Nate does Magnacut

Nathan the Machinist said:
No, it wasn't. It was 20. Our standard angle is 20 for that pattern and I pulled it from a stack. Not a valid scientific test, but I didn't want to end the video on a down note and it was an impromptu cut. I was demonstrating Magna cut against some carbon steels and broke it on some bolts and I wanted to end the video on a good cut.

And then, there was a little brouhaha about cutting a chain a while back. That chain was included in a lot of grinders that I bought at an auction with an unknown background that was clean and not rusty and people, both on blade forums and Instagram, accused me of cutting aluminum or lead. So I wanted to show a rusty chain cut. I've had it sitting out in the rain for a while.

It was not a perfect demonstration but I did not enter it with the intent of misleading anyone, but these knives are normally 20 DPS. I reduced the angle to 18 for development work because it makes issues with edge stability more obvious. Delta 3V can cut a bolt or a chain at 18 DPS without blowing out. There will be a little more edge damage but it is not some kind of a threshold where things start just blowing out because the angle is a couple degrees narrower.

A flaw in the demonstration due to poor planning, not some nefarious intent.
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Thank you very much for the reply. I wasn’t implying any ill intent if that is how it came across. I assumed it would be 20 DPS since that is your normal angle for these and I figured you did just that pull it out of the pile so to speak. Just didn’t want to make an assumption without knowing just going by my hunch.
 
Nathan the Machinist said:
No, it wasn't. It was 20. Our standard angle is 20 for that pattern and I pulled it from a stack. Not a valid scientific test, but I didn't want to end the video on a down note and it was an impromptu cut. I was demonstrating Magna cut against some carbon steels and broke it on some bolts and I wanted to end the video on a good cut.

And then, there was a little brouhaha about cutting a chain a while back. That chain was included in a lot of grinders that I bought at an auction with an unknown background that was clean and not rusty and people, both on blade forums and Instagram, accused me of cutting aluminum or lead. So I wanted to show a rusty chain cut. I've had it sitting out in the rain for a while.

It was not a perfect demonstration but I did not enter it with the intent of misleading anyone, but these knives are normally 20 DPS. I reduced the angle to 18 for development work because it makes issues with edge stability more obvious. Delta 3V can cut a bolt or a chain at 18 DPS without blowing out. There will be a little more edge damage but it is not some kind of a threshold where things start just blowing out because the angle is a couple degrees narrower.

A flaw in the demonstration due to poor planning, not some nefarious intent
Click to expand...

I like hearing about angles, as the question is at what angle edge can it get through a nail, as a I think a random butter knife gets through a nail at around 30 degrees without damage.
 
Nathan the Machinist said:
No, it wasn't. It was 20. Our standard angle is 20 for that pattern and I pulled it from a stack. Not a valid scientific test, but I didn't want to end the video on a down note and it was an impromptu cut. I was demonstrating Magna cut against some carbon steels and broke it on some bolts and I wanted to end the video on a good cut.

And then, there was a little brouhaha about cutting a chain a while back. That chain was included in a lot of grinders that I bought at an auction with an unknown background that was clean and not rusty and people, both on blade forums and Instagram, accused me of cutting aluminum or lead. So I wanted to show a rusty chain cut. I've had it sitting out in the rain for a while.

It was not a perfect demonstration but I did not enter it with the intent of misleading anyone, but these knives are normally 20 DPS. I reduced the angle to 18 for development work because it makes issues with edge stability more obvious. Delta 3V can cut a bolt or a chain at 18 DPS without blowing out. There will be a little more edge damage but it is not some kind of a threshold where things start just blowing out because the angle is a couple degrees narrower.

A flaw in the demonstration due to poor planning, not some nefarious intent.
Click to expand...

Fantastic for people who don't use facetagram or instaface like myself , I'm glad you post your videos here !

Chop away sir!!
 
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Nathan the Machinist said:
I dunno. You should try it.
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There's a video out there. it's about 30 degrees, grinds it, buffs it, cuts nail, shits on the nail test, I don't want to post it, because I worry it will give the wrong idea to the people who just skim and watch the video. But the point is that it's gets very tough to cut a nail as the edge gets thinner, and as a fan and owner of your knives, they have nice thin edges. So thank you.
 
I sharpen my fixed blades to 15 to 17 dps. There are some (scandi grinds) even with 10dps. I like my cuts to be effortless and I do not mind using them carefully.

My CPKs had no use yet and they are still possessing the intendent edge angles. But I have a feeling that they would hold up great at lower angles if they are not abused heavily.
 
murat1983 said:
I sharpen my fixed blades to 15 to 17 dps. There are some (scandi grinds) even with 10dps. I like my cuts to be effortless and I do not mind using them carefully.

My CPKs had no use yet and they are still possessing the intendent edge angles. But I have a feeling that they would hold up great at lower angles if they are not abused heavily.
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When I started with 3V using the industry standard heat treat it had pretty mediocre edge stability. It was a tough steel with good abrasion resistance on paper. Being a tough steel it lends itself to hard use knives, but the abrasion resistance was not paying a dividend in this application. It was just a knife that took longer to sharpen, but it was taking edge damage from the mediocre edge stability. My work with 3V has improved the edge stability where it is now a knife that holds an edge well in rough use which was my goal, but there are other alloys that have better edge stability at narrow angles. I would say that 15 DPS is the basement. Narrower than that and I would find a different steel such as AEBL, and the higher carbon simple steels such as 52100 and W2 etc.
 
3V is a tough steel. It's not tough because of something that I did to it, that toughness is just baked in. I started with the extreme use videos to demonstrate that my tweak had not made the steel weak and fragile. It is possible to do that (a badly botched pre-quench can do that for example). I was just trying to show that my knives had improved rough use edge retention and that I had not thrown the toughness baby out with the bath water getting there.
 
Nathan the Machinist said:
I would say that 15 DPS is the basement. Narrower than that and I would find a different steel such as AEBL, and the higher carbon simple steels such as 52100 and W2 etc.
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I am not planning to go with very acute (<15dps) on my CPKs. I only do that with my slipjoint knives. I usually go 15 or lower (often 12.5) with these due the way I am using them. Probably I will keep most of my CPKs at original geometry (particularly the behemother) as they are meant to be hard use knives, even though I am not some using his knives in that way. I would take my MC DEK3 to 15dps when it comes.

I have 52100 kitchen petty knife which chips easily... It is not particularly thin either (it is 17 dps with around 10tho behind the edge). Probably a heat treatment issue...
 
murat1983 said:
I am not planning to go with very acute (<15dps) on my CPKs. I only do that with my slipjoint knives. I usually go 15 or lower (often 12.5) with these due the way I am using them. Probably I will keep most of my CPKs at original geometry (particularly the behemother) as they are meant to be hard use knives, even though I am not some using his knives in that way. I would take my MC DEK3 to 15dps when it comes.

I have 52100 kitchen petty knife which chips easily... It is not particularly thin either (it is 17 dps with around 10tho behind the edge). Probably a heat treatment issue...
Click to expand...

52100 can put too much carbon into solution if the aus time or temperature is too high, and it does not have much carbide pinning grain boundary. It benefits from descending heats before austinitizing. It's a fantastic steel with very good fine edge capabilities but the maker has to nail the heat treat.
 
murat1983 said:
Resulting with carbide growth?

Thanks for the interesting info.
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Not carbide growth but grain growth. The carbides that pin the grain boundaries are not particularly robust (they dissolve and disappear) and massive grain growth from excessive or repeated heats can create a fragile matrix. Or, you can simply put too much carbon in solution. You can temper that back, but it's better to put the optimal amount to start with. Many materials perform well with a little bit of lath mixed in with the plate martensite. 52100 has fantastic properties if done just right, but I don't think it is as simple as baking brownies. That stuff is above my pay grade.
 
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