How hard to sharpen is 420HC?

Another Shepherd

Another Shepherd

Joined
Aug 9, 2021
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Grasshopperglock said:
Another friend's knife. Good ole' Buck 110.

When you hear about a particular steel being an absolute pain in the butt to sharpen. It's usually some steel that's a dream to run an edge on. They've never tried Buck's 420hc. It's like grinding glass. There's close to an hour in this knife. I started at 400, refined that with 600. The apex was frustrating, but know, it's true and straight.

I'm not done. Oh No, I'm going to run a 1000 grit over it. Then the strop. If this knife had been M4, I would have been done 20 minutes ago. 420hc sucks to sharpen. But it'll shave a frog after I'm done.
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I have two Gerber Strongarms with 420HC. Consecutive serial numbers. Both measured 25|19 degrees with the goniometer. The other night, I tried to reprofile one of them to 19 DPS. Both knives have combo blades, so there is only about 3 inches of plain edge to sharpen. I was using the TSProf Kadet with TSProf diamond plates. I've reprofiled S90V before with the diamond plates--not a big deal. After about 40 minutes of grinding with the 150 grit on the 25 degree side, I began to feel a tiny burr. After 55 minutes, I had a burr along the entire edge except at the very tip. Not an impressive burr, but I could clearly feel it. Flipped the knife over. About 45 minutes later, I had a burr on the other side. I've never spent so much time on any knife before, even going through the complete 5 plate progression.

Tonight I did the other Strongarm with the Work Sharp Professional Precision Adjust. After 25 minutes with the 220 grit diamond plate on the 25 degree side, I had a small burr along the whole edge except at the very tip. Flipped. About 13 minutes later there was a burr on the other side. Better than the TSProf, but still way longer than I want to spend on a beater. Way longer than I have spent reprofiling S30V, S35VN, M390, S90V.

Conventional wisdom says that steels with low edge retention are easier to sharpen than steels with high edge retention. How accurate is that? Aside from the really cheap blades that crumble when you try to sharpen them.

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Well, it's always thrown around. In charts comparing steels.

With no one asking the big question. What does ease of sharpening really mean?

Looking at the popular, "Knife Steel Guild". 420 steel has ranking of 9 out of 10. Judged by how easy is it to grind on it.

How completely, utterly, Wrong. Everything is easy to grind on. Especially with an angle grinder. Ask my lawnmower blades.

On the same steel list, M4 has a rating of 3/10. And that's a what in the hell are you talking about.

.......


How they assigned the easy is a mystery. Where they got it, mystery. Whoever put that list together has never sharpened the steels on it. 420 should be 3/10. M4 is the 9/10. I guess they were looking at some steel composition chart. Thinking, " Hey, look. There's so and so of so in it. Mark that one down as hard."
 
If edge grinds are extremely thick, then most any steel can be a pain to sharpen, even something like 1095. And if the steel is something like 420HC at relatively low hardness (mid-50s or lower), then the 'gummy' nature of the soft stainless can start clogging stones, which results in that 'glassy' feeling when trying to grind a lot of metal from a thick edge. Use a lubricated stone for that, to avoid clogging the stone.

Ordinarily, Buck's 420HC is a breeze to sharpen - it's one of my favorites in that aspect. It's hard enough at HRC 57-59 to minimize that 'gummy' nature that comes at lower hardness and also makes deburring easier. And with Buck's blades in the post-2000 era, they're also ground thinner and edged at more acute factory edge angles (26-32° inclusive, by their spec). So that makes resharpening a breeze, using a decent AlOx stone (Fine India, for example) or quality diamond hones. Diamond isn't needed for 420HC - but good hones from DMT can leave some impressive and screaming-sharp aggressive slicing edges on Buck's blades in 420HC. One of my favorite edges on my 110/112 blades comes from using a DMT hone somewhere between XC and F (225-600) chosen by preference, then followed with a very minimalist, barely-there microbevel applied with a medium or fine ceramic (Spyderco or Lansky are good). I really like that combination on Buck's 420HC edges.
 
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The powdered steels. Feel powdery when you grind on them. Regular forged steel, is gummy. Like 1095 compared to say, s20v.

Regardless of how hard it is. 1095 will gum up diamond plates. It'll smear across the plate. Powdered steels, don't act the same. It's like they go to powder.

In a world where a person could afford it all. Regular old school stones for forged steels. Diamond for the powered.
 
Speaking of 1095, I've liked Schrade's older blades in 1095. They were hardened up to ~60 HRC or so, sometimes even a little higher, and yet still sharpened easily, even on natural stones (Arkansas). An oiled stone is always best for those - for the sake of keeping swarf suspended. But by 'gummy', part of my own definition of that relates to burring tendencies which are much more stubborn at lower hardness. That, in addition to how the swarf from softer stainless can tenaciously cling to a stone's grit like a wad of gum on the pavement, unless the stone is adequately lubricated. Or described another way: sort of a galling-like adhesion of the stainless swarf to the surface of the hone's grit - even hard scrubbing alone sometimes isn't sufficient in cleaning it off, unless there's a film of oil between the swarf and the grit. At adequate hardness, both of those issues are reduced to a larger degree.
 
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You've all seen demonstrations of magnetism using iron filings. That's what I get from 420HC, S90V, and most everything else I have sharpened. I don't have any 1095. The filings stick to the blade because of static electricity from grinding, but they wipe off easily from the blade and the plates.

Maybe I can find a Buck with 420HC that needs sharpening and see how that goes.
 
I used to always have a difficult time sharpening Gerber's. You are not alone!
 
my experience is with Buck's 420HC and I don't have issues sharpening or maintaning the edges.
 
Another Shepherd said:
[...]
Conventional wisdom says that steels with low edge retention are easier to sharpen than steels with high edge retention. How accurate is that? Aside from the really cheap blades that crumble when you try to sharpen them.
[...]
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Thank you. I've been pounding this drum for years. Low hardness steels are an absolute pain to sharpen, high hardness (and high carbide) steels can be very quick and easy, due to minimal burr formation. Thickness and geometry play a big role as well.

Conventional wisdom is utter BS.

Having said that, I agree with others that Buck's 420HC is very easy to sharpen, they have the heat treat dialed in. Never tried Gerber.
 
Aside from Buck's easily sharpened 420HC, thanks to their heat treat process and somewhat higher hardness, other makers' versions can become relatively easy to deal with, so long as the steel is of good quality (pure, consistent makeup) and heat treat is consistent (for good temper and small grain size) with hardness targeting something just above mid-50s HRC.

I'm more familiar with 420HC than any other steel I've used in general, simply because most of the stainless EDC knives I've carried & sharpened over the last 10+ years are in 420HC from either Case or Buck. Case's 'Tru-Sharp' stainless is 420HC by another name (and they've published that fact). Their hardness target is in the HRC 55-57 range, as compared to Buck's 57-59 HRC target. So, being that Case's version is a bit less hard, it'll show more ductile burrs, which take a bit more work to clean up.

But as with any different steel and figuring out how it behaves, there's a learning curve to sharpening and deburring 420HC. When that's figured out, it just becomes second nature in the sharpening process and is no longer a significant obstacle. Deburring is best done by continuously decreasing pressure in the finishing strokes on the stones, which is more effective than trying to remove burrs by stropping alone. Took me some time to first figure that out, 10+ years ago. I initially tried stropping the burrs away on those blades by Case - but their very ductile nature meant that the stropping just made those burrs thinner and thinner, while still not actually removing them completely. So those extremely thin burrs would just flip back & forth and then fold over the edge when attempting cutting through paper or anything else. That did drive me crazy for a little while until I finally started deburring on the stones using edge-leading passes at incrementally decreasing pressure, past a certain threshold where whatever burr remnants were left could be scrubbed off on a bare leather belt (I use the sueded back side of mine for this), or on my jeans. That, or whatever small fragments remained would be scrubbed off the apex in the first cut through paper. Once I began doing that, my impression of 420HC's ability to take and hold a good working edge changed for the better. I now view either of Buck's or Case's versions to be 'easy' to sharpen, simply because I've become most acquainted with them over some time.

I've never tried a Gerber in 420HC. How their own version responds to sharpening will also likely come down to how well they heat treat it and how pure and consistent their sourcing is for the raw steel. I believe those two factors are the biggest influence by far in resulting quality of any blade in any steel, rather than the particular type of steel itself.
 
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Various sources cite Gerber's 420HC as being 54-56 HRC or 56-60 HRC. Here is a Gerber document, but I do not know how old it is.
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T tiguy7 Ooh I like that little jig. How do you go about getting that one if you don't mind me asking? That'd be real good for some projects.
 
I have a Gerber Strongarm with a straight blade that I bought about 4 years ago. I heard good things about Gerber prior to this and based my purchase decision on that alone. I haven't been hard on this knife at all and it loses its edge easily. I have spent hours sharpening, honing, and stropping this knife. The edge is good enough for crude outdoor tasks like splitting wood, batoning, etc. I expected a better blade for the time and money I invested. In addition, the swage and tip area were out of alignment. I regret buying this knife but...lesson learned.

Hence why I joined this forum. Now I can arm myself with more knowledge and make sure my next knife is suits my purposes.
 
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Alberta Ed said:
It looks like a Razor's Edge Guide. I just ordered one to augment my ancient Buck Honemaster which is getting pretty worn down after four decades or so (dang things just don't last like they usta) ;).
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Thanks for the insight! Yup, it is the Razor's Edge Guide. T tiguy7 actually pm'd me the answer, which was very nice of him. Hmmm, yea I still haven't ordered one because, although I can sharpen pretty much any knife to a level that I'm quite happy with on my KME, I'm still learning on benchstones and want to get the art of freehanding down before I go at it with a jig. Although maybe the jig would help me get the muscle memory for holding a consistent angle as well. I may end up ordering one of those later. Thanks.
 
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