Sharpmaker enough for M4 or K390?

[DunninLA]

Hi, long time no post.

Years ago I had a Native 5 in 110v, an Endura4 in ZDP-189, and a Para2 in S30v. I had no luck trying to sharpen the ZDP-189, and could never get it to cut paper as would be expected of a good edge.

I sold the Native5, and lost the other two in a move. Then I bought a 130mm a Japanese Blue #2 petty knife for the the kitchen (Anryu, good knifemaker), but also whenever I needed to cut carpet up, or cardboard, or scrape what is left of labels off glass, etc. I would use the Anryu. The somehow I chipped the tip off, plus put a chink in the cutting blade. Anyway, somehow I lost it remodeling the house.

So, I want to get an EDC again. I always had my eye on the Centofante... that geometry just looked awesome and I didn't even care it's in VG10, at least I know its easy to sharpen with the Sharpmaker. So I bought one last week and it's on the way.

Now, the chipping and tip break of the Blue #2 petty tells me I'm hard on knives, so I want a steel high in toughness, like M4 or MagnaCut. But Spyderco doesn't use Magnacut and I saw a vid that said Hogue screwed up its tempering of Magnacut and they're ****. So that means I'm left with M4. Also saw a vid saying in his opinion Spiderco treated the Para2 M4 too low, but that possibly other Spidey models have better treated M4. Is that true, and if so, what model of Spyderco in M4 has the best treatment? I am thinking of Native 5

Has anyone attempted to keep a good edge (toothy, not mirror) on M4 using the Sharpmaker? Or K390? I know K390 isn't tough at all, but maybe I want one just because of how cool it is. I have a Sharpmaker from 2013 with the two regularly supplied triangle stones (medium and fine), plus also diamond, and Ultrafine. I use it to sharpen my blue #2 Santoku.

[kennethsime]

It’s absolutely doable with the Diamond rods. I used to dread sharpening my high-carbide steels on the Sharpmaker, but ever since picking up the CBN rods it’s become no big deal. I used my CBNs to reprofile my K390 PM2 the other day (and remove a couple of chips).

Have you tried Cruwear? There are some great options available in Cruwear. Also, the Magnacut Native 5 is starting to hit dealers if you really wanted to go after it! K390 is relatively tough for having such high wear resistance - much tougher than Maxamet, or S110V.

If you really want a hard use knife, you also might consider LC200N. Great tough stainless option there.

[JoviAl]

I use my knives daily for forestry/outdoor work and if I know I’m going to be battering a knife I will opt for either 3V, 1095, cruwear or Magnacut (in descending order of seeming toughness from my user experiences). I damaged my Magnacut mule blade quite badly last week and it was a chore to repair even with my diamond plates on my KME. I suppose my takeaway from this is that one knife is rarely the answer to all situations - my machetes and billhooks are built to take a beating, my mule with handle it, whereas my 4V native chief probably wouldn’t thank me for hacking brush off of trees with it.

To come back to your question, I have M4 and it is great once sharp but my gosh does it rust fast (I live in the tropics and it will begin to show rust forming in under 2 hours of pocket time, even when coated with KPL knife shield which is brilliant on everything else). I don’t have any K390 yet but am keen to pick up a police with it when they arrive here.

Have you considered a fixed blade if you are going to be hammering your knife? They really are an order of magnitude more durable than folders in my experience. The Magnacut mule is excellent (just don’t punch it edge first into steel like I did ).

[DunninLA]

thanks for your replies.

I live in Southern California, which is really a desert-ish climate, so humidity isn't an issue for M4.

I considered Cruwear, but I'm not punching holes in metal cans or trying to chip out concrete or anything weird like that, so I thought M4 will be tough enough, and it holds its edge better than Cruwear per that Nerd metalurgist guy's charts. M4 will be miles better than Japanese Blue #2 at 62 HRC. The only other one that looked interesting is Vanadis 8, but it seems very uncommon.

I wonder if Chef's Knife makers will try MagnaCut... now THAT would be interesting.

[RustyIron]

I saw a vid that said Hogue screwed up its tempering of Magnacut and they're ****. So that means I'm left with M4. Also saw a vid saying in his opinion Spiderco treated the Para2 M4 too low

Has anyone attempted to keep a good edge (toothy, not mirror) on M4 using the Sharpmaker? Or K390? I know K390 isn't tough at all

Hey, Dunn.
Don't pay too much heed to the Tik Tok Jockeys who spew about subjects where they are ignorant. I'm no metallurgist, but if I had to place my confidence in a social influencer looking for likes, or Hogue's and Spyderco's heat treating departments, it would be the latter.

I've used both M4 and K390 from Spyderco. The Sharpmaker is not my primary tool for most sharpening tasks, but I use it exclusively on a K390 Spyder Edge. I find the ceramic stones to be very good for this purpose, and they give me a satisfactory edge. The diamond stones are not my favorite. I feel they're too coarse for most of my needs. But they'll remove a lot of material quickly. If the Sharpmaker is your only sharpening tool, go ahead and get the diamond stones. But you'll want to do the finish work with the ceramic stones.

P.S.
Don't write off K390 as being "untough." I've found in my exceedingly unscientific testing that it suffers surprisingly little damage through regular day-to-day use.

[Matus]

I have k390 PM2. Using the Sharpmaker for anything else then trying to apply something like a micro-bevel the sharpening is taking forever.

I personally would really recommend to anyone who is serious about sharpening (and in particular thinning / regrinding) to get a good quality diamond stones (BBB ones are probably the best there is, but also Gesshin von JKI should be excellent. I personally use 400 and 2k from Practical Sharpening). To give anyone an idea - to sharpen k390 on good quality diamond stone is about as fast as BD1N on a conventional ceramic stone (e.g. Shapton Pro or similar). Spyderco ceramic stones thanks to their super low wear are inherently slower, though at given grit will produce a finer edge. I like the edge off the brown stone a lot.

This all does not mean that I do not like Sharpmaker, but I prefer to set a little more acute edge angle with some other sharpening tool first, and then use Sharpmaker to refresh the edge under gently larger angle - effectively adding a gentle microbevel.

I would love to see Spyderco to introduce a double-stuff sized stone with one side 400-600 grit diamond stone (stone, not plate!) and the other the brown ceramic.

[Evil D]

Anyone claiming anything about heat treat issues without hardness testing to back it up is just spouting verbal diarrhea.


Sharpmaker can handle any steel with diamond/CBN rods, it's just slower than some other sharpeners but also has the lowest learning curve.

[benben]

I keep my K390 Endela super sharp with just the brown rods, and I’m definitely no sharpening expert.

[WilliamMunny]

Hi, long time no post.

Years ago I had a Native 5 in 110v, an Endura4 in ZDP-189, and a Para2 in S30v. I had no luck trying to sharpen the ZDP-189, and could never get it to cut paper as would be expected of a good edge.

I sold the Native5, and lost the other two in a move. Then I bought a 130mm a Japanese Blue #2 petty knife for the the kitchen (Anryu, good knifemaker), but also whenever I needed to cut carpet up, or cardboard, or scrape what is left of labels off glass, etc. I would use the Anryu. The somehow I chipped the tip off, plus put a chink in the cutting blade. Anyway, somehow I lost it remodeling the house.

So, I want to get an EDC again. I always had my eye on the Centofante... that geometry just looked awesome and I didn't even care it's in VG10, at least I know its easy to sharpen with the Sharpmaker. So I bought one last week and it's on the way.

Now, the chipping and tip break of the Blue #2 petty tells me I'm hard on knives, so I want a steel high in toughness, like M4 or MagnaCut. But Spyderco doesn't use Magnacut and I saw a vid that said Hogue screwed up its tempering of Magnacut and they're ****. So that means I'm left with M4. Also saw a vid saying in his opinion Spiderco treated the Para2 M4 too low, but that possibly other Spidey models have better treated M4. Is that true, and if so, what model of Spyderco in M4 has the best treatment? I am thinking of Native 5

Has anyone attempted to keep a good edge (toothy, not mirror) on M4 using the Sharpmaker? Or K390? I know K390 isn't tough at all, but maybe I want one just because of how cool it is. I have a Sharpmaker from 2013 with the two regularly supplied triangle stones (medium and fine), plus also diamond, and Ultrafine. I use it to sharpen my blue #2 Santoku.

Like others have said CBN rods will do the trick. I wanted to add that if you are seeing chipping change your edge geometry. Going from 15dps to 20DPS will have a dramatic effect on edge “toughness” and you will have less chipping.

I have heard that edge geometry plays as much or a role or more than they type of steel when it comes to toughness. To find what works best for your use case is just to sharpen it a few DPS higher if you get chipping. Once the chipping has stoped or minimized then you have a good angle for your use case.

[Steeltoez83]

I tested about 15 spyderco steels and how resilient they would be to low volume but hard impacts on the edge. In controlled testing I didn't compensate for lateral forces in cutting. That usually happens when the user requires more force to finish the task at hand. The overall winner was the polestar in bd1. It beat k390, m4, rex45, n690, h1, s110v, s30v, s45vn, vg10, cruwear, maxamet, xhp, and s90v. Id still recommend setting fresh apexes often for the first few edges to remove any stressed/fatigued steel. The factory edge is the most susceptible to damage. Most of the time I just cut it off on a stone and set a fresh apex. And you can always adjust to a higher edge angle if your needs require it.

[Skar]

Want to answer directly to m4 in a hard use folder, the Gayle Bradley 2 is hard to beat. I’m sure it can handle anything you throw at it.

I use a ceramic and diamond guided sharpener, that works well for all the knives I’ve put against it.
I don’t use a sharp maker so I can’t speak to it’s performance.

[DunninLA]

OK, so if I'm not mistaken, Spyderco's generally ship with about a 36 degree bevel, right? I'm thinking that is a good geometry to support toughness, correct? And that to reprofile to 30 inclusive would be a mistake for a tool knife. And in fact it could be preferrable to take the 36 from the factory, and put a 40 microbevel on it? And I could do that quickly with maybe five minutes of light strokes on the Sharpmaker diamond rod?

The thing with the Sharpmaker is that you pick 30 or 40... nothing in between or outside. So I want to make sure that picking 30 or 40 works with the Sharpmaker, and it sounds like with diamond rods it will.

[Cl1ff]

A Rex45 Native is still available from GPKnives for a really good deal ($112).
Rex45 is really similar to M4 and probably a good option for you. That’s the simplest and probably best way to go, in my opinion.
TripleBHandmade has some good YouTube videos and threads here testing these steels.

As others have said, the MagnaCut Native is becoming available and there are already some threads here showing off a lot of promising testing.

I think Spy27 is another good option for you that the Native 5 is available in. It has held up really well for me on my Native during normal use and through my abuse of the the Spy27 Mule with a straight spine. No chipping or rolling after many tests and the damage I did get from tapping and scraping the edge on concrete and metal was pleasantly minimal. I just sharpened it like normal and all the damage was gone and I’m to get hair shaving edges easily (using both the CBN and ceramic sharpmaker rods and plates from Spyderco). It seems to just blunt rather than suffering significant chipping or rolling.
Spy27 is also really nice to sharpen. I love the really prickly edges I get right off of the 400 or 800 grit CBN plate.

Another thing to consider is that edge geometry plays a bigger role in the toughness of an edge in different uses than steel.

If you want a really tough knife you can abuse, I suggest the saber ground Delicas, Endelas, and especially the saber ground combo-edge Endura. They won’t cut as efficiently as the slicey hollow grind of the Centofante, or the full flat versions, but they are much tougher.

I suggest the combo edge or serrated edge because the serrations are a chisel bevel, so they’ll be more acute than the plain edge. The serrations are also going to make up for the VG10 steel’s mid tier edge retention and toughness. The tip of the serrated “teeth” will protect the scallops that do most of the cutting from wear and damage.
The Sharpmaker makes sharpening serrations easy and VG10 is also nice to sharpen (Spy27 is a CPM American version of VG10 developed to have better performance by Spyderco, but they are both nice to sharpen).

I have my Dad, who is really abusive to knives and often breaks tips and mangles edges, using a saber ground FRN CE Endura that has been holding up well. He still manages to chip the edge near the tip, but not too badly and the actual tip is still there. I think he does a lot of scraping on metal prying, and cutting into dirt.

Anyway, those are my thoughts. I hope they’re helpful.

[DunninLA]

So I have a question about K390. On this site https://knifesteelnerds.com/2021/10/19/ ... esistance/

k390 is not found in the tables for toughness/edge retention / corrosion reistance. So I don't know how tought it is. It seems to be Vanadis 8 with the addition of tungsten and cobalt. Is K390 a lot less tough than Vanadis 8 b/c of the addition of tungsten and cobalt?

[Cl1ff]

OK, so if I'm not mistaken, Spyderco's generally ship with about a 36 degree bevel, right? I'm thinking that is a good geometry to support toughness, correct? And that to reprofile to 30 inclusive would be a mistake for a tool knife. And in fact it could be preferrable to take the 36 from the factory, and put a 40 microbevel on it? And I could do that quickly with maybe five minutes of light strokes on the Sharpmaker diamond rod?

The thing with the Sharpmaker is that you pick 30 or 40... nothing in between or outside. So I want to make sure that picking 30 or 40 works with the Sharpmaker, and it sounds like with diamond rods it will.

You can always try the lower angles and just increase them until you’re getting the performance you want.
For example, if the approximate factory angle ends up not taking damage, you can try to go lower for better cutting performance. If it takes damage, you can go a little higher.

The Sharpmaker CBN rods will put a microbevel on anything quickly. They’re a little slow to reprofile with, but maintaining the angle or putting a microbevel on it is very quick.

That’s my experience, at least. There are lot of people here much more skillful and knowledgeable than me that could chime in with a lot more good information or tell me I’m wrong, though.

[DunninLA]

I'm pretty sure the people here who are "more skillful and knowledgeable" have never depended on just a Sharpmaker, so I'm really depending on novices who have used Sharpmaker on M4, K390, and other tool steels with 4% or higher Vanadium.

[electro-static]

Honestly Diamond plates do me well, I really love worksharp’s benchstone with upgrade kit. The tilting plate and angle guides really make sharpening easy.

[Bill1170]

For plain edges without recurve, diamond or CBN plates are much faster than the Sharpmaker for reprofiling or removing chips. I use the Sharpmaker for PE maintenance and for everything with serrated edges. I use it with the CBN rods for reprofiling serrated edges.

[wrdwrght]

Doing M4/K390 touch-ups on a Sharpmaker is one thing, reprofiling another.

Sure, diamond/CBN rods can speed up Sharpmaker reprofiling, but I have found them to be a small answer to a big ask, especially on harder steels. I prefer benchstones for reprofiling.

Some will say benchstones are problematical for getting the desired angle. I would ask why you would be into reprofiling if you don’t already know how to achieve the desired angle.

A Sharpmaker will certainly get you on the right road to discovery.

More sophisticated guided systems just don’t require this discovery. And so, knife-sharpening has become overmuch and unnecessarily involved, unless, of course, splitting hair is your minimum metric for what is sharp.

One of the many reasons the edge is a ghost is that we can’t agree on what sharp enough is.

[Sharp24/7]

I’d spring for a guided system. You can always practice freehanding on the stones, but you’ll have something to fall back in in the meantime. And from my experiences reprofiling, a guided system is just more practical.