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Stropping Killing Edges

Posted by jasonstone20 
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Stropping Killing Edges
June 21, 2016 05:36PM
With the Wahoo Killer knife from BUDK( I have 3 of them), these knives sharpen very easily to a very high sharpness with inexpensive/simple hones. But it you strop the knife, even with a freshly cleaned, loaded, and hard backed strop along with a compound designed for knife sharpening (Flexcut Knife Strop, Gold Compound), the edge gets killed 9/10 times. I have tried lower angles, matching angles, high angles stropping, nothing helps. Now I usually don't find a need to strop to get a 3*90° push cutting phone book paper x-grained edge, head hair whittling (HHT 2-3, 3, 3-4), but sometimes to increase polish, or for fun, or to get extreme or enhance push cutting ability, I will strop 2-3 passes per side. With the Wahoo Killer, all three of them, it's very difficult to strop on a leather, compound loaded strop, and not degrade the edge. Could it be because of the HT or low HRC?

Also, has anyone seen improvements with stropping on plain cardboard Ernest Emerson style? [emersonknives.com]

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Edited 1 time(s). Last edit at 06/21/2016 05:56PM by jasonstone20.
Re: Stropping Killing Edges
June 23, 2016 04:19PM
Quote
jasonstone20
Could it be because of the HT or low HRC

Good question, and if the answer is yes, what does that say about stropping considering you can get these knives very sharp, very easily, without stropping.


Chumgeyser on Youtube
E-nep throwing Brotherhood. Charter Member
Re: Stropping Killing Edges
June 23, 2016 10:18PM
I like the knife and the steel how it is, I find it interesting that it can get very sharp and stropping, even minimally with a clean strop and fresh compound, can kill the edge. You're right, it does say a lot about stropping in general.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Stropping Killing Edges
June 24, 2016 12:23AM
Remember which forum this is guys, we need to form a decent enough hypothesis for what is happening at least. Now, I know you don't have an electron microscope, if only we were in an ideal world, but try and figure out what is happening. Is it merely rounding of the edge and loss of cutting agression or are you managing to abrade the knife enough that it's like you are effectively running the apex through a stone?
Re: Stropping Killing Edges
June 24, 2016 12:29AM
Jason, after you strop a Wahoo Killer can you detect any hint of a burr?


Chumgeyser on Youtube
E-nep throwing Brotherhood. Charter Member
Re: Stropping Killing Edges
June 24, 2016 12:42AM
What do you mean "gets killed".
Re: Stropping Killing Edges
June 24, 2016 04:22AM
Cliff,
Going from push cutting at a 3*90° (or close as I can get) cross grained to only being able to slice cross grain and push cut with the grain.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
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me2
Re: Stropping Killing Edges
June 24, 2016 08:21PM
Do you get the same rapid degradation if you do any sort of light cutting? My thinking is steps are not overly abrasive. If you get the same sort of drop from cutting 1 out 2 passes in cardboard, it's probably not stropping that is the issue. If however you can cut for a while and that rapid drop only happens after stropping, then that likely is the cause, we just need to figure out why.
Re: Stropping Killing Edges
June 24, 2016 09:18PM
Luisknivacc,

It acts like its rounding the edge and reducing cutting aggression.

Chum,

No detectable burr after stropping.

Chris,

No issues in losing the edge in cutting, I use it as a desk, utility, and a kitchen knife.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Stropping Killing Edges
June 24, 2016 11:57PM
Hi ,
what is the "hard" backing you're using?
how thick do you rub the compound on the strop?

____
Thanks
I don't mow smiling smiley
Re: Stropping Killing Edges
June 25, 2016 12:09AM
ShaperAndMower-
The FlexCut Strop is a thin piece of leather on a piece of wood, with the rough side (suede) used for the stropping. I usually but a good amount of compounds as recommended per instructions of the strop of the FlexCut Gold Compound (when the rough leather starts to take the color of the compound).

[www.cliffstamp.com]

I have also use cardboard on a tabletop, with either Enkay Green, White, or Blue compound, alond with trying Mother's Polish on cardboard or denim.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Edited 1 time(s). Last edit at 06/25/2016 12:14AM by jasonstone20.
Re: Stropping Killing Edges
June 25, 2016 12:43AM
To clarify, with other knives with the same angle and initial sharpness, the sharpness goes up after stropping with the same strops/method?
Re: Stropping Killing Edges
June 25, 2016 02:37AM
Cliff-
Yes, it increases push cutting sharpeness slightly, without noticeable difference in slicing aggression. This is why I was puzzled what was going on with the knife/steel. I really like the knife, and for $3 it's hard to complain.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Stropping Killing Edges
June 25, 2016 12:59PM
It could be an issue with the grindability, do you have a moderate hardness, carbon steel? A Mora in 1095 or similar?
Re: Stropping Killing Edges
June 26, 2016 07:29AM
Cliff,
Yes, a few of them, and one in stainless.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Stropping Killing Edges
June 27, 2016 02:15AM
Quote
jasonstone20
But it you strop the knife, even with a freshly cleaned, loaded, and hard backed strop along with a compound designed for knife sharpening (Flexcut Knife Strop, Gold Compound), the edge gets killed 9/10 times.

Jason,

One factor worth considering is that those knives are likely to be fairly soft steel, thus typical stropping compounds are likely to eliminate most or all of the slicing aggression of the apex almost instantly.

if you happen to have a 10+ micron stropping compound, I would suggest trying that and seeing if the results are any different, at least to rule out that factor.
Re: Stropping Killing Edges
June 27, 2016 02:22AM
video: [youtu.be]

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Resident Emerson Fanboi

Folding knives are fun, fixed blades are important.
Re: Stropping Killing Edges
June 28, 2016 12:58AM
To me stropping is like a high polish edge: It might look impressive cutting thin paper, but it typically is not a contribution to edge aggression on deeper and especially yielding materials... I haven't used shaving as an edge testing method in twenty years, and phonebook paper is only for an indication of the continuity of the apex condition... The real edge aggression I determine by touching with the thumb (after rubbing with the nail beforehand to touch up and eliminate any micro-folds), continuity of the apex comes next with cutting phonebook paper, and finally I check the geometry against the light, and I really have never found anything that does better than those 4 steps...

Gaston
Re: Stropping Killing Edges
June 28, 2016 01:22AM
Well, I had a few different purposes for this post. One was to show that you can mess up an edge even with proper stropping technique if the knife has certain properties. Another was to see if anyone else had seen similar problems. Also, to see if there was a workaround, just as an interesting problem. And to see if I could verify that the grindability and low HRC could be causing the issue. Finally, that some issues people might have with a knife is not it's price or quality, but using what works for that knife specifically. The knife is very easy to sharpen, and takes a head hair whittling edge freehand, on low to medium grit hones.

Thank you everyone for your input!

I

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Stropping Killing Edges
June 28, 2016 01:52AM
Steel_Drake,
I don't have any compounds rated at 10+ micron, I do have SiC Wet/Dry (60-2500#) papers and 3M polishing cloths (30u-1u), along with miscellaneous reclaimed stone slurry. I usually use Enkay White, Green, or Blue, FlexCut Gold Compound, and I have Mother's Metal Polish along with a few tubes of MetalGlo.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Edited 1 time(s). Last edit at 06/28/2016 01:53AM by jasonstone20.
Re: Stropping Killing Edges
June 28, 2016 03:55AM
Update-
Steel_Drake's post made me think about testing how (strop type, medium, and abrasive) and when (how many passes per side) the edge became rounded. Well, I tried Mother's Mag & Aluminum Polish on demin (jeans with a board inserted in the leg) and I went all the way up to 10pps (I just stopped because that's nore than I ever strop knives) without the edge suffering loss in performance, in fact, the edge polished up nicely and push cutting was refined. I will try this test with the other methods and abrasives and see what the knife doesn't like.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Stropping Killing Edges
June 28, 2016 03:28PM
Jason,

It gets even better with coarser particulate abrasives. You can get a 10 micron diamond paste off of Ebay for cheap and spread it on a fairly compressible leather bench strop and try that on a few knives as well. At 10+ micron grit size you still get extremely high push-cutting sharpness, but without the chance of eliminating slicing aggression.

Actually, the even that really tipped onto exploring coarser particulate abrasives was when I noticed that my knives in steels like CPM-M4 were not losing slicing aggression after 5-10 passes per side on fine particulate abrasive loaded strops, but my 1095 type steel knives were losing almost all slicing aggression after 5-10 passes per side.

It was the difference in response between CPM-M4 and 1095 that led me to think that abrasive particle size was a major factor in the effect, and eventually led me to presently using 30 micron CBN emulsion on suede for creating and maintaining micro-bevels. Even with a 30 micron particulate abrasive, the resulting apex finish with still trivially push-cut newsprint at 90/90/90, even after having been touched up on the strop repeatedly between uses.
Re: Stropping Killing Edges
June 28, 2016 05:07PM
Steel_Drake,
Interesting....But at 10-30 micon, why not just use a stone? Is it to create or induce micro-convexity? Clean up any possible burr?

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Stropping Killing Edges
June 28, 2016 05:22PM
Quote
jasonstone20
Steel_Drake,
Interesting....But at 10-30 micon, why not just use a stone? Is it to create or induce micro-convexity? Clean up any possible burr?

Jason,

I've found that I simultaneously get higher push-cutting sharpness while also retaining more slicing aggression, and also at least equal high-sharpness edge retention using this method to create convex microbevels compared to microbeveling with solid sintered ceramic abrasives (e.g. Spyderco F), as I did previously.

Also keep in mind that particulate abrasives on pliable substrates act much much finer than their grit rating. I would compare the apex finish left by 30 micron CBN emulsion on suede strop to something akin to a ~4k-5k waterstone, and the finish left by 16 micron CBN emulsion on suede to that left by my Naniwa Junpaku (aka 'Snow White') 8k stone. Keep in mind that if you are buying an inexpensive diamond paste to try this out, I would advise 10-20 microns max as the grading on those products is less stringent, and the paste suspension does not embed as deeply into the substrate as liquid emulsions do (i.e. 10 micron diamond paste will act more like 15-20 micron CBN emulsion).
Re: Stropping Killing Edges
June 28, 2016 05:36PM
Steel_Drake,
That makes sense, I didn't think of those things. Thank you for the input, it helps a lot.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Stropping Killing Edges
June 30, 2016 01:38AM
Update-
Ok, now I am officially confused.....I re-sharpened the knife, using C, F, XF EZE-Lap diamond hones, and micro-beveled with a Spyderco Medium Rod, then stropped on the FlexCut strop with FlexCut Gold compound, intending to induce the same failure I had previously experienced, but that's not what happend. The knife sharpened fine, and the strop just refined the edge, just like on the denim and Mother's M&A polish. I even tried to kill the edge of the knife, using a little pressure, and a higher angle, and nothing. I have sharpened this knife probably at least a dozen times(if not twice that), it's one of the knives I use for practice, and stropping always ruined the edge. ??? confused smiley

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Stropping Killing Edges
August 03, 2016 05:39PM
Well, trying out a new stropping compound, (Woodstock Extra-Fine Green, D2902) and I managed to kill the slicing aggression on the Wahoo Killer knife with about 3 passes per side. It would still shave. I will see if I can duplicate what I did.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Stropping Killing Edges
August 03, 2016 06:40PM
Edit-
I stropped on cardboard when it killed the slicing agression, and brought the slicing agression back with a Smith's Soft Arkansas stone. Then I stropped on MDF with the Woodstock XF green, and no problem.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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cKc
Re: Stropping Killing Edges
August 05, 2016 11:07AM
Quote
jasonstone20
Steel_Drake,
Interesting....But at 10-30 micon, why not just use a stone? Is it to create or induce micro-convexity? Clean up any possible burr?

One simple reason is that when knives are ground convex, there is a much higher chance of lack of uniformity along the bevel. you then also have flat grinds which may not be uniform across the bevel, and so even with an edge bevel ground in, it may not be perfect.. small recurves, or small exposures..

when you sharpen such a knife on a stone, you will have voids, or you will grind a lot of life off a knife cleaning it up and evening out the edge.

with sandpaper and a softer backing, it will just blend in and conform to the slightly off profile and shape and you can use your knife to your hearts content not caring about these small bits..

if you are grinding distal tapered near zero ground knives which are a true distal taper with a constant change in angle on the primary bevels, then you can't just run your blade over a stone too easily to maintain that profile.. you have to flex and bend it to the stone.. in these cases I find paper over hard leather a better way to clean up such knives also when thinning by hand and repolishing.

there is also sheer laziness.. I find it so much easier to whip out a brand new piece of silicon carbide paper over leather and then strop compared to cleaning and maintaining a stone.. Although for the last few years I have not done that just because I like to experiment.. but personally.. i prefer convex, and prefer that method over flats and stones.

----------------------------------------------------------------------
It's not Cliff, its Dr Stamp
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Re: Stropping Killing Edges
August 05, 2016 04:35PM
cKc-
Interesting....I think that is a easy way for people to learn how to sharpen their knives, and it's almost foolproof, and SiC Wet/Drycan cut most cutlery steels. What stropping compounds have you tried out? What do you have available to you? For a good mix of polish and cutting, I like Enkay Green, Flexcut Gold, Woodstock XF Green D2902 and Woodstock Red D2901.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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