how abusive is it really to cut metal with a knife

[Cliff Stamp]

Consider a blade used to cut the following wires :

two #6's
one #8
four fabric-coverd #14's
ten to twelve fabric covered #16's
four "after-market" plastic-coated #16's.

with a piece of sheet metal (400 series) used as the cutting board.

After the cutting the damage (require mag to see) was restored with 13 passes per side on a ceramic stone finer than the UF Spyderco stone.

The edge on the blade was ground at 15 degrees per side, and 0.009" thick at 1/16" back from the edge. It is O1 at 63.5 HRC.

Ref :

http://www.panix.com/~alvinj/ggrampa3.jpg

This isn't me, the maker did it.

http://groups.google.ca/group/rec.knives/msg/9efe817dea240594?hl=en&

the funniest part is the comment "... it only gets to 63.5 HRC".

-Cliff

 

[ghost squire]

Well it was almost 64 RC, and I don't think the scale is even linear, so thats hard as hell to put it in scientific terms. I would like to see a knife made of 440 do that.

 

[Cobalt]

Hey, maybe that is where hard chroming a blade would come in handy. After all Hardchrome is Rc of 71-75. you still have that Tusk or part of it?

 

[Cliff Stamp]

Yeah, there are not a lot of people who would consider 63.5 HRC to be soft. I think it is interesting, how many people would use a high end custom multi-blade like that.

Buck made blades which had one side of the edge hard coated. They claimed really high performance, they never caught on though and are rarely mentioned on the forums.

I think I have some of the pieces of the origional TUSK which took the huge end blow outs somewhere. I should get Tai Goo or someone to forge all the bits I have into one knife, call it the Frankenstein.

-Cliff

 

[Thomas Linton]

I think I have some of the pieces of the origional TUSK which took the huge end blow outs somewhere. I should get Tai Goo or someone to forge all the bits I have into one knife, call it the Frankenstein.

-Cliff

Oh my -- The Sword That Was Broken. (Do I hear the pitter-patter of hairy little feet?)


Speaking of Buck, didn't they used to advertise that their knives could be driven through mild steel bolts? They might have even used a trademark of a knife cutting a bolt. Or am I having a Senior Moment?

 

[Dave Rishar]

I suppose it depends on the knife, Cliff.

I have a knife that the seller (not the manufacturer, to the best of my knowledge) is very vocal about not abusing. Don't chop, don't twist, don't even steel it. I try not to. It works extremely well when it's not being misused: product as advertised.

I have another knife where the manufacturer says, "If you can break this, we'll send you two more for free." I've chopped up steel trashcans with it. This caused a few dings but it wasn't anything that couldn't be removed with a file, let alone a belt sander. Anything less didn't really do anything at all to it: product as advertised.

I have yet another knife that had some foolery on the back of the package, talking about how well engineered the knife was, why it was so expensive (it was made of 154 CM), and why I would be so pleased with it. The tip broke off constantly. It was difficult to put a lousy edge on it and it held that lousy edge for a long time. The Torx screws loosened...good luck finding a Torx driver of any size (let alone the right size, and there were two or three different sized screw) on a ship in the middle of the Pacific. I wound up keeping the thing together with lockwire. Despite being "stainless," it rusted unless oiled twice daily. The pivot loosened. The clip broke. It was a nightmare: product was not as advertised.

I have one final knife that sawed through a tire (belt and all), chopped wood, opened cans of soup and cut wire and pried open ammunition crates on a nearly daily basis for over a year before the lock developed a bit of play and it was retired to the tacklebox. The distributor would probably classify this as intentional misuse, and if I pried with the edge it would get dinged (which was exceedingly easy to hone out afterwards), but what the heck: we'll call this one product as advertised, even if it wasn't advertised as such.

If the manufacturer is saying that it's OK to cut metal then by all means, cut metal. If they warn that it's not a good idea then it's probably not - there are other tools meant to do that job.

Were you to hand me Alvin's knife and explain to me how it was made I would classify this as abusive, if that's what you're asking. Apparently I would be wrong.

 

[dsvirsky]

Speaking of Buck, didn't they used to advertise that their knives could be driven through mild steel bolts? They might have even used a trademark of a knife cutting a bolt. Or am I having a Senior Moment?

Not a Senior Moment. Buck did indeed use a knife cutting a bolt as their logo -- I still have a two blade trapper I bought about 35 years ago that has that logo on the shield.

 

[Dog of War]

Because of my brother's career designing industrial cutting tools, punches, etc. and making knives in his spare time, cutting metals has always fascinated me. IMO soft steel and copper wire can be very useful for testing the heat treat and toughness of a blade.

Cutting into wire at an acute angle, like when stripping insulted wire, can put a great deal of lateral stress on the very edge of a blade and reveal flaws - soft blades with too acute edges will roll, brittle steels chip. If reprofiling a knife for heavy use, I often run a series of tests stripping insulated strands from Romex cable, then steel wire at the same kind of angle as if stripping. This helps me adjust the edge bevel as needed, sometimes nothing more than making the secondary bevel more obtuse.

The lateral stress induced seems to be the important factor. I've seen blades with edges that didn't hold up so well stripping copper electric wire that would nonetheless cut through 1/4-1/2" mild steel bolts and similar.... the trick seems to be not blowing out the edge at the start by carefully delivering force from the hammer straight down and perpendicular to the metal being cut. Once the cut is started I think the 'V' that's been cut into the steel acts to guide and support the blade, and has a lot to do with minimizing damage to the blade.

 

[Cliff Stamp]

Speaking of Buck, didn't they used to advertise that their knives could be driven through mild steel bolts?

It was done, I am not sure exactly how it was used in the promotion.

The lateral stress induced seems to be the important factor.

Yes, all these metals are really soft, much softer than the knife edge. However they don't need to be stronger than the knife, they just need to be stronger than the edge which they can be if the relative thickness is high enough, just like you can easily break off the point of many knives by prying in wood.

Once the cut is started I think the 'V' that's been cut into the steel acts to guide and support the blade, and has a lot to do with minimizing damage to the blade.

Yes, just don't hit it on an angle or othewrise load the blade sideways as the edge will take a huge snap load. You see similar problems in batoning heavy wood with knots.

... if that's what you're asking.

I was making a point concerning baselines, consider the nature of this knife, steel and geometry, compared to knives who would rank such cutting as abusive.

When making comments about abuse you have to look beyond the specific knife in question, because abuse like all elements of performance is relative. How do other knives perform?

If something is described as abusive to one knife, but someone else can make a knife that can do it, with less steel, which cuts better for longer, has higher ease of sharpening, etc., there is a problem.

The statement of abuse has now turned into one of inferiority.

-Cliff