MagnaCut passaround [LIVE]

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So, I have here a knife which is approximately 0.9mm at 5mm behind the edge. To demonstrate solidarity I am planning to thin it on stones: SG220 etc. I think I have enough thickness here that I can plan on having a proper hira and shinogi when I’m done, with a bit of hamaguri convexing. Does that make sense? First time thinning this much.
 
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So, I have here a knife which is approximately 0.9mm at 5mm behind the edge. To demonstrate solidarity I am planning to thin it on stones: SG220 etc. I think I have enough thickness here that I can plan on having a proper hira and shinogi when I’m done, with a bit of hamaguri convexing. Does that make sense? First time thinning this much.
Shatpon glass may not release enough abrasive. If its the magnacut blade Though idk, ive only used shapton pro.

Even. If it doesnt, it will still work. Just slower.
 

Delat

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Part 2: Thinning & Sharpening

Sharpening Magnacut with traditional stones SIC or AIO isn’t something, I could in good conscience recommend. Above 500 grit or so I think these stones are painfully slow at best and overall useless at worst. I consider myself a decent sharpener and could not achieve a clean apex off a Shapton Glass 2k even with a diamond loaded leather strop to aid burr removal.

You made me feel much better after my total failure to get a decent edge with an SG4000.
 
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I’d hoped to redo the finish, but I think it best for me to use the knife today and tomorrow and send it on its way Friday.
Hey man, you’re making some really useful discoveries here… if the altar of polishing science so demands, please feel free to hold on to the knife for longer. Everybody will understand if you need more time to finish.
 

ian

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Hey man, you’re making some really useful discoveries here… if the altar of polishing science so demands, please feel free to hold on to the knife for longer. Everybody will understand if you need more time to finish.

Heh, either you’re misreading the subtext, or this is a quality joke. I approve.
 
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@ethompson Thank you for sharing. After what you experienced, what specific stones would you recommended for thinning and sharpening magnacut?
At the recommendation and help of @SolidSnake03 I got a set of the Nano Hone diamond resin plates. The feel is odd, but I the speed and consistency is great for thinning work. Very, very strange feedback in sharpening, but they got the job done. For sharpening any diamond or CBN stone should do the trick I imagine.
 
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Just updated my thoughts in part 2, part 3 to come tomorrow evening or Friday morning.
Thanks for the detailed writeup... I feel a lot better about my bad results earlier.

I am interested to hear that you had some success (or not a complete failure anyway) with a Belgian Blue. I had the thought that the garnets may be hard enough to be useful and in terms of tactile feedback I got sense it was making some progress. Would you use one as a finisher/maintenance stone on MagnaCut or still recommend a high grit diamond stone?
 
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Thanks for the detailed writeup... I feel a lot better about my bad results earlier.

I am interested to hear that you had some success (or not a complete failure anyway) with a Belgian Blue. I had the thought that the garnets may be hard enough to be useful and in terms of tactile feedback I got sense it was making some progress. Would you use one as a finisher/maintenance stone on MagnaCut or still recommend a high grit diamond stone?
With a little forced slurry, I felt like I was making slow, but real progress with the Belgian Blue in terms of refining the bevel. I think it could be happily used a maintenance stone or finisher. I would still prefer a diamond stone for that task, however.
 

sansho

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nice review, @ethompson

maybe a new breed of synthetic 'play stone' is needed
imagine relatively soft brick that gets real muddy. filled with a mixed range of fine cBN particles... and geosmin. :upsidedownspin:
 

ptolemy

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I wonder how those chinese DMD resis diamond stones are on it
 

zizirex

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Funny, I have his Magnacut, yet I still have to make a nice edge on my Suita. it does hold an edge on light kitchen works, but it's not super hard to sharpen and mine is a workhorse ground.
 
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You made me feel much better after my total failure to get a decent edge with an SG4000.

Digging more into this:

Sharpening a carbon steel knife, we can get a sharp edge even off #200 grit. However, a knife made of wear-resistant alloys, we have to apex on #1000, and then polish and polish through a sequence of progressively finer diamonds/CBN; you cannot get a lasting sharp edge on these premium steels off the #1000 - you need a finer grit than that, much finer.
If you don’t have coarse diamond or CBN, it is OK to grind bevels of your wear-resistant blade with a coarse silicon carbide abrasive; however, setting the edge apex and honing must be done with diamonds/CBN for the lasting sharp edge. From the #1000 and finer must be diamonds or CBN. Honing the wear-resistant edge with conventional compounds, including fine ceramic hones, is the main cause of them dulling early – if you use them on your high-end knife, it may perform even worse than a mainstream knife.
See our research “Edge Rolling in High Vanadium Knives Sharpened with Aluminium Oxide versus CBN/Diamond” in the Edge Stability Testing section on our website.
 
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Sharpening a carbon steel knife, we can get a sharp edge even off #200 grit. However, a knife made of wear-resistant alloys, we have to apex on #1000, and then polish and polish through a sequence of progressively finer diamonds/CBN; you cannot get a lasting sharp edge on these premium steels off the #1000 - you need a finer grit than that, much finer.
This is simply wrong as can be seen from all of Larrin's testing, Shawn's testing and many others that test cutting on rope, cardboard, etc. Most use relatively coarse finish 400-600 grit and clearly show longer lasting edges on high wear resistant steels.

They also claim that it is a rolling test, so it is odd not to standardized for hardness, since it seems that strength/hardness would be the main contributing factor in such a test, assuming same geometry of course. The assumption is also that the blunting is from plastic deformation, rolling, but how do they determine this is what caused blunting and not microchipping for example, they don't indicate that they actually looked at the edge under a microscope.
 

HumbleHomeCook

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This is simply wrong as can be seen from all of Larrin's testing, Shawn's testing and many others that test cutting on rope, cardboard, etc. Most use relatively coarse finish 400-600 grit and clearly show longer lasting edges on high wear resistant steels.

They also claim that it is a rolling test, so it is odd not to standardized for hardness, since it seems that strength/hardness would be the main contributing factor in such a test, assuming same geometry of course. The assumption is also that the blunting is from plastic deformation, rolling, but how do they determine this is what caused blunting and not microchipping for example, they don't indicate that they actually looked at the edge under a microscope.

Agreed. My K390 cardboard slayer never goes above 600 and often stays at 300.
 
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