How strong is your edge?

Diomedes Industries

Diomedes Industries

Joined
Mar 19, 2007
Messages
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If you drug the blade of your knife over a firesteel - to make sparks (for whatever reason) - would you expect your knife to be shaving sharp when done?

What about if you scraped your blade over pine or cedar to make shavings - would the edge still shave when done?

What kind of damage would either of these do to your blade? Be sure to note the steel.

TF
 
scraping a sharp edge perpendicularly over any surface will dull it to some extent...

that's why i either use a dedicated striker or the sharp spine of a blade.

but if for some inexplicable reason i was forced to use only my knife edge, i know from experience that striking a firesteel will take a small bite out of the edge of many knives, regardless of steel.

scraping wood doesn't really do that much noticeable damage to a sharp edge, so i'm not concerned about it...
 
My go-to general-purpose knife, the one I'd want most if I was lost, is a CS Master Hunter, "Carbon-V" steel, one the last ones made.

firesteel - no, the edge would dull. Touch-up-able with a few strokes on the small ceramic stone I carry with it. But why mess with it, the spine is nice and square, I use that instead.

wood - yes, no problem. I have draw-knifed with it on pine, maple, etc waiting for it to get dull and it only ever needs a strop- after a lot of scraping.

I highly recommend this knife. I haven't tried the stainless version.
 
i made a striker for a member here and when i tested it out i noticed there was some burning on the edges but nothing serious. i never tested it on the edge but i would imagine some damage. i dont have a firesteel so i cant test it on any of the knives i made but i will just to see what happens. brian jones has a chopper that i made which he has used to chop drywall with. he said the chopper still shaves so i'm curious to know how it will hold up to a firesteel. its a convex edge also. i called and left him a message to test the edge with a firesteel. i'll make a post when he gets back to me. here is brians post if you want to read it http://www.bladeforums.com/forums/showthread.php?t=609189
 
I use a dedicated striker for the firesteel. My edge does not dull from scraping wood for shavings and tinder.
 
The thinner and sharper your blade is will determine this to a great effect. A convex edge will probably be much less apt to fold over when scraping, the edge could be stood back up with a steel or stone. This is one strength of thicker blades IMO. A good cutting edge can be pretty fragile in a thin blade.

My thicker blades like my Kabars handle scraping pretty well but I would not care to se the cutting edge on a fire steel. On my LMF fire steel, the striker that comes with it works much better that any knife that I have tried with it.
 
I prefer using the blade of a knife as my firesteel striker. My compromise is to have a knife more or less dedicated to do this. In effect, my firestriker is a small knife. Perhaps the added benefit is that my striker can be called upon to do knife like things in an emergency.

In any event, I tend to use the devoted striker often enough that my thinking about the so called damage that it does to a knife edge has been much alleviated. The striker knife I use is made of 1085. It certainly isn't as grabby as a freshly sharpended knife, but it certainly wouldn't be classified as dull and unable to cut either. In fact, as a striker, the knife works a little bit better when the edge isn't so grabby.

I find that shaving wood has hardly any noticable effect on sharpness of any of my carbon knives. Cutting cardboard is the quickest method to dull an edge. Since we are knife nuts, I think we place far too much emphasis on sharpness. Just like a little bit of rust fuzz on the knife, the fact that the knife doesn't shave hair from your arms, doesn't mean it can't perform very well at most camp and knife tasks.

Now mind you a very dull knife is a dangerous and poor tool, but hardly any of us really let our knives actually get dull by those kind of standards. It seems, that the other extreme is more prevalent here especially as of late. That is people wanting to put a super shallow grind and optimize slicing capacity of their edges at the risk of weakening the edge for more robust chores. I think there is a balance that should be struck between edge geometry, robustness and sharpness weighed against knife function. The manufactures usually give us some guidance on this when setting up their designs, and often times we will change them to better suit our specific needs a bit better.

Personally, right now I like to convert my more course v-grinds to a shallower convex and then set the final edge with a micro-beveled v. It seems to work out pretty good for me and the shallower convex seems to give a good compromise to the thicker/course V-grind in affording good edge robustness while increasing slicing abilities. I have not yet rolled any of my edges during chopping.
 
I use the spine or a dedicated striker for my firesteels. I have used the edge in the past with some dulling occuring, but I would only do that in the field if I had to...
I don't care about SUPER sharpness. Shaving sharp is fun, but I'm not so concerned about it that all my knives are that way. I have mostly O1 or 1095 convex grinds with a couple of scandis thrown in and I'm personally not technically minded enough to care or worry about secondary bevels. I know when the edge grabs a bit when slicing paper that I might want to consider touching it up a bit.
 
I use a dedicated striker for ferro rods. My SRKW HRLM (52100) will hold an edge for a ridiculously long time when using it for its intending purpose (knife stuff). Scraping bark and wood to obtain tinder has little effect in the short term with this particular blade. Any steel, regardless of maker and/or treatment, will dull over time whether you are using it to cut paper or scrape bark/wood. So far this winter my HRLM has field dressed 2deer, cut down 2 saplings in order to transport said deer and performed a wide array of "knife chores" - it will still shave and push cut although I can tell it is not quite as sharp as it was before the season started. I have stropped it a few times on a dry leather belt over the last 3 months but thats about it.
 
This is totaly dependant on the edge geometry. And I think there is no reason to scrape your edge down a firesteel. Those things get to 3000 degrees, and there is no reason to subject your edge to 3000 degree sparks. Especially since the spine of the knife should work fine.

An edge should be able to tolerate some shaving for tender. It should hold up for a time. You shouldn't have to go resharpening it every hour.
 
Fiddleback said:
This is totaly dependant on the edge geometry. And I think there is no reason to scrape your edge down a firesteel. Those things get to 3000 degrees, and there is no reason to subject your edge to 3000 degree sparks. Especially since the spine of the knife should work fine.
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That's my opinion as well. I think the superheating of the edge would cause more and longer term damage than any wear. Some knives have a small notch at the base of the edge, somewhat like a spanish notch, for use with ferro rods.
 
Fiddleback said:
This is totally dependent on the edge geometry. And I think there is no reason to scrape your edge down a firesteel. Those things get to 3000 degrees, and there is no reason to subject your edge to 3000 degree sparks. Especially since the spine of the knife should work fine.
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Yet another who agrees with this statement completely!

Considering you don't even need to use a steel edge on a firesteel - a broken piece of glass or a sharp flint rock will do - why on earth would you ruin your edge? Especially since most spines are square enough to generate sparks. I'd have to be in very desperate straits before I used my knife edge on a firesteel!
 
Sorry Andy - I totally disagree with your logic. The edge of a knife, even when thinned out is a very large heat sink. While the temperature of the sparks do get hot in temperature terms, the actual quantity of kinetic energy in joules or calories is minuscule. The heat itself is generated primarily by the chemical reaction and oxidation process of the firesteel components rather than by friction. Thus the focal point of that heat is generated on the exterior of the spark rather than the scraper. Taken together that 1) a small quantity of energy, albeit high temperature is produced; 2) that the heat in the spark is generated at the spark surface more so than at the site of friction and 3) steel is a good heat conductor; the heat produced by a firesteel spark should be rapidly dissipated across the edge. I just simply can't believe that you will damage the temper of a knife by sparking a firesteel.

Now grinding a blade with a mechanical grinder or belt is a different story. You have a wide belt (0.5 - 1" diameter) generating heat at the blade surface and it the friction at both the belt and blade that contributes to the heat generation. There is a large area over which the heat energy is produced and thus the quantity of energy generated is quite large and remains relatively focused on the edge of the knife. This is why the temper is so easily destroyed by grinding in an inappropriate manner. I don't think the analogy can be extended to a firesteel spark.

There are also reasons why you might not want to use the spine of your knife. Coated blades can't produce a spark. Secondly, there is always a danger (and even I've done this before) of you forgetting about the edge during sparking and cutting yourself in the process.
 
kgd said:
Sorry Andy - I totally disagree with your logic. The edge of a knife, even when thinned out is a very large heat sink. While the temperature of the sparks do get hot in temperature terms, the actual quantity of kinetic energy in joules or calories is minuscule. The heat itself is generated primarily by the chemical reaction and oxidation process of the firesteel components rather than by friction. Thus the focal point of that heat is generated on the exterior of the spark rather than the scraper. Taken together that 1) a small quantity of energy, albeit high temperature is produced; 2) that the heat in the spark is generated at the spark surface more so than at the site of friction and 3) steel is a good heat conductor; the heat produced by a firesteel spark should be rapidly dissipated across the edge. I just simply can't believe that you will damage the temper of a knife by sparking a firesteel.

Now grinding a blade with a mechanical grinder or belt is a different story. You have a wide belt (0.5 - 1" diameter) generating heat at the blade surface and it the friction at both the belt and blade that contributes to the heat generation. There is a large area over which the heat energy is produced and thus the quantity of energy generated is quite large and remains relatively focused on the edge of the knife. This is why tempering is so easily destroyed by grinding in an inappropriate manner.

There are also reasons why you might not want to use the spine of your knife. Coated blades can't produce a spark. Secondly, there is always a danger (and even I've done this before) of you forgetting about the edge during sparking and cutting yourself in the process.
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Darn scientists, always pointing out the truth with their logic and substantial actual findings. :D
Just teasing kgd!
 
Whatever can happen will happen. I believe thats a law. Why risk your edge.

I say if you go scraping the edge of a knife down anything metal, you void the warranty.
 
I've used the edge of my RC6 for striking, it hasen't done any damage, and really didn't effect the sharpness that much. Lost a little bit of shaving ability, but it was still very much usable.

I usually dont have to use the edge, what knife I have with me has perfectly usable spine. But in worst case, I know the edge of my knives (S30V, 1095, O170-c, Carbon V, 154cm and many others) Will do fine.:thumbup:
 
Shaving wood like pine or cedar shouldn't dull a knife too quickly. I would have doubts about any blade that couldn't make a fuzz stick without significantly dulling the edge. Impact and trying to baton through knots might mess up a thin edge.

IMHO, convex edges rule for heavy use.

As to the firesteel, if I had to use my "good" knife, I would scrape using the very base of the blade.

Other options:
-Square the spine edge in one area for scraping. Moras are perfect for this.

-On an SAK, sharpen/square the screwdriver tip for firesteel striking, or notch the side of the screwdriver with a Dremel to fit your firesteel diameter. Check out the specialized firesteel scraper notch built into the Light My Fire SL3 knife:

SL3.jpg


-Of course, you could use the factory scraper or make one from a hacksaw blade and avoid the issue.

-Use a pico wedgie prybar from County Comm

-Use a p-38 can opener

-Use a Craftsman 4-way pocket screwdriver-- this is an item that is great for a all-round EDC and survival pocket tool and should be mentioned in this forum.

00904160000




-I add SAK Classics to my survival necklace/lanyards to use for firesteel scraping. I should square the edge of the nail file and save the blade.

This is all aimed at survival scenarios. If you use your firesteel a lot, I would have a dedicated scraper.
 
I have never tried it, so I am not sure how it would do. I imagine it would dull it a little. Wood shaving doesn't do much to my blades, though.
 
This has answered my question - and a very good discussion to boot.

Let me clarify. I am not talking about making a fuzz stick - I am talking about SCRAPING (perpendicular to the wood).

Thanks for the well thought out logic and arguments guys!

TF
 
Hey T - Yeah gotcha on the scraping part. Sometimes, I like to pry the bark off a piece of standing wood and then scrape sawdust with the edge of the knife to make natures kindling. Again, I don't find this really dulls a knife. If the wood is dry, then the dust will catch a spark pretty good. As long as they don't blow away. The pic below is more curls than shavings, but I do some scraping usually too!

DSC_0029-11.jpg
 
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