4 mm vs. 3 mm, any real advantage?

[catamount]

Some have expressed disappointment that the Manix 2 XL's blade is only 3 mm thick instead of 4 mm, like the original C95. I'm actually pleased. IME, 3 mm offers advantages in slicing and ease of carry.

4 mm certainly gives the appearance and feel of ruggedness, but what real advantage does it offer over 3 mm in a folder? I'm trying to visualize a real world cutting situation where a 3 mm blade is damaged or broken, but a 4 mm one would have survived unharmed. Can anyone give an example? It seems to me that if you are applying enough force in the wrong way to break 3 mm, you are placing an awful lot of faith in that extra mm.

I'm sure some will suggest that 4 mm makes for a stronger tip. At least in the case of FFG, with the distal taper, I'm not sure that's true. Comparing my original C95 to an FFG Manix 2, the tip is actually thinner.

[Slash]

Same reason axe is big. Mass X Velocity = Force. Plus, thicker = stronger.

[gaj999]

I've got a FB about the same size with a 2mm carbon steel blade. It cuts like a dream. I love the Centofantes. 2mm again. I'm kinda disappointed that the XL isn't 2mm.

Gordon

[MIL-DOT]

Same reason axe is big. Mass X Velocity = Force. Plus, thicker = stronger.

The OP seems to understand that,but I believe he's wondering if the difference in mass/weight between the 3 and 4 mm. blades would be a significant factor in something smaller like a hand-held knife. I would think the 3mm. would be more than sufficient, since a folder shouldn't be exposed to stresses like batoning or prying.

[mikerestivo]

Hi Tom -

I'm with you - I am wondering if it matters in the real world of use. I don't think it will matter. Maybe that 1mm is significant for brain surgeons and rocket scientists. I have a hard time imagining a wave of blade failures due to the XL being 1mm thinner.

Mike

[dbcad]

Blade thickness becomes a huge issue when you're looking to slice deep. 4 mm is great for tough and strong. With a FFG blade a lot will depend on how broad the blade is.

I very much enjoy the slicing capability of the 2 mm L'bug and Dyad PE. In a very tough circumstance I would think a 4 mm thick blade would be an advantage :) ( I have a Superleaf on the way )

[Rockcrawler]

I would imagine that extra less mm would help keep production cost down. Wasn't part of the Manix 2 an attempt to sell the knife for less in hopes of re-coping on higher selling numbers?

[DeathBySnooSnoo]

I would think that it would depend on your planned use. If you are going to edc it, or just never use it very hard, 3mm is fine. However I would think that those people planning on using it as a camp knife or situations where it might take more "abuse" than average, the 4mm would be beneficial.

Now I love the original and never have I felt that it was too big or heavy or any of that, and I really would have much much preferred seeing this one in 4mm, however, my use isn't going to require a hard use blade and so I am ok with it being only 3mm.
I am sure that the reason that it is not a 4mm, is that in order to add that extra thickness to the Manix 2 platform, it would have required a complete reworking of the lock. And that would have been expensive I am sure.

Maybe we can get a sprint in 4mm :D

[bh49]

I agree with everybody above that 3mm thick blade with the same geometry will be better slicer that 4 mm. But I really never thought about C95 Manix as a slicer. Cento is a slicer, Caly is a slicer. Manix is something totally different, unless you need to slice a small to medium tree. 4mm stock works pretty good on mily, and IMHO would work good on C95 as well.

[SQSAR]

I like stout knives, but there's a lot to be said for trying to keep the weight down. Sure you can skeletonize liners and such, but I've found one of the best ways to mitigate excessive weight is by going to a thinner blade stock. Of course there's a point to which you are sacrificing strength, but going from 4mm to 3mm isn't going to result in a blade that is inappropriately weak for a folder. Like Mil-Dot suggested , ,it's a folder and no one needs to be routinely batoning things with it.

I used to use 3/16 as my go-to steel when I made a field knife. I've since come to realize that for extended hikes in the Rocky Mountains, the excessive weight doesn't really help me and I've found that by going to slightly thinner blade stock I can still have a very rugged and serviceable knife, and still shave some weight, without having to make it so short that its defensive capabilities (read length) are cut too much.

[wrdwrght]

No use to which I put my 4mm Superleaf, my 3.5mm Para2, or my 3mm Manix2s (all with nearly a 3 1/2 inch blade) will reveal a meaningful difference in durability and performance, IMHO.

I would expect a significant difference in performance between my Superleaf and my Chaparral. As to durability, I would expect no difference between the two. I take it as given that Spyderco warrants the durability of whatever folder it offers, provided that folder's design parameters are not exceeded.

I simply like the aesthetic that can be found in blade stock with different thickness-to-length ratios. I love the Superleaf's proportions. Heck, I love the fact that the 2 inch blade in my Squeak is 3mm thick.

It is worth noting that Sal, in regard to thumb ramps, has said that sometimes you want a hump (Caly series), sometimes you don't (Native series). By the same token, sometimes you want a stout and hefty knife (original Manix or Gayle Bradley, for example), sometimes you don't (Chaparral or Dragonfly, for example).

Although I have expressed a wish for a Manix2 XL sprint in 4mm, if I could have just one Spydie (perish the thought!), it would be the 3in:3mm Sage2 that is normally in my pocket.

[Evil D]

The answer is pivot strength. You guys are only thinking in terms of slicing. Thicker blades offer more meat right at the pivot, which is going to make lateral and twisting strength greater than a thinner blade. Not to mention, depending on the lock design, a thicker blade can also mean a stronger lock.

[HotSoup]

Today I learned the Military has a 4mm blade. Holy crap. I was under the impression it was only 3 :O

4mm is the way to go :D

[mikerestivo]

The answer is pivot strength. You guys are only thinking in terms of slicing. Thicker blades offer more meat right at the pivot, which is going to make lateral and twisting strength greater than a thinner blade. Not to mention, depending on the lock design, a thicker blade can also mean a stronger lock.

I hear you and agree with the theory, but for most all rational usage of either 3mm or 4mm, is it going to make a difference? I would bet that the threshold in point-of-failure for a 3mm and a 4mm blade would still involve a poopload more force than would ever be put on the knife. And be honest, how are you going to use it? If you are using it to pry cinder blocks out of a wall, then I could see cause for worry.

[Blerv]

I personally think the average 4mm+ FFG offers piss poor slicing performance. Sure it may do decent for some tasks, like watermelon or cardboard but compared to a 4mm HG slicing to mid-spine there is no competition. If they want the same theory of bulletproof-ness something in the Vox 7mm range would be better.

The same logic of the general population pushed the Chinook3 into a FFG format while the 2 blew it away. While I think the Military makes sense at 4mm due to overal blade narrowness with an acute tip, the Manix XL would be overkill (and heavier/wider/more expensive).

I don't know. To each his/her own. I have yet to snap a tip let alone a blade at mid-length. I do disagree with Evil D (sorry bro) the limitation of a folder is the pivot and bushings not the 3mm/4mm comparo...folders aren't meant to twist, period. Not compared to a FB at least.

[kgriggs8]

Thinner is better for almost all use. If you are the kind of person who puts on a hockey mask, Kevlar gloves and beats on your knife with a hammer then 4mm would still not be thick enough.

[Slash]

Forgot 4mm = larger wound inflicted.

[The Deacon]

I'm in 100% agreement with Blerv regarding the relative slicing ability of 4mm blades. Am sure others think differently, but thinner is definitely better for my purposes. After cutting what seemed like a mile of thick cardboard with my Chaparral, I wish more than ever that Spyderco would make more midlocks with 2mm blades. A Stretch with such a blade would be outstanding.

[hunterseeker5]

Remember blade strength is determined by grind, depth, AND width. A FFG blade will taper toward the tip anyway, so your thickness may not be strictly relevant to cutting capability.

*edit*

What I mean by that is in essence in agreement with Deacon and Blerv which is that cutting capability will be determined by maximum thickness and thickness behind the edge bevel (depending on what you're cutting) so something like the Dragonfly2 will slice much better than a para2. In all seriousness if you want to know what "little big knife" really means buy a ZDP dragonfly, re-profile it to 20 degrees inclusive, and put a polish on it ending in .5 micron diamonds in leather (or less). It may just redefine what you feel sharp and cutting capability is.

I guess while I'm editing this I'll address the OP: these tools aren't for prying, don't worry about it. For a variety of reasons I love the thicker stock and design of the para2, but I wouldn't dismiss the Manix line for their thinner blade stock. It is its own thing, just enjoy it.

[Blerv]

Another factor of thick FFG knives is the edge angle increases quicker after multiple sharpenings (compared to thin stock or HG). This means the 4mm will take more time to sharpen and do a worse job unless you drastically rebevel or regrind it.

Of course, this is a very long-term situation. As Paul and Hunter mentioned thin blades are scary good for most tasks and 3mm seems a fair compromise. After reading about Clovisc putting the Rock Salt through its paces on trees of the Alaskan rainforest (also 3mm) I think the M2 XL will be a terrific performer.