Thinnest functional bladestock for a general use folder

[Toucan]

The ladybug, Dfly, Chappy, Centofante, etc are perennial favorites in part because the blades are so dang thin. Thin stock slices better, so I wonder if even thinner knives have a place in Spyderco's offerings. As far as I can tell, for locking folders, the thinnest available currently is 2mm. I wonder how thinner stock would perform as a general use knife.

Would even thinner stock be feasible, and if so, desirable? Spyderco has gone thinner in the past with speacialized models like the Catcherman (1.8mm, I believe), so we know it is at least feasible. I assume that 2mm is the goldilocks thinness of slicing well while not being too fragile, but is this necessarily the case? What are the limitations of ultra thin stock, and is there a market for them?

Some thoughts and limitations:

One limitation I can think of is needing more thickness on the tang where the lock interfaces. I suppose this could be remedied by machining down thicker stock everywhere but the tang, but this seems costly and time consuming.

Would the blade become too flexible or brittle? Bending and/or snapping are obviously not desirable, so I suppose the steel selection and heat treat might need extra consideration in very thin stock.

I know the obvious answer for many will be to just look at currently offered hollow grind models that are really thin behind the edge instead, but there is still something to be said about FFG when cutting through something like a carrot.

[Evil D]

Many companies have been making knives in thinner stock for practically 100 years, just look at almost anything Case makes.

[VooDooChild]

Razor blade.

[brancron]

I would be very happy to see even thinner folders. I have a .044” stock full flat ground folder in M2 by Walter Wells and it cuts like a laser.

Some of the high toughness, high hardness, fine grain steels Spyderco uses (CruWear would be a good example) can support very thin edges without undue chipping/rolling.

My firm hope is that the 2020s usher in an era of ultra-thin knives. Geometry is king!

[Toucan]

Many companies have been making knives in thinner stock for practically 100 years, just look at almost anything Case makes.

Very true, I should elaborate, I mean Spyderco in particular making locking modern folder with modern steels. There is a lot of charm to a older style slip joint pen knives with thin blades, don't get me wrong, but they tend to be made from older more economical stainless steels like 420hc or heaven forbid, 420j2. Or the occasional 10xx carbon steel out of a maker like GEC. Nothing wrong with those at all, but I'm interested in the idea of an ultra thin Spyderco with their usual assortment of specialty steels. Can an ultra slim production folder be made out of high carbide steels? The Catcherman example I mentioned is made of pretty tough H1 that has no carbides at all to speak of. Could, for example, a K390 Delica with 1.5mm stock be made, or is that just not reasonable with the properties of the material used?

Maybe a better way of phrasing all this, is is 2mm the functional limit of blade stock made of modern high carbide PM steel?

[Toucan]

Razor blade.

I see your point, but I think a razor is around 0.3mm. I was thinking somewhere in the 1.75 to 1mm range. Thin, and perhaps fragile, but not disposable.

[Toucan]

I would be very happy to see even thinner folders. I have a .044” stock full flat ground folder in M2 by Walter Wells and it cuts like a laser.

Some of the high toughness, high hardness, fine grain steels Spyderco uses (CruWear would be a good example) can support very thin edges without undue chipping/rolling.

My firm hope is that the 2020s usher in an era of ultra-thin knives. Geometry is king!

That is very thin! Is there much flex in the blade, if at all? Yes, Cruwear makes a lot of sense to me. Toughness probably becomes increasingly more important when approaching extreme geometries. I have no expertise in these matters, but it does seem that the balance of properties become much less forgiving in thinner geometries.

[ZrowsN1s]

Many companies have been making knives in thinner stock for practically 100 years, just look at almost anything Case makes.

Very true, I should elaborate, I mean Spyderco in particular making locking modern folder with modern steels. There is a lot of charm to a older style slip joint pen knives with thin blades, don't get me wrong, but they tend to be made from older more economical stainless steels like 420hc or heaven forbid, 420j2. Or the occasional 10xx carbon steel out of a maker like GEC. Nothing wrong with those at all, but I'm interested in the idea of an ultra thin Spyderco with their usual assortment of specialty steels. Can an ultra slim production folder be made out of high carbide steels? The Catcherman example I mentioned is made of pretty tough H1 that has no carbides at all to speak of. Could, for example, a K390 Delica with 1.5mm stock be made, or is that just not reasonable with the properties of the material used?

Maybe a better way of phrasing all this, is is 2mm the functional limit of blade stock made of modern high carbide PM steel?

I can answer that. In trying to make the 'Performance Delica' in K390 we were told that the maker couldn't grind the K390 that thin without issues. So it was switched to VG-10.

[JRinFL]

Dr. Larrin Thomas has hinted that MagnaCut’s formula can be adjusted to change the attributes, so perhaps we can convince him to make an adjustment specifically for thin blade stock? Otherwise, I’m always happy for more Cruwear. I think Niagara would need to roll it thinner than they do now so that knife makers would not have to grind it so much. Perhaps they already do and it just needs to ordered that way? I don’t know.

[kobold]

AEB-L was/is used for razors , so that would work here too. Also I think Rex45?

[Toucan]

Many companies have been making knives in thinner stock for practically 100 years, just look at almost anything Case makes.

Very true, I should elaborate, I mean Spyderco in particular making locking modern folder with modern steels. There is a lot of charm to a older style slip joint pen knives with thin blades, don't get me wrong, but they tend to be made from older more economical stainless steels like 420hc or heaven forbid, 420j2. Or the occasional 10xx carbon steel out of a maker like GEC. Nothing wrong with those at all, but I'm interested in the idea of an ultra thin Spyderco with their usual assortment of specialty steels. Can an ultra slim production folder be made out of high carbide steels? The Catcherman example I mentioned is made of pretty tough H1 that has no carbides at all to speak of. Could, for example, a K390 Delica with 1.5mm stock be made, or is that just not reasonable with the properties of the material used?

Maybe a better way of phrasing all this, is is 2mm the functional limit of blade stock made of modern high carbide PM steel?

I can answer that. In trying to make the 'Performance Delica' in K390 we were told that the maker couldn't grind the K390 that thin without issues. So it was switched to VG-10.

What was the nature of the issue? I do wonder if it is just not feasible to grind away that much K390 from 2.5mm stock. The K390 ladybug is already 20% thinner than the Delica, and is produced just fine. The only difference is the maker is working with stock that was thinner to begin with.

[amateur blacksmith]

Blade stock thinness is only 1/2 the story. It's the BTE tick/thinness that matters more. Hollow ground knives out perform FFG for this reason (IMHO). For me the Chaparral is a little disappointing even though it has 2mm blade stock. It needs to have more taper to the edge so it's thinner behind the edge. Yes, I too would like thinner blade stock generally but I'd prefer to see more hollow grinds to achieve the BTE thinness that performs.

[ZrowsN1s]

What was the nature of the issue? I do wonder if it is just not feasible to grind away that much K390 from 2.5mm stock. The K390 ladybug is already 20% thinner than the Delica, and is produced just fine. The only difference is the maker is working with stock that was thinner to begin with.

You may have a good point there. I believe the issue was thinning down the standard thickness stock. Obviously because of the pivot size and lock they have to use the standard thickness stock for the knife to function properly. Then grind the blade thin.

If they made a completely new design that could function with a thinner stock maybe they could take it thinner.

[Nate]

The real question may be what is the thinnest bladestock where the opening hole doesn’t become a liability? 2mm is probably close to that limit imo.

[Cadenno]

There are several factors to consider for ultra thin blades.

-The length of the blade, where a long blade risks a lot of problems of twisting and therefore breaking

-Hardening, where thin blades risk more deformation and bending in the hardening stage

-The final beveling phase that risks to lose part of the hardening on ultra thin blades

-The possibility of claims for breakage, since someone may do too heavy work for an ultra fine knife.

-etc

Personally, I prefer a knife that is not too thin, with which I can do most jobs without worrying about breakage.
And I think this is also the philosophy of a regular knife manufacturer:
"Fewer manufacturing problems, and fewer post-sale complaints, for a product that will cut fantastically anyway."

[Wandering_About]

2mm or about .080" is about as thin as I will go for a practical general use knife. The 2.5mm blade stock on a Delica seems just right for me, for a blade of that size. Very thin blade stock knives seem to be for niche uses, for me.

I would rather have 2.5mm ground thin behind the edge than thinner blade stock.

[Wartstein]

Some will already guess what comes next :

I am not necessarily for thinner blade stocks, but for making Spydie-blades with / in already existing thin bladestocks just longer
... so "Chapparra XL-ish" in about Endela size (viewtopic.php?t=85342#p1377379)

A blade with the 2mm Chaparral ffg bladestock, but just longer, would normally then get even thinner in its front part anyway due to the usual tapering.

I would not be worried using an endela-sized Chaparral or an Endela or totally new model in 2mm ffg "hard", as long as it comes to "regular" folder tasks.

(And YES, I know that thin bladestock is by far not the only factor that determines sliciness, but it is a good foundation for achieving it)

[JRinFL]

Blade stock thinness is only 1/2 the story. It's the BTE tick/thinness that matters more. Hollow ground knives out perform FFG for this reason (IMHO). For me the Chaparral is a little disappointing even though it has 2mm blade stock. It needs to have more taper to the edge so it's thinner behind the edge. Yes, I too would like thinner blade stock generally but I'd prefer to see more hollow grinds to achieve the BTE thinness that performs.

Agreed! I’ll always support more high hollow grinds. Knife makers don’t like them as they take longer and require a bit more skill than FFG.

[bearfacedkiller]

I think the limiting factor is blade flex. You want the blade thin for cutting ability but not so thin that the blade is no longer rigid.

Spyderco uses a distal taper on many knives and this allows a blade to thin towards the tip while still being rigid. It’s a great way to balance things out.

[The Deacon]

The ladybug, Dfly, Chappy, Centofante, etc are perennial favorites in part because the blades are so dang thin. Thin stock slices better, so I wonder if even thinner knives have a place in Spyderco's offerings. As far as I can tell, for locking folders, the thinnest available currently is 2mm. I wonder how thinner stock would perform as a general use knife.

Would even thinner stock be feasible, and if so, desirable? Spyderco has gone thinner in the past with speacialized models like the Catcherman (1.8mm, I believe), so we know it is at least feasible. I assume that 2mm is the goldilocks thinness of slicing well while not being too fragile, but is this necessarily the case? What are the limitations of ultra thin stock, and is there a market for them?

Some thoughts and limitations:

One limitation I can think of is needing more thickness on the tang where the lock interfaces. I suppose this could be remedied by machining down thicker stock everywhere but the tang, but this seems costly and time consuming.

Would the blade become too flexible or brittle? Bending and/or snapping are obviously not desirable, so I suppose the steel selection and heat treat might need extra consideration in very thin stock.

I know the obvious answer for many will be to just look at currently offered hollow grind models that are really thin behind the edge instead, but there is still something to be said about FFG when cutting through something like a carrot.

I love my Chaparral and would love to see more, even thinner, blades.

One way to get around the lock interface issue without the cost and waste of grinding down thicker blade stock would be to sandwich the blade's tang between two pieces of the same steel.

As for flex issues, am sure some idiot will find a way to bend one, but I've done some stupid stuff with a K04 Utility Knife without issue, and its 6.5" blade is a mere 1.3mm thick.