Tenacious edge retention

[Chrottos]

Hey, guys! I got my Meadowlark 2 in a couple months ago and it's been working great. As many of you know, the Byrd line is manufactured overseas and uses the softer 8Cr13MoV steel. The only problem I have with the Meadowlark is edge retention when being hair-whittling sharp. After cutting just a couple strips of cardboard, the sharpness would suddenly be sub-shaving. I recently fondled a Tenacious in a knife shop and have been in love ever since, especially due to the sweet price.

Is the 8Cr13MoV of the Tenacious of any higher quality than the Byrd line? Does the dulling have anything to do with microbeveling (I'm microbeveling the default edge to 40 degrees inclusive)?

In advance, thanks for your help.

Regards,

Chrottos

[sal]

Hi Chrottos,

Welcome to our forum.

We use the same steel in the byrd line and the Tenacious family. Edge retention will be about the same. If good edge retention for wood is the goal, I would try to steer you to a higher carbide content steel. Many here can recommend some.

sal

[Cliff Stamp]

HAs many of you know, the Byrd line is manufactured overseas and uses the softer 8Cr13MoV steel. The only problem I have with the Meadowlark is edge retention when being hair-whittling sharp. After cutting just a couple strips of cardboard, the sharpness would suddenly be sub-shaving.

That isn't the steel, the edge either has a burr, or was not destressed before sharpening, or is stressed during sharpening.

[Chrottos]

Could you elaborate? What do you mean by destressing/stressing the edge? I use the fine sharpmaker rods and a leather strop. What can I do to prevent this issue and increase edge retention?

[razorsharp]

Try stropping on your jeans, stick a wooden board in our jeans leggings and use them as a strop. strop with fairly high pressure, about 10 per side.Check the edge with a flashlight, if you see a wire of light at the edge, strop some more. you dont want that bright wire on the edge. Go back to your sharpener and with some feather strokes, sharpen about 5/side. Strop it with only moderate pressure on the denim, this might leave a stronger edge.

EDIT: i see you have a leather strop, that works too

[Chrottos]

Thank you for your very quick reply! I am a big fan of Spyderco and honored to recieve advice from you. Let's hope I get my hands on a Spyderco when Christmas comes around :)

Chrottos

[jackknifeh]

Hey Chrottos

Cardboard varies depending on what goes into it. I'm no expert but this is my understanding. Some of it will damage knife edges, especially razor sharp edges almost immediately. I have heard (read) where some people who cut a lot of cardboard during the day don't sharpen their knives to the point they are razor sharp. The sharp, but not razor sharp edge may perform better in the long run. Here is an exagerated example. If you cut a steak on a hard ceramic plate with a razor sharp edge the portion of the edge that contacts the plade will roll and not cut anything after just one cut. But, if you "take some edge off" by using one or two very light strokes on a fine grit ceramic stone or rod you will take some razor sharp edge off and the knife will continue to be an excellent steak knife. I'm thinking the same thing may help when using 8Cr13MoV. A rounded off edge (microscopic level) may stay sharp longer than the fragile razor edge. There are probably people here who can confirm this theory or say that I am wrong.

The better choice of course would be to get a knife with a more appropriate steel. The few steels I've used that Spyderco uses are VG-10, S30V, M4, ZDP-189. All of these will hold the edge better than 8C... There are several Spydercos that use S30V (and VG-10) and I really like it for performance as well as cost effectiveness within the better steel choices. I have cut up quite a few pizza boxes with almost no loss of edge for what I call a lot of cutting. I also do a lot of whittling on sticks from my trees. I don't think wood like that, though harder, isn't as hard on an edge as cardboard.

[Cliff Stamp]

Could you elaborate? What do you mean by destressing/stressing the edge?

The edge after use when blunted is heavily stressed, deformed, cracked, etc. though on a micro-level. If the knife is sharpened without removing this damaged steel it will collapse again very quickly just like when you fold a piece of paper it folds again along that same line very easily.

To destress the edge make a very light cut into the brown rods before you start to sharpen as if you were trying to saw the rod in half. But use very light force, not even the weight of the knife, just 10 grams or so. You are just trying to grind off the weakened metal, if you press hard you will take off too much, this doesn't harm the knife but does make sharpening more work than necessary.

I use the fine sharpmaker rods and a leather strop. What can I do to prevent this issue and increase edge retention?

Stop using the strop, the most likely reason for the edge blunting very quickly is that the stropping is stressing it by mechanically deforming the edge back and forth. The edge should be clean and sharp right off the stones.

[Blerv]

A good sharpening goes a long way. Still, hair-splitting edges aren't going to last long with cardboard cutting. Staying sharp though should be a reasonable expectation.

[chuck_roxas45]

A good sharpening goes a long way. Still, hair-splitting edges aren't going to last long with cardboard cutting. Staying sharp though should be a reasonable expectation.

This^^.

[razorsharp]

The edge after use when blunted is heavily stressed, deformed, cracked, etc. though on a micro-level. If the knife is sharpened without removing this damaged steel it will collapse again very quickly just like when you fold a piece of paper it folds again along that same line very easily.

To destress the edge make a very light cut into the brown rods before you start to sharpen as if you were trying to saw the rod in half. But use very light force, not even the weight of the knife, just 10 grams or so. You are just trying to grind off the weakened metal, if you press hard you will take off too much, this doesn't harm the knife but does make sharpening more work than necessary.



Stop using the strop, the most likely reason for the edge blunting very quickly is that the stropping is stressing it by mechanically deforming the edge back and forth. The edge should be clean and sharp right off the stones.

if you strop and break that burr of very edge off, then theres no reason not to do it, then sharpen it back to apex carfully

[kbrouwer]

I recently posted a poll about a steel upgrade to the Tenacious line. Check that post out for some info on steels and value knives. http://www.spyderco.com/forums/showthre ... Value-Line

[egbladesmith]

if you strop and break that burr of very edge off, then theres no reason not to do it, then sharpen it back to apex carfully

My assumption would be if he is here asking this advise, he might not know how to do it correctly. But yes, given the know how, either way would be acceptable.

[Chrottos]

Thanks for all the advice, guys! I'll try some new techniques and maybe get me that Tenacious for Christmas!

Chrottos

[Cliff Stamp]

if you strop and break that burr of very edge off, then theres no reason not to do it, then sharpen it back to apex carfully

There are a few concerns :

-why is the edge burring significantly, it should not (major issue)
-bending the edge back and forth stresses the steel under the break
-it is very time inefficient and adds unnecessary complexity
-it creates more work having to apex again

The first two are fairly major, the last two are fairly minor.

This edge easily cuts cardboard for an extreme length of time :

http://www.youtube.com/watch?v=5At3NtNKHFA

This edge is slightly finer, easily shaves and cuts cardboard for an extreme length of time :

http://www.youtube.com/watch?v=mSt2mCWGFII

[Cliff Stamp]

The better choice of course would be to get a knife with a more appropriate steel.

8Cr13MoV is designed for that type of work, cutting abrasive materials, hence the Carbon/Chromium ratio which puts it into the aggregate range where it will form large chromium carbides, 10-15 microns in size. If a shaving sharp edge is being lost in a few cuts then increasing to a higher carbide steel will not solve the problem, it in fact will make it worse as those steels are not designed to hold razor sharp edges.

A few cuts into cardboard is a common (though not optimal) way to remove a burr because if the edge has a significant burr the cardboard is usually dense enough to collapse/break or wear it off in 1-2 passes. That is all that is happening in this case, it is simple an issue with sharpening - assuming the steel itself isn't flawed in the HT/composition which is unlikely but a few simple checks could resolve that as well.

[Blerv]

Those are amazing vids Cliff. No intent to kiss up; I learned a lot.

[anagarika]

Cliff,

Are you saying that 8Cr is actually composed to last for a while cutting cardboard? What a relief

So if a particularly knife doesn't do well, HT or the sharpening are the most probable causes?

[razorsharp]

There are a few concerns :

-why is the edge burring significantly, it should not (major issue)
-bending the edge back and forth stresses the steel under the break
-it is very time inefficient and adds unnecessary complexity
-it creates more work having to apex again

The first two are fairly major, the last two are fairly minor.

This edge easily cuts cardboard for an extreme length of time :

http://www.youtube.com/watch?v=5At3NtNKHFA

This edge is slightly finer, easily shaves and cuts cardboard for an extreme length of time :

http://www.youtube.com/watch?v=mSt2mCWGFII

Lets say we both have a 600 grit edge, same angle- yours sharpened your way, (sharpen to a sharp edge with a light burr , high angle into the stone to remove it, then sharpened gently back to apex)- mine done on the stones till there's a light burr, Ill strop it off, then sharpen very lightly to the brink of burring,( hair whittling, from both sides of the edge with ease) then ill refine the teeth on an unloaded denim strop. (adds that extra 2% to your sharpness , takes 30 more seconds ) I'd probably start with the sharpest edge, and we would probably cut close to the amount of cardboard till were at 5%sharpness; assuming the abrasion each knife is coming up against is identical. Mine might even outcut yours, even if only by 1 cut. My edge is going to dull down to the same sharpness as yours, in a few cuts anyways .

Im starting to confuse myself as to what im getting at lol

[Chrottos]

So, it seems I'm not the only one wondering how to increase 8Cr edge retention. I apologize, I am a huge noob when it comes to sharpening, but I cant help but want to learn more. Using the stock Sharpmaker, how would I go about sharpening for optimal sharpness and retention, from start to finish? Would microbeveling to 40 still be a good idea?

Chrottos