Sharpening question - this one is new I think

A

AlonzoMosely

Joined
Aug 18, 2002
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250
I've had a Sharpmaker for about 2 years now. I've had a Lansky diamond and a Lansky deluxe for about a month and a half. I have Buck ceramic sticks. I have read dozens of sharpening threads on bladeforums as well as the Joe Talmadge sharpening FAQ. I know the magic marker trick. I can (usually) get a knife sharp enough to shave hair on my arms. Most people I know think I am intelligent, so I don't think that I am a moron.

Here is my problem:

I got a CUDA arclite today. (420HC). I only got it because I wanted to try a cord wrap on it. But I noticed it wasn't very sharp compared to out-of-the-box sharpness of my Maxx Bowie, EDC 154CM, and CQB Jr. So I decide to sharpen it. I tried touching it up with the Sharpmaker. No luck, I gotta reprofile. I use the Lansky on it (25 degrees). I work on this thing for like an hour and a half with a regular extra coarse stone and a diamond coarse stone. The problem is, on one side of the blade, the magic marker is not removed at the very very edge. I stroke and stroke and stroke (no perverted jokes please), but on the one side, I simply can't get the very top of the edge - a very thin edge of magic marker is still there. So I go through all the Lansky stones at 25 degrees. The very thin strip of magic marker is still there on one side, but I decide, maybe I'll get it with the Sharpmaker 40 degree once I am done with all the Lansky stones at 25 degrees. But I still can't get to the edge on that right side of the blade after going though the Sharpmaker brown and white stones at 40 degrees. And, consequently, the knife is very dull and won't shave hair and takes much more effort to cut through 550 para cord than any of my other knives.

Any thoughts as to what my problem could be here???
 
my thought is, if the magic marker is still present on the edge, you simply haven't removed enough metal yet to bring your edge bevels together. if you're saying that the marker closest to the edge is in fact gone, then i'd say you're not raising a burr. i've sharpened some knives for 2 hours+ before finally taking off enough metal to bring the edge in, so you're not necessarily having a problem yet. i think that thin line of marker remains because your initial angle is not quite there.

go over the usual steps and you should be there. sharpen one side of the blade until you've raised a burr across the entire edge; then flip 'er over and repeat until you raise a burr the other way. only at this point are you ready to move on to a higher grit of stone, and gradually break the burr down to a fine edge. again, don't bother moving on to another stone until you've worn the marker off with your coarsest.

abe m.
 
Perhaps if your'e having that much problem, the blade doesen't have good edge geometry, hold it upside down (edge up) eye level with the tip pointing away from you and see if it has the same angle on both sides, perhaps you have already done this! Dont mind me just jumping in here to visit a little.

Regards;Dwaine C. ....... www.airkatknives.com
 
Sounds like maybe the initial bevel was way out of whack, and you still need to remove more metal on the one side. If you can, get one of those cheap handheld microscopes like Radio Shack sells.... sometimes it tells a little more than the marker trick does. If not, try sharpening on the Lansky at 30 deg. (if nothing else just to give you the satisfaction of putting some kind of edge on it) this may also give you an indication of how much more metal needs to be removed.

One thing I've learned about the Lansky is that when there is a lot of reprofiling to do.... it is slow going. You might pick up a 6x2 coarse stone to work it off a little faster. Also 40 deg. on the Sharpmaker is only 20 deg. a side.. so going from the Lansky to the Sharpmaker in this case won't help. (Sometimes that's confusing, mostly to me). Plus the Sharpmaker is slower than the Lansky at reprofiling.

Hope this helps
 
OK, for one, I was confused about the sharpmaker angle and the Lansky angle - I see now how going from 20 Lansky to 40 Sharpmaker doesn't help me a whole lot. I started from scratch with the Lansky at 25 degrees, and touched it up with the Sharpmaker at 40. This got me shaving sharp - one pass takes off all the hair on a patch of leg. I guess it was just a matter of expectations - I thought with a Lansky it would not take 2+ hours to reprofile a blade, but I guess it does. Anyway, thanks for your comments which gave me the encouragment to keep trying instead of just throwing the arclite in the trash out of frustration. (though I do think there is something wrong with the initial bevel - one side of the knife has a larger edge than the other, and I don't think that I created that problem since the Lansky should be pretty consistent on each side.)

-Alonzo
 
Well done. You stuck at it. More and more blades seem to be leaving their factories with edges sharpened around 25°. I think manufacturers prefer this as they get less complaints about bent and chipped edges if the ground at 15°.
Also far more care and skill is required at the manufacturing stage to ship edges at 15°. The thickness just behind the edge has to be allot thiner and this takes more time and care. They can not afford to burn and edge and loose temper.

Just imagine how long that job you did would take with the Sharpmaker.
 
Hey, you think you got problems? I bought a Camillus EDC with a similar blade shape, but 154CM alloy. This is a lot harder to hone than 420HC. I knew it would take a long time to get the sort of edge I wanted if I used a ceramic rod hone. On the other hand the recurve contour of the blade really dictated a narrow or rounded hone. What I got for knives like this is an Ultimate Edge oval diamond steel. This not only did a great job of reprofiling this blade, it also did a great job reprofiling an AG Russell EDC and an AG Russell Arclite (both with D2 alloy blades).

http://www.knifecenter.com/kc_new/store_detail.html?s=UE12W

You were working with two disadvantages. One is that you weren't using diamond hones and the second is that you were using short hones. You should really get yourself a longer hone with a quicker cutting grit for serious reprofiling.

PS. Your problem is very common. People commonly don't want to believe that they haven't removed enough material and give up mystified. The "always raise a burr" and magic marker trick are just a couple suggestions to break through the denial that you just aren't there yet. Neither technique is necessary if you just believe your sense of touch on the edge or your failed sharpness tests. The trouble is that even after you have been down this road a thousand times, you still get surprised by a blade that needs more work than you expect.

One key to success is never, never, never progress to a fine hone until you basically get the blade sharp with your faster cutting medium or coarse grit hone. Until you get an edge that cuts paper with your faster hone do not (I repeat, do not) advance to your fine hones. Automatically going through a sequence of hone grits via a blind formula will cause you to waste your life away polishing parts of your bevel that are remote from the actual edge with fine hones that will never get you where you need to go.
 
Jeff, how do you get the correct angle on that sharpening steel you linked to? Just eyeball basically?

Also, I must say now, that 420HC Arclite has taken a MUCH sharper edge than the CQB Jr which is multiples of the price of the Arclite. The CQB is hair shaving sharp, but only after multiple passes with substantial pressure. The Arclite is shaving sharp now with one pass and very light pressure. Why the heck can't these things come from the factory that sharp when they've got all the expensive power belt sanders and such???
 
There's the easy way and then there's the way I actually do it. The easy way would be to attach the diamond steel to one of the Sharpmaker ceramic rods with rubber bands near the ends. Just insert the rod into your 15-degree (labeled as 30-degree) slot and hone until you start to get a burr. Then put the rod in the opposite 15-degree slot and repeat the process until you get a burr on the other side (substitute the black marker approach as desired). If you are like me and want that profile to be at a lower angle you can tilt the sharpmaker by putting a pencil under the end of the base. When you are working on the right-hand rod, putting the pencil under the right-hand end of the base will reduce your honing angle around 2 degrees. When you hone on the left-hand rod you put the pencil under the left-hand end of the base for the same effect.

Now what I actually do is work semi-freehand. This involves a little minor trigonometry. Say that I wanted to put a spacer under the spine of the blade such that it provided a 15-degree honing angle. The sine of 15 degrees is basically .26. If the blade is 1 inch wide I would need to elevate the center of the spine (not the bottom surface of the spine, you need to elevate the point halfway between the top and bottom surfaces of the blade) by .26 inches. If the blade is about .125 inches thick I need to subtract half of that from the amount that I need to elevate the bottom surface of the blade (about .06 inch). The bottom line is that I would need to put a .2 inch spacer (.26 - .06) between the spine of the blade and my hone to achieve a 15 degree angle. This is about the height of a stack of 4 dimes. The way it works out is that each dime thickness is about 3 degrees at a one inch blade width. Since I would like to profile at around 12 degrees per side I want to tilt my blade as if I had 3 dimes stacked under the spine. The actual way that I hold my angle is by pressing my index finger or thumb against the spine of the blade as I work on a horizontal hone. I use the stack of dimes to figure out how much of the side of my finger should extend below the spine of the blade as a spacer as I hone. As I work the side of my finger (or thumb) just barely skims the surface of the hone. After years of doing this sort of thing I seldom actually use the stack of dimes. I am not so much looking for a precise angle as I am looking to create a clean bevel that looks symmetrical from side to side. I work at as low an angle as I figure I can get away with given the blade thickness and grind type. I would guess that 10-12 degrees per side (say 20 to 25 degree included angle) is around what I shoot for when I am reprofiling.
 
I found a good way to hold an angle is to occasionally match the angle up against a wedge of the desired angle. The muscle memory is good enough to hold the angle to about a degree. You can make a wedge out of wood and paint it or order a set from leevalley.com.

Since, you say you didn't get anywhere with the sharpmaker, the initial angle must have been greater than 20 degrees. A while back I calculated the sharpening effort based on the material to be removed, for an edge bevel initially at 22 for different final angles. Turns out, that it requires 8x the effort to rebevel to 12 degrees per side from 22 degree, than it would take to rebevel to 20 degrees (here is the thread http://www.bladeforums.com/forums/showthread.php?t=308430). So you should be expecting to be there for a while, especially if you use anything substantially finer than 220 grit.
 
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