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Tricking the BESS Tester (without meaning to) - blgentry - 03-25-2020

I just did some more work on my (now world) famous Tramontina kitchen knife.  The one that scored about 190-ish after very careful deburring, following a 380 grit belt.  Well I decided to polish it a bit so I used a 600 grit belt, then leather, scotchbrite, leather again.  Terrible scores!  200, 350...  So more polish.  I went straight to a smooth leather belt with green compound.  Very little compound left on the belt, but it's there.  Eliminated the remaining LOW.  ...and it scored 125, 125, 175.  The 175 was in the curve.  So back to the loaded leather.  I did 5 or 6 passes and got a little too casual with my motions.  Sliced open the top of my index finger.  Ooops.  Nice *cleeeeeean* cut though.  It didn't even bleed for 20 or 30 seconds.

After cleaning that up, I tested the curve again.   One handed, because I was holding pressure against the finger of one hand.  Balanced the blade on the fulcrum on the tester, and leaned it over to the media.  Lean, lean, lean, lean... and the media broke.  At 80 grams.  No freaking way.  I must have sliced it somehow.

So I went and got a bandaid and got my finger taken care of.  ...and tested again.  In the curve with the fulcrum, but this time with the other hand on the tip of the blade helping to guide it down.  ...and it read 135.  Now that's more believable.

I can only guess that with one hand the blade slips some and creates a slicing motion, which obviously "tricks" the tester because the force is not straight into the media, it's at an angle.  I think if you were really clever you could slide the blade sideways and get nearly zero readings by doing an extreme version of this.  Does that sound about right?

Anyway, seems like I need to be more careful when sharpening knives.  Smile

Brian.


RE: Tricking the BESS Tester (without meaning to) - chino - 03-25-2020

Nice! I love it when knives bite their owners... LOL (I have 16 stitches on one hand... The knife was plenty hungry)


RE: Tricking the BESS Tester (without meaning to) - Mike Brubacher - 03-25-2020

" I love it when knives bite their owners." That one made me laugh Chino - good job. Perhaps Brian should think about having that knife put down.


RE: Tricking the BESS Tester (without meaning to) - chino - 03-25-2020

(03-25-2020, 01:59 PM)Mike Brubacher Wrote: " I love it when knives bite their owners." That one made me laugh Chino - good job. Perhaps Brian should think about having that knife put down.

Nah, as long as rabies aren’t in the equation it’s just fine... Big Grin


RE: Tricking the BESS Tester (without meaning to) - grepper - 03-25-2020

"Sliced open the top of my index finger.  Ooops."

I just hate it when that happens.  It never seems to work to try and control the epidermal leakage and keep working.  Always have to give in and go deal with it.  No doubt you will find that you use that one spot on your finger about 1,000 times a day.

"LOL (I have 16 stitches on one hand... The knife was plenty hungry)"

Yikes!  I just really, really, really hate it when that happens!


RE: Tricking the BESS Tester (without meaning to) - chino - 03-26-2020

Yeah the ER nurse (almost) gasped when I took the paper towels off.

Ok, sorry about derailing this thread.

I watched the latest video on paper cutting and enjoyed it.


RE: Tricking the BESS Tester (without meaning to) - subwoofer - 10-19-2020

Not to be uncaring, but on the original topic...

In my experience, it is the media tension that is most critical here. Correct me if I'm wrong - If you have it set right, the filament is slightly slack so should be able to swing and absorb any minor movement.

If however you over tension, the media is too tight and is then much easier to cut. If you really go for it, this could make readings much much lower than they should be.

Are you using the bearing version of the media clamp?


RE: Tricking the BESS Tester (without meaning to) - grepper - 10-19-2020

"Correct me if I'm wrong -"

Well, okay. Smile   You are 50% correct. 

Negative on the slack media.  EOU specifies the ideal test media tension with the ATF series is 100g.  That's the same as 17.63 US quarter dollar coins or 20 US nickel coins.  Not much tension, but not slack.

You are correct on over tensioned media.  Over tensioned media can indicate sharper than normal readings.  Test clips for instance read 20% too sharp.  This can be normalized by wiggling the legs holding the media to loosen the media slightly or normalizing the reading by -20%.

That said, it's not all that sensitive or critical and you don't need to over-think it.  When threading the media, just pull it across and gently remove the slack.  

Slicing the media instead of push cutting will cause over sharp readings.  Proper technique is to slowly push cut the media with the blade perpendicular to the media.


RE: Tricking the BESS Tester (without meaning to) - subwoofer - 10-20-2020

And this is where it becomes impossible, setting a tension of 100g. There is no way this can be done with an ATF. Even if you could set that and then not change it when securing the clamp, as soon as an edge is brought down onto it everything changes.

My guestimate was perhaps badly expressed. I take up the slack in the filament without tugging hard, and then tighten the clamp nut. One done I gently poke and pluck the filament to get a sense that it is not actually slack, but also not tight. A bit vague but certainly works better than de-tensioning the clips.

My feeling was that as the filament can move a little that small slicing movements (very small) from hand holding should be absorbed, but large slicing motions would totally blow the measurement.

Still considering false readings, I find that when placing the ATF into its cut out, it is possible for it to get caught up on the metal plate. I actually test for this by pressing down hard on a fulcrum sitting on the plate and check for the reading staying at 0. If it registers anything, the ATF is touching the metal plate. If you didn't check this I can imagine a reading being very badly off if the ATF catches the plate.


RE: Tricking the BESS Tester (without meaning to) - grepper - 10-20-2020

"I take up the slack in the filament without tugging hard, and then tighten the clamp nut."

You got it!  That is proper procedure.

"I find that when placing the ATF into its cut out, it is possible for it to get caught up on the metal plate."

Yeah.  I've seen that too.  The rubber boot on the bottom of the ATF can rub on the edge of the top plate if the ATF is not centered in the cutout.  It would be nice if the cutout was of larger diameter.  It wouldn't be too hard to grind the cutout to be a bit larger if you cared enough to bother with it.