Masamoto VG Gyutou 240mm - Sharpening Help

The knife is a Masamoto VG, not VG-10.  If they were ever VG-10 they became something else several years ago.  Korin is the only retailer I know of that calls the knives VG-10 -- who knows why.  Cook's Illustrated still lists them as VG-10, presumably because they don't know any better which should tell you plenty about CI's knife review competence. 

The VG is a truly wonderful knife, even if CI it and gave it a "best" endorsement.  Congratulations on getting one. 

The EP is a good system for newbies whether or not they're engineers.  It has its limitations, but you probably won't bump against any of them. 

You don't need a full on Chosera set, but since I don't follow EP pricing all that closely I'm not prepared to call it a waste of money either.  Choseras are definitely good stones, they have some drawbacks besides being overpriced but they won't likely effect you.  Similarly, their greatest advantage is speed and that doesn't count for much on an EP either.

The VG will take and hold a polish at the polish at the 10K level, but I'm not sure that the Chosera does any better job than either Ben's sharpening tapes or the comparable Shaptons.  The best solution may be tapes leading to one or two stones.  If you have questions try calling Ben (Mr. Dale). 

Once you've got the EP reasonably well figured out -- a process that will require you to sharpen four or five knives -- "opening" the VG won't be much of a problem.  But, it's never a bad idea to have a knife sharpened by someone who really knows her (or his) stuff.  My first choice in sharpeners for a chef's/gyuto is Dave Martell at Japanese Knife Sharpening.  Carter's sharpening services are equally fantastic.  Ken Schwartz is just as good with those types of knives -- you can contact him through Chefs Knives To Go (and tell him "hi" from BDL, and same for Dave). 

70/30 is not magic symmetry for the VG, (again) despite what Korin says.  It appears Masamoto sharpens its western handled knives by sliding them across a grinder until they develop a burr on one side, then turning them over and sliding them across the other bevel until the burr flips back. The result is roughly twice as much bevel on one side as the other, and an edge that's good enough to fool around with until you can get the knife properly sharpened.  I call it a Christmas Morning Edge.

It's my understanding that Masamoto anticipates most users will end up with something very near 50/50.  But what they think doesn't matter much.  It's your knife. Sharpen the knives to whatever degree of asymmetry you like.  The ratio of the right side bevel to the left will tell you the symmetry.  Dude, it's just trig. 

I forget just how adjustable the EP is (or isn't).  You can sharpen each bevel to something more acute than 15* without many problem.  Anything steeper than 10* is probably pushing it.  Sharpen both sides at the same angle.

The more asymmetry the sharper the knife will act, the less likely it will be to wedge, the less durable it will be, the more it will tend to "steer" when used by someone who's wrong-handed.  If you sharpen the knife more assymetrically than 2:1, you limit your ability to use a steel for maintenance because of the way the pressure from the rod will cause the shearing force to bend the edge where it's weakest, causing it to fatigue too quickly.

Hope this helps,

Enjoy,

BDL

 

Don't worry about the VG - VG-10 thing.  Like I said, it comes from Korin.  They've got a few pieces of misinformation they absolutely won't let go of, an excellent sharpener with a few strange opinions of his own, but are in every way an estimable outfit.

One of their peccadilloes is to recommend against using a steel for any Japanese knife.  Unless you're sharpening the VG to a high degree of asymmetry, you want to use a rod hone (aka steel).

How asymmetric should you sharpen it?  If the knife will be used by only one person, or everyone's same-handed, and you value a slight increase in absolute sharpness over durability, sharpen to no more than 2:1 asymmetry.

If the two of you are other-handed, unless one of you has strong skills, sharpen to 50/50.  Most stores that ship Masamoto wa-gyutos (different handle, same blade shape) sharpened, have them sharpened to 50/50.

My wife is right-handed, I'm left-handed, my technical knife skills are much better than hers, and I sharpen our knives to 60/40 righty.  

In the post you deleted, you asked about determining angles.  I assume you deleted it because trig enlightenment burst over you like a thunderstorm.  If not, ask.   

As to the Choseras, pretty much I wish I hadn't brought it up. 

OK, OK.  I'm whining about money.  When it gets down to it, you aren't saving much if you add a 10K to one of the other kits, and spending more if you add both a 5K and 10K.  Since the VG can take and hold a 10K polish, wotthehell wotthehell. 

With knives and sharpening, there is no best for everyone and probably not even a best for you.  Learning to freehand is not that big a deal. But it is a deal, and I understand and respect your desire not to deal with it.  The EP/Chosera set up will do a great job on your knives once you've got it figured it out -- which won't take long.

BDL

 

CS,

I am sooooooo glad you brought this up.

Right handed asymmetry means that the knife's left side bevel (holding the knife by the handle) is sharpened wider than the knife's right side bevel.  Unsurprisingly, left handed asymmetry results from the reverse.

As a practical matter, asymmetry usually means the apex of the bevels (i.e., the edge) is NOT on the center line.  Almost all knives sharpened on both sides are profiled with the same edge angle on each side, and even more of them should be. 

In engineer speak:  The choice of edge angle and symmetry is all about balancing stress and fatigue against wedging within the context of (material) strengh and toughness.  You want the part of the knife just above the actual edge to be as thin as possible while robust enough to stay "in true" and not tear or chip.

Greater symmetry translates to greater width (and stress resistance) just above the edge.  If you're going to steel (and you should) as part of maintenance, you need a enough symmetry to prevent a stess line from beginning at the bevel shoulder on the short side, running through the center of the knife to at an oblique angle.  If the knife is too thin at the short side shoulder bevel, the alloy will fatigue enough to make it more likely to bend -- or even tear.  If this is unclear, we can go into more detail in a subsequent post.

66.6/33.3 (aka 2:1) is a sort of max asymmetry if a rod hone will be in the picture.  Eyeballing bevel proportions isn't that exact, so shoot for 60/40.  Your knife will still be unbelievably sharp compared to whatever you used before. 

If you're not going to steel, but "retouch" on your EP everytime the knife gets slightly out of true, you should sharpen to the greatest degree of asymmetry the knife can hold.  I'm not sure how far you can push the VG.  80/20 anyway.  I have a friend who sharpened his to a near chisel (call it 90/10) for restaurant use.  It was very sharp, but kind of marginal about making it all the through a service.  He'd recommend it, but I don't.

You'll want to use The Magic Marker Trick when you first start grinding in asymmetry, so you can actually see the bevel shoulders and compare them to one another.  If nothing else, this should reinforce the ideas that you're eyeballing symmetry by rough proportion, as well as the importance of keeping a smooth shoulder parallel to the intended edge.   

By the way, the "included angle" is determined by adding the values of the edge angles.  A 15* edge angle on each side means an 30* included angle. 

The "default" edge angle for most sharpeners doing Japanese knives is 15*.  Better is to sharpen the most acute angles the knife will hold without the edge collapsing too frequently.  In the case of the VG, that's probably just a skosh more than 10*.  It's something you can play around with for awhile.  If you don't want to fool with it, split the difference and set the EP as close as you can get to halving the difference between the 10* and 15* marks as you can.

After four decades, I'm still messing with my Sabatiers.

Bottom Line:

~60/40 righty at ~12.5* (both sides) is a good default.  Alternatively, try 10*, also at 60/40.  If that doesn't hold up long enough for you, sharpen a 15* "primary bevel" on top.  You might really like the way a double bevel combines thinness with durability.

BDL

PS.  Since the question is probably going begging:  I am not a trained engineer.  But have some small background in physics, more of one in math, and picked up a little materials science on the street corner over the years. 

 

Yes.  The wider bevel should be on the right side. 

Yes.  60/40 refers to the ratio of the bevel widths   If, for instance, the right side bevel was 9 mm wide, the left side bevel would be 6mm.  It is not important to measure the bevel widths to any great accuracy, the Mk IV GI Eyeball will do well enough. 

It depends.  Bevel width would be proportional to the amount of material removed if you were starting with an unsharpened knife.  Otherwise not so much.

No.  You may not confidently assume that the number of strokes will be  proportional to the desired bevel width or amount of material removed.  There are too many variables.  You must measure the bevels -- either by eye (which should be good enough) or find some other, more accurate method.

You can make the bevels more visible by using the magic marker trick.  Ben has at least one video up on his site or You Tube (I forget which) showing you how.  It's not difficult, you simply paint a 3/4" wide line along the edge with a Magic Marker.  When you sharpen the knife, the Marker ink will abrade off along with the steel. 

The upper demarcation between marker and abraded blade is the bevel shoulder. 

On the lower, edge side of the marker, if you haven't abraded all the marker from the edge, you did not sharpen the edge. 

The bevel shoulder should be an even line, running parallel to the edge from the heel (almost) all the way to the tip.  If the bevel shoulder is uneven, you have high and/or low spots.  The presence of either means the bevel is not flat.  If the bevel is not flat, the knife will tend to bend and break at the weakest points, will not steel correctly, and be difficult to resharpen.  So, you have to grind the high spots down.  You always want a flat bevel before leaving any grit level for a higher one.

Note:  Because of the arc of the tip and the geometry of the EP that arc will most likely be sharpened at a slightly more acute angle than the rest of the blade and consequently have a slightly wider bevel.

To establish your 60/40, right handed, 12.5* edge on an EP: 

Mark the left side of the blade with Magic Marker.  Prep your coarse stone and use it to profile a 12.5 degree bevel just until the Marker is removed from the entire length of the edge. 

"Section" the knife (selectively sharpen narrow areas) as necessary to remove any high spots.

Flip the knife over, mark the right side as you did the left.  Sharpen the right side as before.  When the Marker is removed from the edge, take the knife off the EP's table and estimate the proportional widths of the right and left side bevels.  Return the knife to the table and continue sharpening the right side until the desired proportion is achieved.  

Once your bevels are set, you can continue to sharpen the knife using higher grits in sequence.  It is not important which side you sharpen first, only that you maintain their proportional relationship. 

Continue using The Magic Marker Trick with all your stones for your first few couple of sharpening sessions.  After a short while you'll learn to see and feel the edge bevels without it. 

BDL

 

OK BDL, I think I'm misreading or misunderstanding something (that just might be because I'm a "lefty" /img/vbsmilies/smilies/crazy.gif)

For a "righty", looking at the spline, is the larger bevel, say 60, on the right or the left?

What is confusing to me: I presume that a single bevel (chisel edge) knife for a "righty" has the bevel on the left, correct? The right side is FLAT, correct?

Would that be a 0/100 or a 100/0?

My intuition (which is rarely right /img/vbsmilies/smilies/crazy.gif) says that the narrower bevel should be on the same side as the "hand" of the user, correct?

 

Hi Pete,

OK BDL, I think I'm misreading or misunderstanding something (that just might be because I'm a "lefty" )

We southpaws are different in more than just handedness. 

For a "righty", looking at the spline, is the larger bevel, say 60, on the right or the left?

On the right.

What is confusing to me: I presume that a single bevel (chisel edge) knife for a "righty" has the bevel on the left, correct? The right side is FLAT, correct?

No.  You've got it bass ackward.  Imagine that you were using the "claw" technique with your offhand.  You'd want the flat part of the knife against your knuckles, because the bevel would force the knife to twist. 

Would that be a 0/100 or a 100/0?

Anaylytically it doesn't matter.  As a matter of language, you always put the biggest number first.  For instance, you'd say "60/40 right" or "60/40 left" rather than reversing the numbers to show a different handedness.

I don't use 100/0 as a term, I just call it chisel or hamaguri (depending on whether the back of the knife is flat or concave.  Other people use the term however they want.  In real life, chisel edges aren't truly 100/0 because you have to take enough of a bevel off the back to deburr.  The "clamshell's lip" on a hamaguri is the only truly 0 back bevel I know of.   

My intuition (which is rarely right ) says that the narrower bevel should be on the same side as the "hand" of the user, correct?

Not correct; already described with the "claw" example.

The reason you sharpen asymmetry depending on the hand is wrong-handed asymmetry tends to steer, while correct-handed asymmetry tends to stay square with the board.  The better the user's grip and the higher her (or his) skill level, the less the tendency. 

I -- a lefty with good grip and good skills -- start to fight the knife at around 70/30 right.  My wife is a righty so I sharpen our knives to around 60/40 right which allows us a slightly thinner bevel, helps her a little, but doesn't make it awkward for me.

If you or I were using a right-handed chisel or hamaguri edged knife, with a thick body above the blade road, sharpened to a very acute angle, and with a consequently very wide bevel, the angled bevel really would push the knife off making thin cuts difficult, and also cause the edge to rotate away from the claw.  The example was more than hypothetical. 

BDL

 

This is a bit of an old post and I hope people don't mind me reviving it.  I too have a Masamoto VG gyuto (240mm) and have an edge pro on the way.  I am confused by what's in play when we're talking about dealing with assymetric bevels.  Korin's sharpening guide says that when freehanding, the right side of the knife should be lifted to  two-coins' height and the left at three coins' height.  It also says that the right side should get roughly 7/3 the amounting of sharpening that the left side is getting.  As I understand the advice in this thread, when sharpening a Masamoto gyuto on an EP, one should use the same angles on both sides (12.5 degrees was suggested) and shouldn't grind the right side any more than the left.  If neither of these are being done, how does one preserve the asymmetric pre-set (presumably 70/30 bevels) on an edge pro?  And how is that squared with Korin's advice?

 

This is an old thread put thought I would post this for anybody looking for the same answers I was when I found it:

I recently purchased a left handed Masamoto Wa Gyuto 240mm. (actually runs long a bit so glad I did not go for the 270 as my knife skills are not great)

I had to read this a number times to get the sharpening instructions in my head for a left handed asymmetric blade. 

Definitions

Holding the knife in my left hand as if I was going to cut with it, tip facing north:

• Inside face - the right hand side of the knife which faces the user, which is the side that has the logo on it. Eastern face
• Outside face - the left hand side of the knife which faces away from the user, which is the clean side no logo on it. Western face.

Asymmetric Bevel

If you think of single bevel knife the inside face is flat (possible concave or small micro bevel on it), the outside face a big bevel. It it were a chisel the flat side is on the inside face, the chisel point would be on the outside face. The same goes for the bevel on the knife, the bigger larger bevel goes on the outside face, the smaller "micro" back bevel goes on the inside face to keep it as close to flat as possible.

Outside Face

-Angle 12 degrees

-Bevel Size 70/30 approximately 66/33 that is 2 x the size of the inside face or as a ratio of bevel size of outside to inside face of 2:1

Inside Face

-Angle 15 degrees

-Bevel Size 30/70 approximately 33/66 that is ½ the size of the outside face or as a ratio inside to outside face of 1:2

Procedure

I used the Wicked Edge Pro System (WEPS)

I set the outside face angle up using an angle cube and obtained the more acute 12 degree angle from my WEPS by flipping the locking detent screw around to the plain side and tightened up the detent screw with little pliers (which I do normally because they always come loose during sharpening).

I setup the inside face by selecting the 16 degree mark on the WEPS which when measured on an angle cube gave me 15 degrees on the belly and 13-14 degree angle on the tip. Just a word of warning whilst the WEPS has angles marked they are only a guide because the true angle will change depending on blade height and position, it is basic trig really.

Progression

-1000 grit (2000 JIS, 6.7u) diamond stone to set the bevel

-1200 ceramic (5u)

-1600 ceramic (5000 JIS 2.85u)

-Stropped with 0.5 micron CBN paste (I would have used 3.5u paste first but I have nicked the strop badly so skipped it)

I don't have my Naniwa-Chosera 5000 and 10000K Water Stones yet but they are in the mail. 

Bevel Setting

Used a magic marker to eye ball it

-set the outside face first until a good burr and consistent looking bevel for the entire edge

-set the inside face second until a good burr was reached, this resulted in a very small looking micro bevel on the blade.

I then went back and forward until by eye sight it looked like I had a ratio of 2:1 outside to inside face, in reality it is probably closer to 70:30 it is very hard to guestimate even using a belomo 10x loupe

I then run though the progression very little pressure was applied gentle strokes some scrubbing of the tip because of the more acute bevel of the angle, once the bevel was set moved though progression.

Final Result

Will lop hairs on my arm in half without touching my skin, tried dropping a tomato on the blade chopped it clean in half, can slice tomato super thin. Not worked with it for long yet so not sure how durable my edge will be.

 

Personally, I wouldn't bother with different edge angles.  If 15* is acute enough for one side, it's acute enough for another.  My experience with western style Masamoto knives is that they're indifferently sharpened at the factory, and they don't actually bother with different angles either.  Koki's been drinking the Kool-Aid.

70/30 or 66.67/33.33 are functionally the same.  Don't make yourself trying to figure out which is better.   On the one hand, it's about the cheapest and fastest way possible to sharpen a knife.  On the other hand, it's enough asymmetry to give you a performance bonus, while still sufficiently symmetric to maintenance with a steel.  A fair balance in the tension between absolute sharpness and durability.

There's no need to buy a "left handed" knife.  If you can sharpen, it's easy enough to push the bevel over -- especially over time. 

All trig is basic. 

BDL