Magnacut

[Big John]

It really depends on how the "reprofile" is done. The knives I've seen of Vivi's have edge bevels so wide that they border on being a 50/50 bevel and blade grind reprofile, compared to using an Edge Pro to drop a bevel from 40 inclusive to 30 inclusive. Doing a reprofile the way Vivi does his will thin the whole blade behind the bevel, and to me is kinda closer to a mild convex than a lowered edge bevel.

Assuming a steady hand it's no different, the angles are just a bit more extreme.

I used to convex the bevels into the blade grind by hand and those knives cut very well. I had a ZDP189 Caly Jr ground extremely thin and convexed into the primary grind. It looked a lot different than my EDC Pacific. Tried to link some photos but they're so old they expired.

Absolutely correct. Convexing the edge bevel gets a bad rap because people assume you've convexed the apex itself, creating a bevel that starts at say 15dps and (perhaps, inadvertently) ends at 25dps at the apex. But a knife that is convexed in such a way that it begins at 8dps and ends at a perfect V at 13dps, while convexed, will be a sensational cutter. But I feel some people don't like the look of it. It's simply about smoothing out the otherwise pointy angle at the transition from the apex bevel to the primary grind.

[vivi]

Yep. They cut more smoothly in binding materials like cardboard.



Convexed CPMD2 Millie. Very thin bte.

[Josh Crutchley]

The blade never gets thicker when you remove metal. Whatever thickness the untouched portion of the blade had before you changed the bevel it will still have. I don't see how this will make cutting worse as you are already thinning out the portion of the blade that does that actual work of cutting.

The reason why cheap steak knives cut so well for so long is that they have very thin stock with parallel sides. It is almost the minimum amount of steel needed to support the edge. A slight taper towards the top would be better yet, but not enough to make the added cost worth it. FFG is a wedge and HHG is still a wedge (like a tuned axe blade), but with better performance, IMO.

Of course the blade doesn't get thicker never said it did. The BTE measurement will get thicker.

Larrin mentions in his Catra testing that BTE does have an affect.

"The edge angle can be relatively easy to change with sharpening. However, thickness behind the edge, the angle of the “primary bevel” behind the edge, and the shape of the edge can all affect the result."
https://knifesteelnerds.com/2020/05/01/ ... fe-steels/

[vivi]

I think we're just defining bte different. bte to me is right behind the apex, and the transition from the entire bevel to the primary grind seems to be what you're referring to.

modifying that transition area and the full grind can give some excellent geometry. I've messed around with that on my sander with fixed blades but have done Spydies by hand on stones so far. Like the Pacific Salt I converted to a scandi style grind.



SRK-C I reground on both the bevel and primary grind.

[JRinFL]

The blade never gets thicker when you remove metal. Whatever thickness the untouched portion of the blade had before you changed the bevel it will still have. I don't see how this will make cutting worse as you are already thinning out the portion of the blade that does that actual work of cutting.

The reason why cheap steak knives cut so well for so long is that they have very thin stock with parallel sides. It is almost the minimum amount of steel needed to support the edge. A slight taper towards the top would be better yet, but not enough to make the added cost worth it. FFG is a wedge and HHG is still a wedge (like a tuned axe blade), but with better performance, IMO.

Of course the blade doesn't get thicker never said it did. The BTE measurement will get thicker.

Larrin mentions in his Catra testing that BTE does have an affect.

"The edge angle can be relatively easy to change with sharpening. However, thickness behind the edge, the angle of the “primary bevel” behind the edge, and the shape of the edge can all affect the result."
https://knifesteelnerds.com/2020/05/01/ ... fe-steels/

Yes, I didn’t mean to imply that you thought it did. I was just pointing out that the overall thickness remains the same. The only way to avoid that is with a parallel sided blade or a full regrind as you know. Vivi’s resharpening does work to improve cutting performance which might imply that the BTE measurement concerns might be overstated.

[Josh Crutchley]

Yes, I didn’t mean to imply that you thought it did. I was just pointing out that the overall thickness remains the same. The only way to avoid that is with a parallel sided blade or a full regrind as you know. Vivi’s resharpening does work to improve cutting performance which might imply that the BTE measurement concerns might be overstated.

Yes your right it and most people probably won't notice the difference in a few thousands.

When I used and sharpened Vivi's scandi H1 I didn't use a micro bevel. So I was thinking the BTE on that was the full stock thickness. If it's sharpened with a micro bevel then it's thinner, way thinner. Things can get confusing when people define things differently.

While Vivi's Salt certainly cuts amazingly well it doesn't look as good as new . I'm able to do regrinds and change bevel angles but that's not the same as pulling a fresh Spyderco out of the box and have it cut like a laser.

All the people that use the Murray Carter method why not post some pics. Might not be as bad as I'm imagining.

[Coastal]

I'm able to do regrinds and change bevel angles but that's not the same as pulling a fresh Spyderco out of the box and have it cut like a laser.

Brand new ones do look nice, but I think the reprofiled/reground ones do too. To me, a full regrind, done well, always looks better than factory-new. As for cutting like a laser, the knives I've sharpened recently after reading the info in this forum, all cut better than my new knives.

[vivi]

Pros can make regrinds look good as new. The Krein regrind knives I used to own all looked great. I'm just a hobbyist chasing performance with little regard for aesthetics.

[Brock O Lee]

I've heard people talk about thinning edges out in many threads but no one ever posts a pic. I can see how it would help but I can't imagine it looks good. If I was going to ruin the looks might as well regrind it myself.

Convexing the edge bevel gets a bad rap because people assume you've convexed the apex itself, creating a bevel that starts at say 15dps and (perhaps, inadvertently) ends at 25dps at the apex. But a knife that is convexed in such a way that it begins at 8dps and ends at a perfect V at 13dps, while convexed, will be a sensational cutter. But I feel some people don't like the look of it. It's simply about smoothing out the otherwise pointy angle at the transition from the apex bevel to the primary grind.

Big John I think you nailed it here.

I can completely understand that many people may dislike a convex because it changes the look. Also, relatively few people are crazy enough to scratch up a brand new blade by laying it flat on a coarse stone. Once you start you have to commit and finish the process. It is a bit daunting at first, but the truth is you can remove scratches by working up with a grit progression and then match a factory satin finish to end with.

I like convexes, but I dislike that look of the transition between convex and FFG, so I "convex" the whole height of the blade, from apex to spine, and leave no bevel shoulders. Technically the thickness BTE then equals the thickness of the spine I guess... It is more work but looks better to my eye. I usually start (cheat?) with a low edge bevel off the Edge Pro. Then blend the shoulders freehand into the primary grind up to the spine, but don't touch the apex again until the end.

This Stretch a good example. The soft 420J2 steel made it easier to remove material up to the spine (Cliff Stamp once mentioned this is one reason why Japanese blades are cladded with a softer steel, for the user to be able to thin it out). This one is probably around 10 dps near the apex before I added a 15 dps microbevel for durability. No bevel shoulders to bind in materials like plastic containers or thick cardboard.


Same story with the Sage on the left:


I hope Spyderco release their Magnacut blades thinner than usual, but I doubt it. Some hard users will push it to find the limits of toughness, and I think Spyderco for that reason will leave more meat on the bone to stay on the conservative side.

[Bill1170]

I’m a huge fan of blending the sharpening bevel into the primary grind. By convexing this transition the shoulder is eliminated and the blade sails through stiff material that used to hang up on that shoulder.

[sal]

Hi BrocK O Lee,

Nice edge!

Keep in mind that it is a new steel and we've much to learn about it's abilities, edge angles, heat treat etc. I'm sure that Larrin would also appreciate any of the Real World Testing We do.

sal

[fanglekai]

because if you grind it at a thinner angle, it gets thinner.

or are you talking about behind the bevel rather than behind the edge?

I define the edge as the apex. so if I take a stock Pacific Salt and grind the bevel back to 10dps the blade will definitely be thinner right behind the apex.

We have been talking about BTE thickness. Yes if you measure the actual apex bevel it will be thinner at lower angles but where the bevel meets the the rest of the blade will be thicker.

If you measure at B the reprofiled edge is thinner. The problem is the BTE thickness has increased as A is thicker than B.

I'd imagine you wouldn't measure BTE thickness at location A, though. You'd measure it at location B (or some fixed distance up from the apex) for both grinds, and as you can see, the thickness of A is less than B at location B.

[Josh Crutchley]

I'd imagine you wouldn't measure BTE thickness at location A, though. You'd measure it at location B (or some fixed distance up from the apex) for both grinds, and as you can see, the thickness of A is less than B at location B.

"B" represents the original apex bevel to blade grind transition. "A" is the same transition for the reprofiled edge. You would have to measure the reprofiled edges BTE behind point "A". You can't measure BTE in the middle of the edge bevel. Or is there more than one way people do it? Why wouldn't there be.

[vivi]

because if you grind it at a thinner angle, it gets thinner.

or are you talking about behind the bevel rather than behind the edge?

I define the edge as the apex. so if I take a stock Pacific Salt and grind the bevel back to 10dps the blade will definitely be thinner right behind the apex.

We have been talking about BTE thickness. Yes if you measure the actual apex bevel it will be thinner at lower angles but where the bevel meets the the rest of the blade will be thicker.

If you measure at B the reprofiled edge is thinner. The problem is the BTE thickness has increased as A is thicker than B.

We're in 100% agreement, we were just working with different definitions.

The behind the bevel thickness does indeed increase when I reprofile the bevel to more acute angles.

[bluntcut]

I used apex bevel face length - at any distance between edge and bevel shoulder - to calculate BTE. Easier this way using closeup image. e.g. I added BTE at 0.2mm(hypotenuse/side) up from edge


IMO - Order of importance: angle (of cutting wedge) then BTE then primary bevel then .. until spine thickness. width/height of blade is important/relevant - overall wedging grade.

"B" represents the original apex bevel to blade grind transition. "A" is the same transition for the reprofiled edge. You would have to measure the reprofiled edges BTE behind point "A". You can't measure BTE in the middle of the edge bevel. Or is there more than one way people do it? Why wouldn't there be.

[Big John]

Yep. They cut more smoothly in binding materials like cardboard.



Convexed CPMD2 Millie. Very thin bte.

Nice edge. I've done similar things in the past and they do cut very well, and seemingly longer. And your comment reminds me of Cliff Stamp speaking on how sub par geometry (picture 25dps and THICK bte) yields a smashing effect when cutting/plowing into mediums like cardboard, which temporary makes the material more dense during the cut and applies more pressure to the apex, thus adding to steel fatigue and ultimately decreased edge retention. When I first heard him say that years ago it made complete sense, yet still was eye opening. To think, there are still relatively unexplored reasons why geometry is king.

[Brock O Lee]

Hi BrocK O Lee,

Nice edge!

Keep in mind that it is a new steel and we've much to learn about it's abilities, edge angles, heat treat etc. I'm sure that Larrin would also appreciate any of the Real World Testing We do.

sal

Thank you Sal…

I am looking forward to sink my teeth into some Magnacut soon, and to experiment with thinner edges to see what it can do. In the name of science of course (when the wife asks)!

[Josh Crutchley]

I'd imagine you wouldn't measure BTE thickness at location A, though. You'd measure it at location B (or some fixed distance up from the apex) for both grinds, and as you can see, the thickness of A is less than B at location B.

If you measure using a fixed distance behind the apex bevel to blade grind transition the reprofiled one would be thicker. When reprofiling and sharpening you're removing material from the apex. That moves the point up the blade grind. We're talking about tenths maybe a thou so it's kinda a moot point anyway. I'm just crazy.

All this talk had me really rethink how much one could really tell in such a small change. I can notice a difference of >5 thou but doubt much less.

I honestly just want thinner blades. It's soo much quicker to sharpen high wear steels when they're ground thin.

[RamZar]

The Mule Team MagnaCut was released on December 3, 2021 with a batch of 2,000 of them. So, why is the Native5 Salt MagnaCut Yellow FRN (announced in the 2022 Product Guide on December 7, 2021) taking so long to be released? Is the heat treat different between the two?

[Bemo]

That's the question isn't? Technically Spyderco was first into the market with this steel (kudo's to them for that). But my first available purchase was the Hogue Deka and a Case?! I very much trust Spyderco to get the heat treat right. But wow this is taking a long time. All I want is a Native 5 and eventually a Sage... that's it. I'd be content forever with those 2. Hey now, maybe that's the problem. I'd stop buying knives like crazy and mess with their cash flow?