How sharp can you go on the standard setup?

[antrichards]

Hi!

I'm a new T8 owner and have been getting up to speed over the last two weeks. I'm now off the training wheels (I'm a knife maker and freehand grind so it's all fallen into place) and have decided that for the moment I'll stick with the standard setup (SG-250) and see how well I can do with it alone before I start going down the rabbit hole of all the other stones and after market accessories. I really don't want to be changing wheels and moving to other machines right now. The all in one solution initially sold me and I'm pressed for space in my inner city workshop.

I also purchased a BESS tester in order to have some sort of benchmark to work to.

I'm curious to know an approximate range of what people would expect to score with this setup. I understand there are variables, steel and geometry being the first two of many. However I'm totally in the dark as to what sort of scores I should expect to achieve. So far I'm averaging around the 160 mark on good quality production folding knives (Benchmade, Spyderco, ZT, etc) with working edge angles. The best I've hit so far is 139 on a small utility knife I made in Takefu SG2. I know that this steel is known for holding a fine edge so I went in on a lower angle than the folders. I'm still struggling with setting edge angles as the Angle Master provided with the T8 is soooooo hard to use to set the cutting bevel. Right now I'm either replicating angles or only adjusting them slightly.

I'm learning very quickly that the production folders generally have pretty wonky geometry and their cutting edges are not terribly neat!

Any advice is warmly welcomed.

[tgbto]

Hi!

As a foreword, remember that BESS scores are relative, they depend on how you tension the wire.

I usually get 100-110 BESS after grinding at 15dps  with the ungraded SG-250 then honing on PA-77 , with the FVB set at 2 dps more than the grinding angle.

For folding knives, you probably are around 20dps with the factory bevels, and I find the same process to yield 140-150 BESS on 20 dps. All this on standard steels around 58-60 HRC.

Cheers,

Nick.

[cbwx34]

...
I'm still struggling with setting edge angles as the Angle Master provided with the T8 is soooooo hard to use to set the cutting bevel. Right now I'm either replicating angles or only adjusting them slightly.

I'm learning very quickly that the production folders generally have pretty wonky geometry and their cutting edges are not terribly neat!

Any advice is warmly welcomed.

I  can't answer the BESS questions, but for setting the angle, I suggest using one of the calculators... an example is linked in my signature.  Way more accurate for setting angles on a knife, especially vs. the Anglemaster.

(And you're right about production folder geometry).

[John_B]

On YouTube Sharpco has a good video on how to get repeatable tension on the BESS test line. He uses a weight to set the tension.

From my reading I have seen scores of 80 using only the standard setup.

[Hannsi1957]

Hi!

As a foreword, remember that BESS scores are relative, they depend on how you tension the wire.

I usually get 100-110 BESS after grinding at 15dps  with the ungraded SG-250 then honing on PA-77 , with the FVB set at 2 dps more than the grinding angle.

For folding knives, you probably are around 20dps with the factory bevels, and I find the same process to yield 140-150 BESS on 20 dps. All this on standard steels around 58-60 HRC.

Cheers,

Nick.

Sry to correct u Nick, results from Bess Tester has nothing to do with tension of the wire.
it belongs on how fast u pull down ur knife on the wire.
if u can watch the numbers going slowly upwards u will have almost same result  no matter witch tension is on the wire

cheers
Hanns

[tgbto]

Hey Hannsi,

I understand the speed matters for the scale sampling rate, but that is not what I am referring to.

I will have to respectfully disagree though: I can break the wire just by tightening the screw. So obviously if it is tightened just before the breaking point, it will require less force to break than if it is much less tightened. There are some videos by knife sharpening forum members that show it, it was referred to here, and it is also understandable from a physics point of view: basically, to tighten a wire with a nonzero linear mass to the point that it is perfectly horizontal, you need an infinite tension, which no wire is able to withstand. If we neglect the mass of the wire wrt the force applied by the knife,  the tension of the wire varies with the inverse of the sine of the angle between the wire and the horizontal. This angle varies much with the tension of the wire, and the fissuration of the wire due to the crack propagating is also a function of tensile stress. In my experience, I can have the same knife measure B/B+40/B+40/B +/- 10 just by changing the pretension. If I tighten a lot, managing not to break the wire, I can decrease the results by another 30g.

Therefore I stick to tensioning it roughly the same way each time, and it gives me interesting, yet relative, results.

[antrichards]

Thanks for the info people. I'll check out BESS line tensions. I'm definitely doing it the same way each time and try a little push feel to see that it's relatively similar each time I set it up but I totally get that this is a pretty lo fi way to go about it. The though crossed my mind pretty quick that the tension may have an effect on scores, but I also thought that the BESS system would/should have accounted for that.

Otherwise, the only method mod I'm going with for the moment is to ditch the Tormek stone grader in favor of diamond plates mounted in the flat jig as per Kraichuk's advice. I know from grinding blades that the grinding surface is extremely important and the stone just seems a little too haphazard considering the rest of the system is more precise.

If I can get into the 100-150 range I'll be pretty happy.

Looking forwards to small production runs of my knives, I'll be looking at getting diamond of CBN wheels to get a low res but accurate "factory" edge that is quick and repeatable.

[Pietje]

Hello!
Congratulation for the new Tormek. Remember, now is the garantee up to eight years after registration.
The weight for the Bess and the CBN´s yuo can buy at https://schleifjunkies.de.
There are three different Bess, which one do You have?

[cbwx34]

Sry to correct u Nick, results from Bess Tester has nothing to do with tension of the wire.
it belongs on how fast u pull down ur knife on the wire.
if u can watch the numbers going slowly upwards u will have almost same result  no matter witch tension is on the wire

cheers
Hanns

Even the company who makes the BESS tester doesn't agree with this.... 

[micha]

Speed plays an important role, too, that's right.

But like cbw I also disagree with the 'tension being irrelevant"-theory.

"we recommend max. 100 grams of tension which is next to nothing. Over tensioning will lead you down the wrong path and intentional over tensioning can produce artificially low numbers."(Mike Brubacher himself )

I found that there is little difference between 100 grams of tension and no tension at all, but it starts making a difference when starting to raise tension from 100g upward.

[antrichards]

Pietje, I have the PT50A. Looks like I need to find a consistent way to tension the wire!

[Setarip]

I am new to tormek sharpening, but with my T8 I sharpened a stainless opinel to 15dps, followed by stropping on the tormek leather with the tormek paste. Currently this edge is tree topping some forearm hair and easily cutting free hanging hair. So I'm guessing sub-75 BESS. And I'm a newb. This is the SG-250 standard wheel as well.

[Naf]

As far as original post, seems like we're in same ballpark. My newbie opinion 100-200 not bad at all for us for relatively new and varying edge angles.

As far as wire tension, seems like that probably why they added the washer, improve tension consistency.  So... seems like some may be able break it purely by tightening while others may not be able to.   Apples and oranges?

Not discounting BESS at all!  For me personally, my different purpose is try use same way every time and gage which techniques/ products allow me achieving better results, rather than simply chasing numbers or bloating my ego.

[Ken S]

I am a long time user and believer in BESS testing. However, for everyday knife sharpening, I believe the most practical testing is a combination of copy paper and how the knife performs at the cutting board.

Ken

[tgbto]

I believe that BESS testing can help with fine tuning a process.

For instance - and spot on with the topic - I find that on low-quality knives, the lowest BESS score is achived after honing @+2dps with the standard PA-70 compound. All subsequent honing with 1micron diamond paste or Chromox, either at +2dps, +1 dps, +0.5dps result in either an identical BESS score or a higher BESS score, even if all are able to shave 80g copy paper. I am not proficient - or hairy - enough to be able to tell with confidence by any other means.

Cheers!