S30v that bends?

[HellHound]

http://www.youtube.com/watch?v=Cnao7cGM ... AAAAAAABAA
Just watched the new vid by CajunBlaze , his brother apparently tried praying smth open and bent the tip on his para2. So now I'm wondering what kind of heat treat is on there, whats the hrc? and shouldn't s30v be brittle as glass and snap instead of bend?

[unit]

I have often speculated that (especially with S30V) thinner blades hold an advantage in that they offer feedback to the slightly abusive user.

Allow me to elaborate on this speculation.

A thin blade will flex and even bend and the user can see this and gauge that damage will ensue if the activity is continued.

A thicker blade by comparison will offer very little feedback, but it will require much more force to deform or break...but the problem is, there is little warning prior to rupture.

I envision this to be due to the thickness and the stress differentials in the blade. A thin blade will have similar stresses throughout the thickness of the blade, so it flexes and generally returns to shape, but occasionally can bend. A thicker blade will have a greater stress differential throughout the blade (consider the stresses on opposing sides of the blade during prying...one side is in compression and the other in tension). If the blade is sufficiently thick it will tend to tear apart on the tension side before much flexing occurs...thus we say it ruptured like glass with very little feedback prior to destruction.

At least that is what I speculate.

So if you want to pry like crazy, a thicker tip is better, but some day it may snap on you anyway...because we all know that any tool can be broken, they just have different limits and failure modes

[phillipsted]

That's why I have several $15-$20 pry bars in my shop and in my car with me.

TedP

[unit]

That's why I have several $15-$20 pry bars in my shop and in my car with me.

TedP

For those that must pry (and carry) I recommend the mini pry bars (Widgy bar) that are small enough to fit anywhere your folder will, they take a SERIOUS amount of abuse, and cost 3-5 bucks each (in case you manage to break one). Really tough to beat that value.

[chuck_roxas45]

[Slash]

Not knocking the blaze' bro. But, a real construction worker with any sense would have an array of tools in their bags and not use a folder for cutting crap like drywall.

[Sht]

Not knocking the blaze' bro. But, a real construction worker with any sense would have an array of tools in their bags and not use a folder for cutting crap like drywall.

Can you tell me a better way to cut drywall in tactical fashion? I thought not.

[sal]

Hi Hellhound,

Without measuring your blade, I would guess Rc 59/60 which is where we run our S30V. An optimal hardness accordingto Crucible.

Hi Sht,

Welcome to the Spyderco forum.

sal

[Rwb1500]

Can you tell me a better way to cut drywall in tactical fashion? I thought not.

Schempp Rock.. :D

[nakahoshi]

Not knocking the blaze' bro. But, a real construction worker with any sense would have an array of tools in their bags and not use a folder for cutting crap like drywall.

I am in the "Construction Business" and I would NEVER cut drywall with my edc knife, ever. Its the wrong tool for the job. Period.

(Unless I had to rescue a kitten that was stuck in the wall that is.)

I once saw a co-worker burn the serrations off of a Sog Flash 2 trying to use it as a drywall saw.

Its the difference between being a Mechanic, or being Macgyver :p

-Bobby

[VashHash]

I bent my para 1 prying a bullet from a 2x4 it still cuts pretty good. I was surprised it didn't snap. I didn't realize it bent until the next day when I went to sharpen it.

[unit]

Its the difference between being a Mechanic, or being Macgyver :p

-Bobby

MacGyver would never be so lucky as to find himself with the use of a nice knife...that guy would either knap one from an old beer bottle, or forge a blade from the rusted muffler on a Chevy in a fire of burning magnesium shavings from the wheels (off the same Chevy) :D

Mechanics (the good ones) will use the right tool for the job (and pay obscene prices for those tools over then next 30 years in installments) :D

[Evil D]

MacGyver would never be so lucky as to find himself with the use of a nice knife...that guy would either knap one from an old beer bottle, or forge a blade from the rusted muffler on a Chevy in a fire of burning magnesium shavings from the wheels (off the same Chevy) :D

Mechanics (the good ones) will use the right tool for the job (and pay obscene prices for those tools over then next 30 years in installments) :D

Man you said it. I work on cars to earn money to pay for the tools i work on cars with. It's a vicious cycle

[HellHound]

Thanks guys, great answers and great suggestions. Thats what I like about this forum, you get a whole lot more helpful info then you initially asked for :)

[dsmegst]

I admit that I made a complete mess of a knife while trying to modify it. The thing ended up with a loose lock and was rendered unsafe. It also came with a FFG S30v blade and since I was about to throw it out, I put the blade in a vice and bent it about 60 degrees before it snapped in half. I was pretty impressed with how long it lasted. I expected it to give out around 30 degrees or so.

It gave me more confidence about how tough S30v blades can be.

[JCP1969]

prying with a knife is a foreseeable mistake. It reminds me of when ever I see myself getting hurt prior to doing something. I don't do it. Most of the time. My foresight is about 100% accurate. My hindsight to my foresight reminds me I'm an idiot sometimes. They say insanity is doing the same thing over and over and expecting different results .

[Ankerson]

http://www.youtube.com/watch?v=Cnao7cGM ... AAAAAAABAA
Just watched the new vid by CajunBlaze , his brother apparently tried praying smth open and bent the tip on his para2. So now I'm wondering what kind of heat treat is on there, whats the hrc? and shouldn't s30v be brittle as glass and snap instead of bend?

No, if it was that brittle the edge would just fall apart.

S30V is a tough steel.

[Cliff Stamp]

and shouldn't s30v be brittle as glass and snap instead of bend?

Not in a thin cross section.

At least that is what I speculate.

At a given arc, the internal strain will be proportional to the thickness for the exact reasons you noted. The radius of the arc and the corresponding length difference on the inside / outside curve from the center line of the knife is what causes the problem.

I am in the "Construction Business" and I would NEVER cut drywall with my edc knife, ever. Its the wrong tool for the job. Period.

I run two construction businesses, I have cut drywall on many occasions with a folding knife, usually doing inspections / trouble shooting. It is essentially just chalk, a little abrasive but nothing to be concerned about. This morning I did an inspection on water penetration and used my Paramilitary to cut open some poly, slice through some batt insulation, scrape away some concrete from a window nailing flange and probe the wood for moisture penetration and check the concrete for consistency by lighting using the knife like an ice pick into the material to check for flaking/spalling. Yes it will dent the tip, wear the blade a little and put a couple of small chips in the edge, but none of this is serious on a working tool. On another inspection I could just as easily take the same knife, cut back some sod, dig/pry in soil to expose weeping tile etc. .

Most construction workers locally will use Olfa knives for all cutting work, including drywall as you don't actually cut the plaster part, just score it and crack the board. The actual cut outs are done with the equivalent of a router, no one uses the traditional hand saws any more for window/door trims as they are too slow, which is a bit of a problem as the electric saws run so fast they will tend not to produce as clean a cut and will damage the poly and usually give the trimmers fits as they have to clean up after them when putting in the door boxes. But again it isn't something I would be concerned about, I have given my carry knives to people on site more than once or used my knives to trim drywall back from a sloppy cut when I was doing an inspection.

My brother currently is one of our main carpenters/trouble shooters and he carries a number of decent folding knives with him, usually Spyderco folders. I repair them fairly frequently when the damage is a bit severe, but aside from the occasional broken serration and snapped tip, it isn't usually significant and it still takes years to put significant visible wear into a blade. Plus the actual tools he uses do have to be replaced/repaired as well. Hammer get broken claws, chisels get torn up retrofitting windows, etc. . It isn't like they are going to baby a folding knife when they are using everything else as a tool. It is just a knife, to be used, repaired and replaced when necessary.

No, if it was that brittle the edge would just fall apart.

Not unless you were chopping with it. The edge of a knife is so thin that the plastic region is significant even on steels which have no visible ductility through the main body. Even 1095 at 67-68 HRC will deform readily at the edge as it is only 0.5 microns thick, but if you try to put a set in a blade itself it will crack without almost any flex as it has almost no plastic region at all.

S30V is a tough steel.

Jim, if you are calling S30V tough then you are using a different definition of the word than the materials definition. The toughness of S30V is so low that you can not even measure the toughness the way you do actual tough steels. The measured value for the impact toughness would be so small that it would beyond the ability of the equipment to detect it, i.e, it would just read zero. Consider if S30V is tough then what would you call 440A, then AEB-L, then 12C27M, then 420J2 then A8, then S1, then 4340, etc. . This is an increasing list of toughness in blade steels, by the time you get to the end of it the toughness is multiple orders of magnitude over S30V.

[D1omedes]

Cliff, thank you for not charging me to read your posts. I get as much knowledge from them as I did any one of my college courses. :)

You seem to know an awful lot about steel and knife making for a contractor. Do you make your own knives on the side?

[Ankerson]

Not in a thin cross section.



At a given arc, the internal strain will be proportional to the thickness for the exact reasons you noted. The radius of the arc and the corresponding length difference on the inside / outside curve from the center line of the knife is what causes the problem.



I run two construction businesses, I have cut drywall on many occasions with a folding knife, usually doing inspections / trouble shooting. It is essentially just chalk, a little abrasive but nothing to be concerned about. This morning I did an inspection on water penetration and used my Paramilitary to cut open some poly, slice through some batt insulation, scrape away some concrete from a window nailing flange and probe the wood for moisture penetration and check the concrete for consistency by lighting using the knife like an ice pick into the material to check for flaking/spalling. Yes it will dent the tip, wear the blade a little and put a couple of small chips in the edge, but none of this is serious on a working tool. On another inspection I could just as easily take the same knife, cut back some sod, dig/pry in soil to expose weeping tile etc. .

Most construction workers locally will use Olfa knives for all cutting work, including drywall as you don't actually cut the plaster part, just score it and crack the board. The actual cut outs are done with the equivalent of a router, no one uses the traditional hand saws any more for window/door trims as they are too slow, which is a bit of a problem as the electric saws run so fast they will tend not to produce as clean a cut and will damage the poly and usually give the trimmers fits as they have to clean up after them when putting in the door boxes. But again it isn't something I would be concerned about, I have given my carry knives to people on site more than once or used my knives to trim drywall back from a sloppy cut when I was doing an inspection.

My brother currently is one of our main carpenters/trouble shooters and he carries a number of decent folding knives with him, usually Spyderco folders. I repair them fairly frequently when the damage is a bit severe, but aside from the occasional broken serration and snapped tip, it isn't usually significant and it still takes years to put significant visible wear into a blade. Plus the actual tools he uses do have to be replaced/repaired as well. Hammer get broken claws, chisels get torn up retrofitting windows, etc. . It isn't like they are going to baby a folding knife when they are using everything else as a tool. It is just a knife, to be used, repaired and replaced when necessary.



Not unless you were chopping with it. The edge of a knife is so thin that the plastic region is significant even on steels which have no visible ductility through the main body. Even 1095 at 67-68 HRC will deform readily at the edge as it is only 0.5 microns thick, but if you try to put a set in a blade itself it will crack without almost any flex as it has almost no plastic region at all.



Jim, if you are calling S30V tough then you are using a different definition of the word than the materials definition. The toughness of S30V is so low that you can not even measure the toughness the way you do actual tough steels. The measured value for the impact toughness would be so small that it would beyond the ability of the equipment to detect it, i.e, it would just read zero. Consider if S30V is tough then what would you call 440A, then AEB-L, then 12C27M, then 420J2 then A8, then S1, then 4340, etc. . This is an increasing list of toughness in blade steels, by the time you get to the end of it the toughness is multiple orders of magnitude over S30V.

You have to remember as the hardness increases the toughness drops so something like 3V being as tough as it is at 56 RC won't be nearly the same at 61 HRC. Hardness and the tempering process has to be matched with the steel and the intended use of the blade.

Same with S30V, drop the hardness down from 60 RC to around 56 and it does get a lot better.

Unless one is making choppers out of them it really doesn't really matter anyway...... That is unless one wants to hit them with a hammer pounding them through steel and rocks. Hardly even extreme use for the typical EDC type folder unless they are trying to break the knife on purpose.