of money. If you press the wire quickly you get a lower reading, than if you press the wire very slowly.

Would like your response.

[grepper]

You’re right.  Like any tool it should be used properly for the most accurate results.

That said, you don’t need to over think it.  Just slowly lower the blade until the media severs and BESS testers will produce very accurate and repeatable results.

To say that BESS testers are a waste of money because when used improperly they can produce less accurate measurements is like saying a table saw is a waste of money because wood can burn or cut unevenly when the wood is jammed with too much speed and pressure into the blade.  But who would do that?  Or a stove is a waste of money because food will burn if the flame is turned up too high, etc.

Here is the recommended technique for performing a test:
https://www.youtube.com/watch?v=OwD4xWZ0nXY

[WiSpi]

Thank you for your response.

It is also important to stay true to your own protocol. Mine looks as follows:
1) tension the cutting wire with a weight of 100gr
2) carefully position the blade
3) very slowly (!) increase the pressure
4) repeat the measurement 2 times (3-4 cm before the end and beginning of the blade).
5) the average is the result of the overall sharpness

Do you have any tips?

[grepper]

Good job! I would say that is perfect protocol that will produce very accurate results. In fact, you are more careful and precise about it than I am!

[WI_Hedgehog]

So there's not an official 100g tension the wire should be under?

Apparently some people "cheat the system" by over-tensioning the wire to create artificially low results, so tension contributes to the BESS score to some tangible degree.

[Macjaynard]

So there's not an official 100g tension the wire should be under?

Apparently some people "cheat the system" by over-tensioning the wire to create artificially low results, so tension contributes to the BESS score to some tangible degree.

I would love to see an official response verifying the 100g tension, if at all possible.  I saw this somewhere but can't find the reference anymore.
Thanks!

[grepper]

Thanks for the posts guys!

Sorry, but at this point since Mike’s passing, I’m probably about as “official” as you are going to get. I was Mike’s friend for years and know a lot about this stuff. For instance, the test fixture, ATF10G, is my modification of the original test fixture. Mike added the “G” for grepper.

During the development and extensive testing of test media, it was determined that 100g tension was “ideal”. But.. and this is a BIG BUT…
To be worried about the exact tension of test media is WAY overthinking the issue and totally unnecessary. Which is probably why it was removed from the documentation. It used to be there but now I can’t find it either.

Test media is not all that sensitive to a little bit of tension. It’s really amazing stuff and was a year in development and testing.
The proper amount of tension is basically no tension. The only thing you need to do is to remove any slack. When threading the media, don’t pull on it. Just gently pull it across the fixture and remove any slack.

I know that does not sound very accurate but it’s correct. It becomes super easy very quickly. Here is Mike showing how to do it:

https://www.youtube.com/watch?v=zUasWd9mUUQ

[WI_Hedgehog]

Thank you for stepping up in Mike's absence, and condolences; Mike seemed to be a great guy.

After watching the video for the third time over a period of days I understand the concept, just that for me the difference between "no slack" and 100g is 330 BESS vs 280 BESS. It could be my fat mitts (they're sizely), and I'm guessing at the tension, and I'm new at this, but there "seems to be" a need for something more consistent in my case. It doesn't seem to be the knife either, though maybe I should get some calibrated weights and test with a razor blade to cut down on potential sources of error before I run out of "test twine."

[grepper]

For testing, a DE razor blade is best. They are amazingly consistent around 50g. That will help eliminate the blade as one variable.
If you wish you can easily do the 100g thing.

A US nickel coin weighs 5g, so 20 nickels is 100g. I can pretty much guarantee that over time you will give up being that precise. You will get used to it! I suppose you could practice lifting 20 nickels to get the feel of 100g. It’s not much!

Additionally, the test media is only 0.23mm diameter, or 0.009”. So consistently hitting that exact same spot on a knife blade by hand would be extremely lucky. Hand sharpened knife blades are generally not super consistent in sharpness along the edge. Even a tiny amount of burr in one small spot will vary the sharpness reading.

I like to take 3 or so measurements along a blade and then take an average. I’m also looking for any big variation that generally is indicative of remaining burr.

Test media is not completely immune to tension. Test media clips for example put the test media under tension (sorry I can’t remember how much), and that considerable tension makes test media clips read 20% too sharp. Mike said that bending the little legs on the clips back/forth a couple of times help relieve some of the tension and makes them read closer to the hand threaded test fixture.

Hope this helps! Please let me know if you have further questions.