Dual grit testing !

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old4570

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Ok , dual grit testing is about to start :
Dual grit looks to be worth experimenting with if the results By Homeslice can be replicated ..
Just cos one person can do it ! Don't mean everyone can do it ! ( Facts of life )
And I will not be replicating the Homeslice edge , no no no ! I will be using a guided knife sharpening system .
I will do one side ( Guided ) 250 and the other side 1000 . And I will be working towards the blade and not away from the blade ( Like Homeslice )
If the results are poo ! Then I might try sharpening away from the blade to see if there is a marked difference .
I have ordered some courser diamond plate , to see how the hand sharpening goes .. ( I have nothing bellow 600 grit ) ..
So yeah ! It's dual grit playtime ...

I did buy a Spyderco Mule in CPM SPY27 for edge testing , but Huston ! There is a problem ! ( It's too damned good )

SPY27
Guided edge - 500
60 grit grind ( wet stone grinder ) 1150
80 grit grind - 950
That's a lot of rope the SPY27 is eating ! So I chose a few more ( average ) knives for testing ..

IXL ( Japan ) Lock Back from ? ( 80's maybe ) These were cheap as chips back in the day .
Guided edge - 200 Roll
80 grit grind ( Toothy ) 350
Dual Grit 240/800 ... 450
Dual Grit 400/800 ...200Roll
240/240 ... 900 ( No Fail )

Dozier D2
300 Guided ?
60 grit grind 550
Dual Grit 240/800 ... 900 Roller

Mtech MT-987 3cr13mov
Factory - 200
Regrind ( ? grit ) 350 Was it the factory 220 grit wheel ?
Dual Grit 240/800 ... 750 Roller (?)

What we have is some numbers to compare to + various steels ..

The IXL will be the first knife to be dual gritted ! 240 one side and 1000 the other ..

 
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Ok ......... I don't have 1000 grit stone / diamond for the guided sharpener ..
I have 400 / 600 / 800 / 1500 / 2000 / 2500 / 3000 and lower ...
Oh dear , just ordered some 1000 grit .
But till then the closest is the 800 grit ..
240 grit / 800 grit dual grit edge completed .
240 seems too coarse ? I might try 400 / 800 later .
 

240/800 dual grit = Stupid Toothy !
Honestly , would need to be stropped hard to smooth it out .. But as was , toothy as all !
Next I have to try 400/800

The result ? It was just so toothy ..
Honestly from about 100 slices to the 450 finish , I could not feel the difference slicing rope , it just felt the same .
And on paper , it was hard cos even the un used edge would just tear paper like an Olympic Champion .
And any fatigue / a crease / or moisture and the paper would tear . ( It was stupid hard )
Anyways .... As best as I could call it , a 450 fail . That's 100 slices over the 80 grit grind . ( Almost 30% )
Guided ...200Roll
80 grit ...350
240/800 ...450
400/800 ...200Roll
240/240 ...900 Did not fail ... I stopped !

Next 400/800 Dual Grit
 
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400/800 dual grit ! = Smooth & No gains at all - Zero / nothing / nada / zip / bubkus ...
Same as a guided / polished edge / performance or a 200 roller . Interesting .
So where do we go from here ?
How about just a 240 grit edge ( both sides ) ? Since we are testing ..
 
The next edge will be :
240/240 as a control ..
It is again just stupid toothy !
It feels like dragging a wood saw across the paper !
But , that's what testing is about . Got to test those variables ..
+ The steel on the IXL is ??? ( Good / average / poor ) Toothy at the very least !
 
Oh dear oh dear oh dear !
Single grit just kicked dual grit to the curb and Murdered it !

So , off recently ! Some fuss has been made of dual grit sharpening !
I am testing this my way . I am not trying to replicate some one else's edge or method of sharpening .
But still , I think it is worth exploring .

For a long time now I have proven to myself , that a coarser edge can improve edge retention in most knives .
This is not always the case due to those nasty Variables .
But most of the time I have seen an improvement in the 50% to 100% range ..
And those percentages ( for me ) are worth while performance gains ( as opposed to losses - Who wants to lose edge retention ? )

Anyways : 240/240 or single grit sharpening with a 240 grit diamond sharpener @ factory bevel angle .
I stopped cutting rope when the result was overwhelming ..
Oh sorry , what's overwhelming about 240 besides the Super Toothy edge = 900 slices without a fail ! I just stopped ..
So I stopped with a 100% gain over dual grit !

I have no idea in regards to the steel on this IXL , ( Good / Bad / Ugly ) .. But 900 slices is ............... 900 slices .
This edge is horrendous on paper , so if you love slicing paper - you'l hate a 240/240 edge ...
On the other hand , if you slice meat .... You might love the 240/240 edge .. Not for me to say . But I will say , it did slice a pile of rope . Not the easiest slicing , but it did slice consistently ( Took more energy from the user ) .
Might be the sort of edge you put on a Survival knife or on a knife you were taking with you to be on Alone !
Anyways , this is just knife no1 in the dual grit edge testing .. Knife no2 next !

 
Do you reckon a toothier edge to be better for other mediums such as wood, as well?
 
That is quite possible ... ( Not guaranteed - but very likely as the rope is quite abrasive )
The actual result - Came as quite the surprise ... And we are only one knife down with a unknown blade steel .
But hey , what a shocker of a result hu ?
 
KaBar Dozier D2
240/800 & stropped
Much , much smoother than the IXL thru the paper ( better steel )
 
Ok , ..........
A) Wow , looks like I have burned thru 50 meters of rope in a hurry this year ..
B) The dual grit edge did improve on ......
Dozier D2
300 Guided ?
60 grit grind 550
240/800 ... 900 Roller ? ( Stropped Back )

? Watch the video and call it yourself ..
But I called it @ 900 slices ..
It was certainly being difficult ( toothy ) , and even the unused portion of the blade was tearing paper ! ( Oh those trials and tribulations ) .
Anyways .. No matter how you look at it , the dual grit edge improved edge retention .
And so far , it looks like the better the blade steel , the better the improvement . ( how much better = You decide for yourself - why I post video )
This testing is about dual grit ... Could the 240/240 single grit murder the dual grit once more with the D2 ? ( My hands hurt , so maybe another time - this is about dual grit after all )
Will have to revisit the Uber coarse edge another time .. ( certainly seem to be good stuff on less than super steel )

 
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Here is a scientific answer to dual grit
scienceofsharp.com

Dual Grit Sharpening

A few months ago, a video was posted by Pete Colligan on his Cedric & Ada YouTube channel demonstrating the enhancement in edge retention of a knife sharpened by a novel technique, where one si…
scienceofsharp.com scienceofsharp.com
 
badige said:
Here is a scientific answer to dual grit
scienceofsharp.com

Dual Grit Sharpening

A few months ago, a video was posted by Pete Colligan on his Cedric & Ada YouTube channel demonstrating the enhancement in edge retention of a knife sharpened by a novel technique, where one si…
scienceofsharp.com scienceofsharp.com
Click to expand...
Yeah ! https://www.youtube.com/@homeslicesharpening Got me interested ..
But I did not want to replicate his sharpening method ..
I wanted to see if Dual Grit Sharpening ( as in any form of dual grit sharpening ) , in itself was responsible ..
And that looks to be the case .

I have already proven to myself that Coarse Grit sharpening works , especially with budget steels ( And I think I sort of proved it again )
I have one more knife ready to Rock N Slice Rope ... But wet weather has once again rolled in .. We had some 4 rather nice days , cool but nice .

So the conclusion so far is = Dual grit works !
And the better the steel , the better it looks to work .
Obviously VARIABLES need to be tested .. ( Time consuming ) Like 240/240 , which with the IXL kicked dual grit to the curb . ( Horribly toothy edge - but it worked )
So how about 320/320 or 400/400 and so forth .. The combinations and the different types of steels would make testing - Endless ! ( What a horrible idea )
Anyways , looks like you can use your FAV sharpening method and dual grit should see you with a longer lasting edge . ( Correct combo of grits - remembering 400/800 did nothing )
So I just need some more decent weather .
 
Old4570,

what diameter and type rope are you using?

I changed to using 3/4” Manila for testing, which more than doubles the amount of rope per cut compared to 1/2”.

Area = 3.14 (pi) x (radius squared)

1/2” = 0.196”

3/4” = 0.441”

Differences become apparent very quickly with some fine edges struggling to cut 3/4” Manila at all, while they managed 1/2” ok.

Dulling occurs far more rapidly too.

fwiw - I was sharing some results of skinning wild pigs with my Phil Wilson knives recently with Phil.

We both found that coarse edges lasted longer than finer.

I’ve gone to using skinning knives sharpened on an Atoma 140 for skinning pigs or at most a DMT 325 pocket sharpener.

If you have a chance to skin animals, especially the pigs, give it a go as differences in edges and steels become apparent quickly.

Nice videos, they are enjoyable. Keep up the good work. 👍
 
10mm Twisted Sisal .. Since I test various sizes of knives .. + The cost factor ..
Cost increases exponentially with rope DIA .
I would love to use 1inch DIA , but the cost is ............... $$
+ The more you can slice , the lower the variable . + More DIA would work against smaller knives .
It is what it is , and 10mm Twisted Sisal should be easy to procure anywhere ( I think ) and not be cost prohibitive .
So for comparison .. If say some one in Timbuctoo wanted to test their edge as a comparison , the result should be ball park ( still , those variables )
 
Mtech MT-987 3cr13mov
Factory - 200
Regrind ( ? grit ) 350 Was it the factory 220 grit wheel ?
Dual Grit 240/800 ... 750 Roller (?)

That's just jaw dropping performance from 3cr13mov .... A 750 slice fail . With what appears to be edge roll ( or some sort of edge deformation that was corrected some what with a quick and sloppy wood strop )
Also the strop Back was strong .. So looks like dual grit also strops back well . Anyways ... That is a 100%+ GAIN on the previous best of 350 .. CrMov (?)
I will do a conclusion later , lots of number crunching to do !

 
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https://www.youtube.com/@CedricAda > Where the idea for slicing rope came from ( I thought it a great idea ) ..
https://www.youtube.com/@homeslicesharpening > Responsible for my interest in Dual Grit Sharpening .
Science of sharp - https://scienceofsharp.com/2021/06/15/dual-grit-sharpening/ - Takes a look at Dual Grit Sharpening

I did mention I had no interest in REPLICATING HomeSlice in regards to method of sharpening ..
Wanted to see if the actual Dual Grit Edge was responsible for the gains rather than the method for laying down the edge !
That's why I used a guided knife sharpener to put down a dual grit edge .. I was matching the bevel angle on the knives so as to remove a rather important variable .
This way a direct comparison could be made to previous results .

IXL ( ? Steel ) Is it some sort of 440 or 420 ? I dont know .. The blades don't seem to rust .
It saw the smallest gain from dual grit ( ? Worst Steel ? ) , but it was a gain .
Though the IXL sure did respond to the 240/240 edge ( did it ever ) . Just Uber Toothy !

Dozier D2 Not the most impressive D2 I own ..
But the knife did respond to the wet stone grinder , and responded to the Dual Grit Edge ! I mean it really reached up there and touched the performance levels of Super Steels .

Mtech MT-987 3cr13mov
This knife was another shocker .. CrMov reaching 750 ... That just blew me away . That was a over 100% + improvement over it's previous best .
Who doesn't want a 100%+ increase in edge retention ?

Strop Back - Here was another surprise , just how well the dual grit strops back . It just strops back strong .

Toothy - Yes , the softer lower quality steels will get Toothy ! I mean really toothy . If you love slicing paper , maybe dual grit is not for you . The coarse 240 really creates a toothy edge that can tear paper on a whim . But for other tasks that are not related to paper slicing , it could be the Bee's Knee's ! And harder better steels are less toothy - Still toothy , just not like a wood saw !

Experimenting - I dare say Dual Grit has earned some respect from me . And I can't help but feel it deserves more experimenting , especially with grit combinations . I had no 1000 grit diamond ( shame on me ) , but I have ordered some . So playing with the grits might be worth while , you know . To find a less toothy edge that jacks edge holding . Like maybe 320/1000 - 320/1500 - or some such ! Is 240/800 - 250/1000 the pinnacle , or is there room for more ?

Sharpening - Now ......... HomeSlice is very particular about how the edge is created .. And I wanted to do it my way to see if the method or the result was responsible for the increase . And from this limited testing it looks like the result is what counts and not the method of getting there . Which means that just about everyone should be able to try this .



IXL ( Japan ) Lock Back from ? ( 80's maybe ) These were cheap as chips back in the day .
Guided edge - 200 Roll
80 grit grind ( Toothy ) 350
Dual Grit 240/800 ... 450
Dual Grit 400/800 ...200Roll
240/240 ... 900 ( No Fail )

Dozier D2
300 Guided ?
60 grit grind 550
Dual Grit 240/800 ... 900 Roller

Mtech MT-987 3cr13mov
Factory - 200
Regrind ( ? grit ) 350 Was it the factory 220 grit wheel ?
Dual Grit 240/800 ... 750 Roller (?)
 
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It would be awesome to see pictures of the apex once you finish sharpening, to see exactly how aggressive the apex looks given different grits, and then once you finish the cut test. Would need a microscope of some sort, maybe one of the cheap digital ones available online. Just an idea, keep up the good work!!
 
Strauss95 said:
It would be awesome to see pictures of the apex once you finish sharpening, to see exactly how aggressive the apex looks given different grits, and then once you finish the cut test. Would need a microscope of some sort, maybe one of the cheap digital ones available online. Just an idea, keep up the good work!!
Click to expand...
Yeah , some one did that already ...
 
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