Protocol for BESS measurements?

[grepper]

Cool! Thanks for sharing. Could you post an image of your tensioning device? Your question is a common one and I'm sure other folks would be interested too.

[WI_Hedgehog]

My BESS readings were initially not repeatable, so I wondered where the inaccuracy was being introduced.

I tested the BESS tester with a series of calibrated weights and mine is 100% accurate across the whole range (which is quite impressive). Reasonable amounts of magnetism do not affect measurements.

I was applying pressure slowly and steadily, straight down, perpendicular to the test media, in the same spot on the blade, and eventually moved to a highly refined blade--toothyness can make a big difference, likely the biggest factor in lack of repeatability.

With testing I found media tension in this configuration is probably the second largest influence on repeatability, at least for me; some days I could see a +/- 20g difference from the average value.

The media tensioner design is intended to be as simple and basic as practical, plus be rust resistant.

A chrome plated clip on the end of 400-Series (magnetic) Stainless Steel cable pinches the BESS calibrated test media to tension it (some filing so the clip closed tight enough was required).
https://www.amazon.com/dp/B0CCJ86F62

The far end of the magnetic stainless cable touches a neodymium cup magnet (facing up) which holds everything together. I stick the tool in the upper-left of the BESS Tester when not in use, opposite the trash bin on the right; it has enough strength on the weak side to hold the tensioner to the BESS tester without holding it "too strongly."
https://www.amazon.com/dp/B01MRT31RM

A chrome plated calibrated 50g weight is placed on the cup magnet so the sum of the weights is 100g (technically the assembly is 5g light, another 5g calibrated weight is needed).
https://www.amazon.com/dp/B08SQ2WTNY

A small plastic bag encloses the magnet assembly to keep small magnetic debris from permanently attaching to the magnet. Cling wrap could also be used though make sure there's enough of an opening for moisture to escape.

Assembly is truly as simple as "pile it all on the magnet and put it in the bag."

A "trash bin" is secured with a second cup magnet (who owns just one???) on the right side (just put the magnet in the container--that's it).
Wide-mouth Leak Proof Plastic Container
https://www.amazon.com/dp/B0DPG6HQNZ


The tensioning procedure is simple, and I'll describe how I do it in detail (someone will wonder how I claim it's so fast and easy) because it's far faster than pinching the media by hand--and it uses less media:
1.) Pick up the test fixture and spin the take-up nut (opposite the spool side of the test fixture) 1 turn, grap the cut test media and throw it away in the trash bin.
2.) Spin the take-up nut open another turn and if gravity doesn't do the job pull the washer down so the alligator clip clears the washer.
3.) Spin the supply nut open 1 turn.
1-3 can be done smoothly in about 5 seconds without rushing.

4.) Stabalize the alligator clip from turning between your fingers with a finger from the hand holding the test fixture, using the fingers on the other hand to pinch the clip open.
5.) Put the end of the test media in the clip opening and release the clip.
6.) Lift the test fixture until the media falls into the slot and the end of the alligator clip clears the washer by 2mm.
7.) Tighten the supply nut on the spool side (while still lifting the test fixture).
8.) As the weight lifts off the non-magnetic counter, tighten the take-up nut.
4-8 take about 10 seconds without rushing

9.) Lower the test fixter and release the alligator clip.
10.) Center the test fixture on the scale.

Fifteen seconds, that's it; twenty if you fumble the alligator clip, and it still uses less media than pinching the media with fat fingers. Five if everything goes perfectly smoothly--not that the extra seconds are critical, but the thing is that recording the heel, center, and tip sharpness accurately takes under one minute.