materials affecting edge retention

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BITEME

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hello guys I have a question ? I use several knives at work vg-10,s30v,aus8,ats-34 and I've been cutting elect. tape,nylon rope ,small poly tubing and It seems like my blades dont stay sharp too long ,I get them hair popping sharp but after awhile a couple days or so they are not shaving sharp and truthfully I expected more from them,help
 
Try sharpening them at a steeper angle if you think the dulling is from a rolled edge. Unless your folders are at Rc60 or above, you may continue to be disappointed.

If you are truly abrading away the edge with coarse/abrasive materials, then you need to step up to a high vanadium content steel. The S30V is pretty high, but depending on how hard the maker heat treats the blade, your results will vary. S90V has a bunch of hard vanadium carbides, and is a step up from what you are using.

If chipping of edge is happening (look at under magnifying glass), step up to a hard blade of CPM 3V or CPM M4, both of which can be run hard and still be tough.
 
This is my first post on the forum and I'm by no means an expert. Could it be you're creating a feather edge that just won't hold up? Another possibility is adhesives from the tape you're cutting. Could you be gunking up the edges?

Joe
 
Cutting anything will gradually degrade a 'shaving sharp' edge, no matter the steel. Some things more than others (such as the nylon rope, especially if it's dirty). Depending on the makeup of the 'poly tubing', that might dull the edge too (some types are very cut/abrasion-resistant).

That being said, it's possible & fairly common that a burr or wire edge might be the issue. After sharpening on a stone, sandpaper, etc., usually there will be at least a bit of a burr or 'wire edge' left. It's basically a very thin, fragile sliver of weakened steel at the very edge. It's possible that it'll cut OK for a short while, then it'll fold over to one side or the other. Then the edge becomes noticeably duller. Stropping the blade (using edge-trailing strokes) on leather, hard felt or other similar material should help to break off the burr or wire edge. Once that's done, edge retention will almost always be significantly better.
 
awesome ,Joe thats what I've been wondering myself ,if that were true do you think that some type of cleaner gas,lighter fluid ,or something of that nature would clean it up enough so that it would be shaving sharp again without resharpening?
 
Why does it need to be "shaving sharp?" My knives that I use for general utility (which is what I would call your use) only get sharpened down to about a 600 to 800 grit diamond stone (I don't put a fine edge on it). This technique leaves a sort of "micro-serration" on the edge, and it seems to hold up better to general utility work.

Just a thought -- might be worth a try.
 
I keep a couple of knives sharpened at 15° to impress folks with how sharp they are.

However, my knives for general work get sharpened at 20° per side with about 600 grit. They aren't "hair-popping" sharp, but they keep on cutting for a very long time.
 
All knives dull, its a fact of life that a knife is not gonna stay sharp, especially at the 100-95% level (as in 95% of full sharpness or shaving sharp). Even the best steels have been shown (someone else's tests, not mine) to degrade to like 80% of the original sharpness at rate not much better than decent/mediocre steels. After that however is where the super steels show their stuff and keep that 80% edge for a long time.

My solution to this is simply early maintenance with a strop, just strop your blades a couple of times at the end of the day and you'll be able to keep that shaving sharp edge for a much longer time.
 
I would imagine the poly tubing could be pretty tough on your blades, as well as the nylon rope.

As said above it could depend on the heat treat of the blades you are using. Are these less expensive knives? If so the heat treat could be sub par. S30V is one of the better steels for edge retention, but if its not hardened properly it can work like a completely different steel.
 
cutting cardboard & tape leaves a residue on the blade that simply causes lots of drag. supersharp blades in most cases lose this keenness quickly simply due to the mechanics involved in reducing bevels to such acute angles. as knarfeng mentioned a more sturdy bevel will keep working longer. a little blade cleaning several times a day & a palm strop will do wonders to increase edge endurance.
dennis
 
I'll try not to be so finnicky about the "shaving sharp" guideline and I'll see how that works out.My knives are usu. BM,Spydercos,Kershaw,etc so I think the heat treat should be sufficient but then again?? also what is a palm strop? I have some idea I guess but do you guys have any pics of a palm strop?-thanks again
 
Javelin said:
All knives dull, its a fact of life that a knife is not gonna stay sharp, especially at the 100-95% level (as in 95% of full sharpness or shaving sharp). Even the best steels have been shown (someone else's tests, not mine) to degrade to like 80% of the original sharpness at rate not much better than decent/mediocre steels. After that however is where the super steels show their stuff and keep that 80% edge for a long time.

My solution to this is simply early maintenance with a strop, just strop your blades a couple of times at the end of the day and you'll be able to keep that shaving sharp edge for a much longer time.
Click to expand...

+1 on this. I had the same experiences as the OP as I experimented with premium blade steels over the years. They all seemed to lose their extreme sharpness fairly quickly but did stay very sharp for a very long time.

I invested in a nice benchtop strop and some chromium oxide paste (from HandAmerican). The premium blades will come right back to scary sharp with a few swipes on the loaded strop and don't need "real" sharpening very often.

Stay sharp,
desmobob
 
I've had horrible trouble cutting any kind of tape. The glue picks up any dirt/debris and sticks it to the edge and the glue itself masks the edge and covers over it. Try a good cleaning w/ some solvent.
 
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