is your mora too sharp?

[TheGreenMan]

...If you sharpen with the blade going into the stone you will repeatedly make and break off pieces of a wire edge...

This fine honing stage on stones with the edge trailing, or ‘backwards’, if you will, has completely weirded me out, but it is intriguing. I was reading a thread a few weeks ago (I think on British Blades) about Chef''s steeling technique that was featured in a TV programme. He was steeling a knife with the edge trailing which was totally counter intuitive for me, but many of the contributors to the thread said that this would produce a better edge.

I wonder if my fine honing of the zero ground Mora blades on Japanese Waterstones (4000, 6000, 10,000 grits) with the edge leading is breaking off pieces of the wire edge, as you describe it? I usually check the blade between the grits with a hand lens to ensure that the scratches produced by one grit are on every part of the blade, and have removed the coarser scratches from the previous stone before proceeding to the next finer stone. Then, when I’ve finished with the 10,000 grit stone, I occasionally use one of those Norwegian Jasper hones like the one that Spammel has illustrated (only mine’s a plain black stone, and boy does that puppy take it to the next level!), but more usually after the 10,000 stone, I then strop on leather with compound, with the edge trailing. Do you think that this regime would be tearing sections of the wire edge off as you describe?

I have a beech wood carving project on the go, and all of the zero ground Mora knives have chipped and have blunted (when I say ‘blunted’ they’re still pretty damned sharp, with the eception of a Clipper which would now make a good butter knife, but not sharp in terms of a good wood carving edge). Maybe I’ve reached the limit of the 1095 steel and the type of heat treatment employed, and maybe it’s time to try some hand forged carving knifes, or maybe I should try fine honing on stones with the edge trailing, before the polishing stage.

I’ve had an A2 tool steel convex blade chip in one spot on the blade during this beech wood project, and was beginning to think that it was poor honing that had caused this problem, or the zero ground convex being too thin at the edge, but thinking about it, the chip may have been there when I started using it. I may have used the knife previously on some wood with knots, and chipped it on that. Not sure. And the edge of the A2 steel blade is still very keen indeed, and is still able to remove a good amount of material, and cleanly, and seems to be standing up marginally better than a blade of VG-10 (the VG-10 I’ve noticed on previous occasions, strops very well and the edge can be made good with just a few stokes, the A2 by contrast seems somewhat harder than the VG-10 and takes a good deal more stropping).

Incidentally, the A2 steel and VG-10 blades were honed using the ceramic side of a DC4 and then stropped, and not honed on Waterstones as the zero ground Mora knives were, and I haven't stropped either the A2 or VG-10 during this current carving project.

Best regards,
Paul.

 

[Hoodoo]

Paul, I can't answer all your questions because there are a lot of factors involved. Type of steel and the angle of the bevel do make a difference so there are limits to the acuteness of the edge, depending on what you are carving and HOW you carve.

This is from "Swedish Carving Techniques" by Wille Sundqvist.

"For precise carving and detail work, you need to have exact control over the amount of wood being removed. This kind of carving requires that the bevel be flat and not rounded in the least."

"Correct edge angles and bevels are important. What is the correct edge angle? As in the case of other edge tools used for cutting, there is a relationship between the hardness of the material you are working with and the quality of the steel in the knife.Harder wood requires a less acute edge angle. A knife will cut better if it has a more acute edge angle, but only so long as the steel will stand up to the use it is getting. If the steel is too hard for the angle given it, it will chip easily, if it is too soft for a given angle, it will dull quickly. In some cases the proper angle is a matter of the way you carve and how much force you use. The edge angles on my knives range between 22 degrees and 26 degrees."

Of course this is for large carving knives. If you use realy small carving knives (like Xacto style blades), you will want much more acute angles. Keep in mind that the more acute the angle, the less resistance you will have and the less pressure you will need to use. That's why techniques for sharpening and using knives are not written in stone. Every knife, especially custom knives, is unique. Different steel, different bevels, different heat treats. Some knives NEED a secondary bevel. I can say from experience that many do not.

As for steeling the knife, was that a smooth steel or a sharpening steel? With a sharpening steel, I sharpen with the edge going into the steel. The edge will degrade faster but I'm not carving wood with it so it really doesn't matter and what I'm interested in is a toothy edge. And I can bring the edge back with just a couple of swipes. This assumes I'm not using one of those kitchen knives with super duper steel. Most of my kitchen knives are made with relatively soft carbon. Now if I'm using a smooth steel, which is used mainly to ALIGN the edge, then I use that with the edge trailing.

As in all things, just experiment. If you rely solely on the experts, then just drink the Kool Aid and be done wtih it. If you experiment on your own, then you can come to your own conclusions based on your own experience and find out what works for you...but still keep an open mind eh.

 

[TheGreenMan]

Paul, I can't answer all your questions because there are a lot of factors involved. Type of steel and the angle of the bevel do make a difference so there are limits to the acuteness of the edge, depending on what you are carving and HOW you carve.

This is from "Swedish Carving Techniques" by Wille Sundqvist.

"For precise carving and detail work, you need to have exact control over the amount of wood being removed. This kind of carving requires that the bevel be flat and not rounded in the least."

"Correct edge angles and bevels are important. What is the correct edge angle? As in the case of other edge tools used for cutting, there is a relationship between the hardness of the material you are working with and the quality of the steel in the knife.Harder wood requires a less acute edge angle. A knife will cut better if it has a more acute edge angle, but only so long as the steel will stand up to the use it is getting. If the steel is too hard for the angle given it, it will chip easily, if it is too soft for a given angle, it will dull quickly. In some cases the proper angle is a matter of the way you carve and how much force you use. The edge angles on my knives range between 22 degrees and 26 degrees."

Of course this is for large carving knives. If you use realy small carving knives (like Xacto style blades), you will want much more acute angles. Keep in mind that the more acute the angle, the less resistance you will have and the less pressure you will need to use. That's why techniques for sharpening and using knives are not written in stone. Every knife, especially custom knives, is unique. Different steel, different bevels, different heat treats. Some knives NEED a secondary bevel. I can say from experience that many do not.

As for steeling the knife, was that a smooth steel or a sharpening steel? With a sharpening steel, I sharpen with the edge going into the steel. The edge will degrade faster but I'm not carving wood with it so it really doesn't matter and what I'm interested in is a toothy edge. And I can bring the edge back with just a couple of swipes. This assumes I'm not using one of those kitchen knives with super duper steel. Most of my kitchen knives are made with relatively soft carbon. Now if I'm using a smooth steel, which is used mainly to ALIGN the edge, then I use that with the edge trailing.

As in all things, just experiment. If you rely solely on the experts, then just drink the Kool Aid and be done wtih it. ...

That’s a sage and helpful reply, maesto, I’m much obliged to you.

As far as I can remember, the steel looked like the sharpening kind and not the smooth polished type for realigning a thin edge.

...If you experiment on your own, then you can come to your own conclusions based on your own experience and find out what works for you...but still keep an open mind eh.

And that’s very much my method of research.

Kind regards,
Paul.

 

[TheGreenMan]

...how do I get a secondary bevel on the edge of my knife?...

Just to add to what others have recommended, I find that if you are using a small pocket stone, in this example a DC4 (works just as well with a Spyderco Double Stuff pocket stone), then turn the knife upside-down, holding the knife still, and run the diamond side of the whetstone back and forth along one edge, until you can see a small bevel, then do the same to the other side of the blade, then with a hand lens check that the bevels meet all along the edge. If they do, flip the whetstone over and repeat the same steps with the ceramic side of the whetstone. Feel with the pad of you’re thumb for any burr (wire edge) and if you can’t feel any, then look again with the hand lens to check that you have honed the bevels along their length and removed all the scratches made with the diamond side. Then, in the more usual manner (keeping the stone still, and moving the knife) give each side of the blade a few swipes diagonally across the ceramic side of the whetstone, edge leading. The secondary bevels are now ready for stropping to give it a good polish. Moving the stone along the blade edge while keeping the blade stationary can be a little easier to control the angle of the micro bevel when freehand sharpening. Eventually, with more stropping if the secondary bevels are micro bevels they will quicky become convexed.

That said, Hoodoo’s recent advice to hone on a stone with the edge trailing has thrown my whole honing world upside-down!

...I have to admit that I do not now use waterstones to sharpen my knife - too many complaints about the mess on the kitchen table from high command...

And would this arrangement help to keep the domestic peace with ‘high command’?

Damp cloth on work surface and between the tray, and another damp cloth between the tray and the Waterstone (the damp cloths prevent everything from sliding about), water for irrigating the stone in an old washing-up liquid bottle (less messy than sprinkling the stone with water), and the tray prevents large puddles of slurry laden water accumulating on the tabletop and running onto the floor. Nice and cheap too!

Best regards,
Paul.

PS: And try not to spill tung oil all over your Waterstone like it did with this one ...more expense!

 

[Hoodoo]

I had to go back and watch Mor's video to refresh my memory on his sharpening technique. He spends a lot of time railing against the secondary bevel. At the very end, before he strops the blade, he VERY LIGHTLY strokes the blade at a greater angle on a smooth kitchen tile, creating a MICRO bevel (his words). What he's actually doing is levering off the burr. This is exactly the same thing the sandpaper backed mousepad does in the final stages I mentioned above. A smooth steel does the same thing but I think sandpaper does the best job, because you are not just prying the burr off, you are still sanding it off. As Mors points out, you do not put a secondary bevel on the knife like we see with the factory model, but you end up with a tiny convex micro bevel shaped like a church window (Mors' description). This is exactly what occurs when you use a mousepad at 1500 or 2000 grit. You get a very tiny, convex microbevel and no wire edge. Well, SEM photos really show that you NEVER really get rid of the jagged edge. The jags just get smaller and smaller.

BTW, here's the text on sharpening from Wille Sundqvist's book:

 

[TheGreenMan]

I think post #25 is as close to a definitive one for honing of a Mora as I’ve ever seen.

And if any one would like to look at some SEM images of the mentioned ‘jags’ then there is an excellent document for download in the Downloads section of the site. The document is called Experiments on Knife Sharpening.

Best regards,
Paul.

 

[Wallenstein]

From the article above, it sounds like the majority of this discussion is for bushcrafters who use their knives for intricate, delicate carving work?

For those of us whose knives are likely to be used for "general" campsite duties - chopping ropes, carving a tent peg, splitting kindling etc - is this level of attention to achieving a shave-sharp, perfect edge always worth the effort?

Clearly a sharp knife is a good knife, but there must be a point at which the extra hours spent honing, stropping, polishing etc will be undone by one hefty whack with a battoning stick?

 

[Hoodoo]

Well, firstly, why a hefty whack? Why not a light tap? Secondly, I side with Calvin Rutstrum when he says that "A good knife is a fine instrument; it should be properly used and then carefully sheathed."

Thirdly, just about any half decent knife can be sharpened to shaving sharp, including 1/4" inch prybar knives with large obtuse secondary bevels. Shaving sharp means nothing out of context. Fourthly, whether you are talking about thin blades or thick blades, zero grinds or secondary bevels, the edge will not last very long on any of them even with moderate use if you don't get rid of the wire edge.

True, one of the advantages of having a steep secondary bevel is that it's a lot easier to get rid of the burr. I won't dispute that. And yes, the edge will hold up better when it comes into contacts with things like knots or bone. As in all things, there are trade-offs. Ultimately you have to go with what you feel most comfortable with and what works for you.

 

[TheGreenMan]

From the article above, it sounds like the majority of this discussion is for bushcrafters who use their knives for intricate, delicate carving work?...

Actually, the discussion is about achieving an edge on a Mora knife that can be used for finer carving and that has a more durable edge, so that it may also be used for ‘"general" campsite duties - chopping ropes, carving a tent peg, splitting kindling etc’, to quote your own words, and without reaching premature blunting when used for those types of task.

... For those of us whose knives are likely to be used for "general" campsite duties - chopping ropes, carving a tent peg, splitting kindling etc...

It seems a pity to start to confuse the issue by introducing obtuse phrases such as ‘those of us who like to use knives’, when Robin has helpfully raised the specific issue of the Mora knife, and Hoodoo has brought that discussion to the point of perfect acuity and understanding.

It has become apparent to me, and almost entirely due to Hoodoo’s post’s, that, the premature blunting that has occurred with my Mora knives during my current seasoned beech wood carving project, is not that they hadn’t been properly honed to remove the wire edge, but that the zero grind I had given them is unsuitable for removing large amounts of material, in the initial stage of carving, when a grind with a secondary bevel would have been more robust, and would have more likely had a greater longevity.

...- is this level of attention to achieving a shave-sharp, perfect edge always worth the effort?...

That’s a matter of judgment that can only be left to the individual to decide.

...Clearly a sharp knife is a good knife, but there must be a point at which the extra hours spent honing, stropping, polishing etc will be undone by one hefty whack with a battoning stick?

It may take hours to regrind a Mora knife 'flat' bevel, that has a secondary bevel to a zero grind (A Mora knife is more usually slightly hollow ground with a small secondary when new), but it only takes minutes to put a secondary bevel on a zero ground blade and then hone that secondary to a high polish. And whether that honed edge will stand up to batoning is dependent on a large number of variables, such as (if we are generalising beyond the Mora types, or even within the various types of Mora knife!), the angle of the primary grind, the angle of the secondary grind, if it has one, how successfully the wire edge was removed in the later stages of honing/polishin, the type of steel and the heat treatment that the steel has had, and the specific material that is being batoned.

Generalisation, is, generally speaking, an unhelpful thing to do, and specifically if one is interested in specifics

With respect,
Paul.

 

[TheGreenMan]

...Thirdly, just about any half decent knife can be sharpened to shaving sharp, including 1/4" inch prybar knives with large obtuse secondary bevels...

Here’s an example of that very thing. This is RM breaking all the rules of convention by fine shaving wood with a very thick blade with a full height flat primary, and an obtuse angled secondary more suited to a meat cleaver. The absence of truly white knuckles suggests to me that the wood was a carefully selected piece of low density, with a nice straight grain structure with little or no interlocking…I guess this is another example of what can be achieved with finesse.

Kind regards,
Paul.

 

[Wallenstein]

Eeek!

Apologies - wrong thread for my post.

Will phrase things better next time.

 

[Hoodoo]

A secondary bevel can actually do a nice job of "rolling" curls from wood. If you've ever read "Whittling Twigs and Branches" by Chris Lubkemann he makes that very point about carvers who can't get the curl in their rooster tail because of the long thin flat bladed carving knives they use. For curling rooster tails, he prefers a slight convex bevel on his knife. In other words, a secondary bevel that's been convexed but not flattened.

Still, for in the woods, I prefer the nice easy and consistent planing action of the flat scandi bevel.

 

[TheGreenMan]

Eeek!

Apologies - wrong thread for my post.

Will phrase things better next time.

You've done nothing to be upset about, we've all done it a some point or other, me more than most

Kind regards,
Paul.

 

[TheGreenMan]

...If you've ever read "Whittling Twigs and Branches" by Chris Lubkemann...

It's one of my favourites

...Still, for in the woods, I prefer the nice easy and consistent planing action of the flat scandi bevel.

This is fun, ain't it?,
Paul

 

[xavierdoc]

Generalisation, is, generally speaking, an unhelpful thing to do, and specifically if one is interested in specifics

I might have to borrow that one! Is it your own?

 

[TheGreenMan]

I might have to borrow that one! Is it your own?

To the best of my knowledge, that phrase is entirely of my own creation, and feel free to quote it as often as you need, Xav

Cheers,
Paul.

 

[robin wood]

Gosh I am surprised how much interest there has been in this, thanks everyone for the thoughtful contributions.

I have been thinking on this one whilst in the workshop today and was planning posting the pics from Wille's book so thanks for that Hoodoo I think they are useful and this zero grind and hone perfectly flat on the primary bevel is exactly the sharpening that I have done for my last 10 years but I am a woodcarver and so is Wille. It might be worth pointing out that the "Mora" in Wille's book and Hoodoo's photo is what we now call a Mora classic and the grind pictured was intended to be flat scandi but due to the manufacturing technique in the late 1980's tended to have a very slight convex, it is a different knife and a different grind to the knife most folk call a mora today.

I think Wallenstein has a very good point, most people are not using their knives solely for precisely controlled woodcarving but for a range of general uses. What is best for them? Is it the zero grind? Is it zero with a tiny microbevel whether convex or whatever?

I have not spent a great deal of time working with a knife with a very small secondary but the majority of Scandinavian blade manufacturers from factories like Frosts to top smiths like Hankala or Paol Stroud supply their general purpose blades this way, carving knives are supplied zeroed. Here are two easy methods to find if your blade has a secondary or not. First get a strong directional light source shining off the primary bevel, then tilt the top of the knife gently away from you, if it has a secondary you will see it light up as in my picture of the clipper. Second lay the primary bevel on a flat surface say a piece of planed softwood, tilt the wood so teh knife has a little weight pulling it allong the surface and gradualy lift the back of the knife. If you have a genuine zero grind the edge will bite instantly, if you have a secondary you will have to raise the back more as in Wille's illustration to get it to bite.

Now as I see it the major benefit of sharpening with a small secondary is that you do not have to spend all that time polishing the primary. If we look at Wille's illustration again think what good is it doing me having spent all that time polishing the primary?

If the edge is actually created by the secondary...I don't mind what we call it, micro bevel micro convex...or how we create it..couple of strokes on a sharpmaker, emery on a mousepad or whatever the primary is playing no part in the edge all it is doing is thinning the blade down to a suitable thickness to apply the small secondary...so if that's the case why not do it quickly with a coarse stone. Now take a look back at the factory ground clipper...see how coarse the primary grind is? I have been experimenting with this, coarse grind the primary quickly then put on the polished secondary at your desired angle with your desired tools. It is not the best tool for very fine carving but it will carve well as Green mans RM picture shows, here is a feather stick I just did with a knife sharpened this way.

The benefit to me of this grind over a flat scandi is that it takes literally seconds and is very easy to touch up in the field. So my solution is to buy a Frosts 106 flat scandi carving knife for carving and a Clipper or posh knife with a 20 degree grind and a 30 degree secondary. Put the secondary on how you like, sharpmaker looks perfect to me though I use stones myself as most of my knives are carving knives.

Edit,
not sure I made it clear but as far as I am concerned it is the edge angle that is important in terms of edge holding ability, a 30 degree will stay sharp longer than a 20 degree on the same steel, temper etc. Whether we achieve that 30 degree by doing a 20 degree primary and a 30 secondary or by regrinding to a 30 degree flat, the edge will be identical. The flat will carve better because you have the support of the bevel but the primary plus secondary takes a fraction of the time to produce and will cut rope, tomatoes and leather better because there is less resistance it is also quicker to adjust so if you put the secondary on at 25 and the edge folds you can easily take it to 27, that is a lot harder with a flat.

 

[robin wood]

By the way like Hoodoo I would also recomend "Whittling Twigs and Branches" by Chris Lubkemann particularly for kids carving, our kids have been quite inspired by it. Lots of projects for carving with a SAK.

 

[Hoodoo]

Hmmm...well, if these thin single bevels are so fragile, I'm at a loss to explain why the edges on these chisels don't crumple when I pound on the ends with a mallet. Seems like they've been doing it for centuries too. Itza puzzle.

 

[Shinken]

So many factors here guys,

Lets not put all of this in a box, i have a knife in cpm 3v which i can zero and it will be stronger than a knife with the same primary grind and with a secondary that is made of en42.

thats just one factor (steel) learning to polish the edge with minimal wire is another, the material being cut is another etc etc

I think part of learning to sharpen is to listen to the particular knife and steel and what you use it for and find a method that suits you and works for you.

This is a great thread Robin because it gets us to all think out of the box, variety is the spice