Tormek Community

In the Shop => Knife Sharpening => Topic started by: van on April 19, 2019, 05:00:32 pm

Title: Positive or negative smoothing
Post by: van on April 19, 2019, 05:00:32 pm
Excuse the profane question.
If one does not have a Bess or a tester available, how can he know if a burr is positive or negative?
To be able to carry out the most suitable sanding.
Thank you.
Title: Re: Positive or negative smoothing
Post by: wootz on April 19, 2019, 10:58:31 pm
Our "Knife Deburring" research discriminates burrs into "positive" that should be honed at a higher angle to get the edge sharper, and "negative" that should not.
In the context of knife sharpening, the term “negative burr” is an umbrella term, not fully matching the connotations given to it in the metallurgical science.
There is a branch in cognition science about human thinking based on polarized constructs. We've introduced this "positive-negative" construct to make selection of deburring method easy. This "positive-negative" logical construct helps us to choose the right honing method.

Van, if you cannot see your knife steel in the "Knife Deburring" book, the chapter SELECTION OF A DEBURRING METHOD, feel free to email me and I will advise the honing method to get the best sharpness and edge retention on your particular steel, as we keep records of all knife steels we sharpen.

You can detect the wire edge that forms when you hone the "positive burr" at the edge angle, even if you do not have a sharpness tester.
I'd say everyone who wants lasting sharpness should learn to detect the wire edge, because the wire edge gets crushed under the cutting load, rendering the edge dull; it is the main cause of your knives dulling early.

So, you have apexed your blade, and honed it on the Tormek leather wheel with the Tormek honing compound at the edge angle.
You cannot feel or see any burr, the edge cuts paper and shaves your forearm.

We know that, honed at the edge angle, the base of the "positive burr" will be shaped into the wire edge, while the "negative burr" knife steel will not. The base of the burr is called "burr root" in the specialist literature. The micro-hardness in the burr root is higher than in the base metal, allowing to hone it into a very sharp but unstable wire edge.
While it is not easy to detect wire edge in hard alloy high-end knives without special equipment, it is relatively simple in mainstream knives.
Even if you do not own a BESS sharpness tester, you can do a simplified test for wire edge by cross push-cutting a stretched fluorocarbon fishing line, and checking under good light or with a loupe if the very edge has got a micro-dent in the point of the cut – wire edge will dent, while the cleanly deburred apex will not.
Similarly, "positive burr" deburred at the edge angle will micro-dent, while the "negative burr" will not.
The fluorocarbon fishing line must be 7 LB 0.21 mm or near that.
Microscope image follows, but this dent can be seen with the naked-eye by scattered light.

(http://knifegrinders.com.au/photos/SWIBO_10_degrees.jpg)

On the wire edge the sharpness tester will show over 300 BESS, 500-600 BESS is not unusual, and 500 BESS is a dull knife.

I wrote the "Knife Deburring" book to explain types of the burr we get on knives and give all facts one may need to make his own informed conclusions and develop sharpening procedures that eliminate the wire edge, providing for lasting sharpness.
But if you don't feel like reading through the book, you can take my word for it, and simply follow our sharpening protocols. Our sharpening protocols by knife steel are detailed in the DEBURRING chapter of the book, but the basics are available for free in the evaluation version of the Knife Deburring book on our website, in its Sharpening Resources section.




Title: Re: Positive or negative smoothing
Post by: john.jcb on July 05, 2019, 03:35:53 pm
Following the sharpening and deburring processes from the "Knife Deburring" book has taken my results to another level.

I am now contemplating getting another leather wheel and using an even finer honing compound.

If I will only have one compound finer than the Tormek paste what would you suggest?
Title: Re: Positive or negative smoothing
Post by: john.jcb on July 05, 2019, 04:29:51 pm
I see the answer was just posted here:

https://www.tormek.com/forum/index.php?topic=3685.msg27666#new
Title: Re: Positive or negative smoothing
Post by: wootz on July 05, 2019, 04:37:34 pm
Tormek honing paste is said to initially have 3-6 micron grains, with the majority near 3 microns, that with use break down to 1-micron grains.
Gap in honing grits usually goes by one order of magnitude.
So the next honing wheel after the Tormek honing paste should have grains of abrasive within 0.1-0.3 micron.

Chromium Oxide is in this range, as is diamond paste or thick emulsion of 0.1 micron, and up to 0.25 micron.
Unlike wth the Tormek honing paste, the finishing wheel layer should be very thin and well rubbed into the wheel, and the wheel itself should be smooth.

In the past I used CHROMOX with 0.25 micron diamonds on the finishing leather wheel, but nowadays I "paint" the wheel with the chromium oxide in oil, and rub in Jende 0.1-micron diamond emulsion.
Title: Re: Positive or negative smoothing
Post by: MrSwede on July 16, 2020, 08:03:16 pm
Our "Knife Deburring" research discriminates burrs into "positive" that should be honed at a higher angle to get the edge sharper, and "negative" that should not.
In the context of knife sharpening, the term “negative burr” is an umbrella term, not fully matching the connotations given to it in the metallurgical science.
There is a branch in cognition science about human thinking based on polarized constructs. We've introduced this "positive-negative" construct to make selection of deburring method easy. This "positive-negative" logical construct helps us to choose the right honing method.

Van, if you cannot see your knife steel in the "Knife Deburring" book, the chapter SELECTION OF A DEBURRING METHOD, feel free to email me and I will advise the honing method to get the best sharpness and edge retention on your particular steel, as we keep records of all knife steels we sharpen.

You can detect the wire edge that forms when you hone the "positive burr" at the edge angle, even if you do not have a sharpness tester.
I'd say everyone who wants lasting sharpness should learn to detect the wire edge, because the wire edge gets crushed under the cutting load, rendering the edge dull; it is the main cause of your knives dulling early.

So, you have apexed your blade, and honed it on the Tormek leather wheel with the Tormek honing compound at the edge angle.
You cannot feel or see any burr, the edge cuts paper and shaves your forearm.

We know that, honed at the edge angle, the base of the "positive burr" will be shaped into the wire edge, while the "negative burr" knife steel will not. The base of the burr is called "burr root" in the specialist literature. The micro-hardness in the burr root is higher than in the base metal, allowing to hone it into a very sharp but unstable wire edge.
While it is not easy to detect wire edge in hard alloy high-end knives without special equipment, it is relatively simple in mainstream knives.
Even if you do not own a BESS sharpness tester, you can do a simplified test for wire edge by cross push-cutting a stretched fluorocarbon fishing line, and checking under good light or with a loupe if the very edge has got a micro-dent in the point of the cut – wire edge will dent, while the cleanly deburred apex will not.
Similarly, "positive burr" deburred at the edge angle will micro-dent, while the "negative burr" will not.
The fluorocarbon fishing line must be 7 LB 0.21 mm or near that.
Microscope image follows, but this dent can be seen with the naked-eye by scattered light.

(http://knifegrinders.com.au/photos/SWIBO_10_degrees.jpg)

On the wire edge the sharpness tester will show over 300 BESS, 500-600 BESS is not unusual, and 500 BESS is a dull knife.

I wrote the "Knife Deburring" book to explain types of the burr we get on knives and give all facts one may need to make his own informed conclusions and develop sharpening procedures that eliminate the wire edge, providing for lasting sharpness.
But if you don't feel like reading through the book, you can take my word for it, and simply follow our sharpening protocols. Our sharpening protocols by knife steel are detailed in the DEBURRING chapter of the book, but the basics are available for free in the evaluation version of the Knife Deburring book on our website, in its Sharpening Resources section.


A question from a stupid swede about the fishingline . Is it 7 pounds breakingpoint and 0.21 mm in diameter?
Title: Re: Positive or negative smoothing
Post by: cbwx34 on July 16, 2020, 08:55:16 pm
A question from a stupid swede about the fishingline . Is it 7 pounds breakingpoint and 0.21 mm in diameter?

This thread has some info.... Replacement for BESS certified test media (https://www.australianbladeforums.com/vb4/knife-grinders/39974-replacement-bess-certified-test-media.html)
Title: Re: Positive or negative smoothing
Post by: Hannsi1957 on July 18, 2020, 02:33:18 pm
In principle it does not matter which medium you use because the results are not comparable.It depends on several factors that have too many sources of error to compare better values. On my youtube channel I have made an example video. With the same knife you can compare values from 50 to 120 bess. This device is great but only to test yourself. Comparing with others is very inaccurate.
So it dont matter witch medium u use. Use it 4 urselve.
Title: Re: Positive or negative smoothing
Post by: MrSwede on July 18, 2020, 03:06:37 pm
I was just about to ask something like this. Im not looking for a media to messure the edge, just to fold/damage the last small burr so I can see it in my microscope. Then I can just use something thats close to wootzs specs, right?
Title: Re: Positive or negative smoothing
Post by: jvh on July 18, 2020, 07:53:51 pm
In principle it does not matter which medium you use because the results are not comparable.It depends on several factors that have too many sources of error to compare better values. On my youtube channel I have made an example video. With the same knife you can compare values from 50 to 120 bess. This device is great but only to test yourself. Comparing with others is very inaccurate.
So it dont matter witch medium u use. Use it 4 urselve.

Hello,

this is very interesting and your video (https://www.youtube.com/watch?v=dQFTAlAgCXg) too. Thank you for pointing this, it changed my view on this device, because the results can be easily manipulated, so their informative value is questionable. Measured values range is just too large.

For me it looks like an another marketing tool now, because it's not possible to hold/verify used methodology. But I agree that is still very good for the personal growth.

jvh
Title: Re: Positive or negative smoothing
Post by: smurfs on July 19, 2020, 12:01:17 am
In principle it does not matter which medium you use because the results are not comparable.It depends on several factors that have too many sources of error to compare better values. On my youtube channel I have made an example video. With the same knife you can compare values from 50 to 120 bess. This device is great but only to test yourself. Comparing with others is very inaccurate.
So it dont matter witch medium u use. Use it 4 urselve.

Hello Hanns,

It hadn't occurred to me that speed of the sharpness test could affect the BESS reading so I found your video demo interesting too.

However variations in the tension of the test media in the holder could also contribute to wide ranging results you observed. To rule this out you ought to ensure the media tension is the same in each test. SharpCo, another forum member, demonstrates in this video (https://www.youtube.com/watch?v=PxDYqJibMz8) how to do this.

I'd be interested to see you rerun these tests again to compare the scores you get.

Regards, Andrew

Title: Re: Positive or negative smoothing
Post by: Hannsi1957 on July 19, 2020, 01:58:34 am
@ Andrew

watch at 1 minute i use before each test on the Bess a clamp with a 100 gramm weight on it to have always the same tension.
i saw this at sharpco`s site and use it since then because it was logic 4me to do that and eliminate another error source.
if u watch at sec. 45 u will see
https://www.youtube.com/watch?v=yO7m-h-oOCQ&t=43s

the whole measurement has physically something to do with the inertia of the mass. therefore you will get different results depending on how fast you press.

cheers Hanns