Wire Edge Prevention

[EOU]

Thanks for the report KG. We have a question; your post says "While his own knives last through 4-5 steer carcasses (with steeling), our test knives lasted for 2 carcasses and performed well, though for a shorter period." Did he steel the knives provided by you as well?

[KnifeGrinders]

Thanks for the report KG. We have a question; your post says "While his own knives last through 4-5 steer carcasses (with steeling), our test knives lasted for 2 carcasses and performed well, though for a shorter period." Did he steel the knives provided by you as well?

Yes.
The knives I gave him are the same as his, only new, and he steeled them as he usually does, using his polished and fine-cut steels after approx. every 10 cuts.
His steeling reflexes are set to a different edge angle though, and with our low angle of 12 dps he must have been oversteeling the apex on our knives, and this might be contributing to them wearing quicker.

Anyway, I know I have to shorten the time the edge contacts the felt wheel rotating at high RPM, and seem to have found a solution by a small modification to the horizontal platform.

We are lucky we met this butcher as he can clearly explain what is wrong and what is good, and we've improved our sharpening working with him.
The very first knives we sharpened for him he discarded in the beginning of a boning session because of the wire edge and started me thinking about it 

So for the next boning our butcher will get 2 identical knives from us: one deburred on a felt wheel run on the half-speed grinder at ~1400 RPM, and the second deburred on the same felt wheel run on Tormek at 90 RPM, not knowing which is what - if the knives show no difference between themselves but dull quicker than his own knives, then it must be due to his steeling.

Thinking of steeling, it poses a significant effect on any change to knives one may plan in an established meat processing environment.
We know that their knives will perform better at 12 dps than the 20 dps they sharpen their knives at now, but suppose one day we sharpen all knives at a meat plant at 12 dps. Because they've been steeling their 20 dps knives for years, all operators will continue steeling the new 12 dps knives at the same 20 degrees angle as their muscle memory and reflexes can not change in one day. This steeling may kill edge in all available knives and cause a disruption to the production.
Another example - and this one is not a hypothetical supposition, but a real situation we've encountered - to improve edge holding, a pilot group of operators were given knives made of a harder steel. These knives were sharpened at the same edge angle as all knives in the plant. But because the operators use frequent grooved steeling on their softer steel knives, they continued it on the new harder knives - and the wear of the edge from the grooved (fine-cut) steeling zeroed advantage of the new knives. To see positives and savings from using the harder knives operators must be re-trained to increase ratio of smooth/polished steeling vs grooved on the new knives, but we all know that the most difficult change to make is behavioural.

[SteveG]

KG,

  First, thank you for all of your excellent work and reporting, you’ve been a great help to me (and I’m sure several others) in my never ending quest to improve my sharpening.

  If you don’t mind, I have a couple of questions for you:

  1.  Did you happen to get a before/after BESS score for the butcher experiment (apologies if you already stated it - I didn’t see that in the thread).  I’m very curious as to at what point they considered the knives not fit for use.

  2.  My knife sharpening is mostly of relatively hard, carbide-heavy steel.  What I’ve been doing to ensure the burr is really removed is to place the blade on a brass plate, edge straight down (i.e., blade perpendicular to the plate), and rolling the blade from heel-to-toe applying moderate pressure (maybe a pound or two) - no slicing motion, just a rocking motion.  If the blade has the same before/after BESS, I’m assuming no burr.  Do you (or does anyone else) think that’s a safe/unsafe assumption?

  Steve

[grepper]

"What I’ve been doing to ensure the burr is really removed is to place the blade on a brass plate, edge straight down (i.e., blade perpendicular to the plate), and rolling the blade from heel-to-toe applying moderate pressure (maybe a pound or two) - no slicing motion, just a rocking motion."

Hmm…  That’s a very unique method to test for the existence of burr.  What before/after sharpness readings do you typically see when performing that test?

[KnifeGrinders]

Hi Steve,

BEFORE - both knives 70 BESS

AFTER:
VINCTORINOX NSF 5.6603.15 = 595 BESS
SWIBO 5.8405.16 = 465 BESS

I am really curious about your brass plate test for the high-Carbon knives - so if deburred OK you see little or no change in the BESS score.
Could you give an example of the blade steel please?
And how did you arrive at this test, what made you think of it?

This may be the missing test I am looking for for the high-end blades, as even with the wire edge they keep scoring excellent sharpness on the tester, unlike low-end knives.

It will be easy for me to modify the SET edge rolling tester into the wire edge tester by replacing the steel linear bearing with a section of a copper pipe and changing the impact angle to perpendicular - standard impact weight is 150 g, and I can keep loading and checking the score to find out the safe load that can show the presence of the wire edge but still not damage the apex.

Just could you tell us more of your experiences with this brass testing?

[SteveG]

"What I’ve been doing to ensure the burr is really removed is to place the blade on a brass plate, edge straight down (i.e., blade perpendicular to the plate), and rolling the blade from heel-to-toe applying moderate pressure (maybe a pound or two) - no slicing motion, just a rocking motion."

Hmm…  That’s a very unique method to test for the existence of burr.  What before/after sharpness readings do you typically see when performing that test?

When all goes well, they’re the same.  Today I did an LC200N blade; didn’t get great results, but it was 120 before/121 after, so pretty sure there’s no burr.

[KnifeGrinders]

Very interesting.
Could you tell us the range or an example of the BESS score worsening telling that a micro-burr is present?

[SteveG]

Hi Steve,

BEFORE - both knives 70 BESS

AFTER:
VINCTORINOX NSF 5.6603.15 = 595 BESS
SWIBO 5.8405.16 = 465 BESS

I am really curious about your brass plate test for the high-Carbon knives - so if deburred OK you see little or no change in the BESS score.
Could you give an example of the blade steel please?
And how did you arrive at this test, what made you think of it?

This may be the missing test I am looking for for the high-end blades, as even with the wire edge they keep scoring excellent sharpness on the tester, unlike low-end knives.

It will be easy for me to modify the SET edge rolling tester into the wire edge tester by replacing the steel linear bearing with a section of a copper pipe and changing the impact angle to perpendicular - standard impact weight is 150 g, and I can keep loading and checking the score to find out the safe load that can show the presence of the wire edge but still not damage the apex.

Just could you tell us more of your experiences with this brass testing?

Thanks for the BESS scores, that's informative.

Yes, if ok little or no change.  I haven't seen a significant change yet, but need to test when I know I've left a burr, so it's far from conclusive at this point - I only started doing this a few days ago.

What made me think of it is your results with soft steel on just the BESS media, which is something I've seen myself.  I just wanted a similar test for harder steels, since sometimes I get hair-whittling edges that don't seem to last very long, so I figured it was the burr doing the whittling.  I think I'll try it on S90V tomorrow, and intentionally leave a burr on one try, and then do a second test where I think I've removed the burr.  I replied to grepper's question with the details of today's test.  I did one yesterday on M390, but it wasn't freshly sharpened, just freshly stropped (I wanted to see if stropping was creating a burr), and the before/after were the same (I forget what they were, but in the 80~90 range).

I didn't realize that the SET had a steel roller, that's interesting.  That's a much more precise and repeatable method than what I do.  You'd know much better than I whether a soft metal would be better for burr detection than the steel, so I'll be very interested in hearing what you discover.  I'm really just looking to find out whether I've left a burr that I can't see with a microscope, since my sharpening results are inconsistent.  If there's anything specific you'd like me to try or report, let me know - I have a lot of different steels, and some decent sharpening equipment - since you provided the idea I'd be happy to provide some labor.

[KnifeGrinders]

Conventional methods of micro-burr detection don't really work on high-end edges. We have to invent a test for them.

[Ken S]

KG,

Someday your last sentence will read, “We had to invent a test for them”.

Impressive work.

Ken