Showing posts with label Sharpening. Show all posts
Showing posts with label Sharpening. Show all posts

Monday, January 23, 2017

Book Review - Primer on Folding Knives

I don’t do too many book reviews, but I’m going to do one now. 
Let me recommend “A Primer on Folding Knives” by Steven Roman.  I think you’ll enjoy this book.  I know I did.






Who is Steven Roman?

He’s a mathematician, currently Emeritus Professor of Mathematics at California State University, but don’t let that scare you.  He’s also a wood worker, pen turner, knife collector and a knife sharpener.  He also likes to write.

The book covers many knife-related topics, like knife companies, opening and locking mechanisms, blade finishes as well as handle materials.  That’s a partial list of chapter one.  Chapter two deals with the complex subject of metallurgy.  As best as I can tell, he’s on pretty solid ground for basic metallurgy.  If you want to find out what elements stabilize austenite or the difference between cementite and aged bainite, you’re going to need a more advanced guide.

Chapter 3 is an intensive look at sharpening. 

Face it, knife sharpeners and knife fanciers come in two varieties: those interested in a working edge and those who want the ultimate edge.  We all fall somewhere on that spectrum.  For my barbecue knife I want the ultimate edge.  It’s never going to be used, just shown off.  But the blades I carry, well, they need to be a compromise between sharpness and durability.  Sharp enough I can cut, but not so sharp the first cut dulls the edge.

Steven suggests trying different edges for different steels and working them to see which edge stays sharp the longest.  By matching edge geometry and sharpening against steels you can obtain the optimal best edge for your use.

Most of us will not do that.  It requires a lot of work, standard cutting tests and plenty of notes about observation on your part.  Most of us don’t take the time or make the effort.  That’s okay.  All we want is a sharp knife.  But if you want the best working edge for a particular knife, you need to put forth the effort.

Oh, just because it’s about folding knives, it doesn’t mean its sharpening ideas don’t apply to fixed blades!


Find a copy of Steven’s book, “A Primer on Folding Knives” and read it.  I think you’ll enjoy it.

Monday, July 4, 2016

Re-sharpening

masking tape tricks
You can barely see the serrated steel edge, the rest is protected by the masking tape
I don’t normally cover the side of a knife with tape to protect it from touching the sharpening stone.

This is a little different case.  It belonged to my mother-in-law who no longer needs it and my wife isn’t sure where it’s going.  She has one and is quite happy with it.  Most of the relatives have one.  Yeah, we gave them as Christmas presents.  She may want to sell it as a used knife. 

I don’t have any problem selling used knives, especially one I know its history of use and abuse.  This bread knife needed a little touch up, and I wanted to ensure a nice appearance. 

Most serrated knives are a chisel grind.  The serrations are cut into one side only.  Sometimes you’ll find only a tiny bevel to remove the wire edge.  When you sharpen a serrated knife you end up with a wire edge along the straight side.

This is easily removed by drawing the knife flat over a fine stone, if you don’t mind the surface scratches.  Enter stage right, masking tape on the blade right above the top of the curve forming the serration.

Since I use a Spyderco Sharpmaker, removing the wire edge calls for me just lifting the blade from flat on the edge of the fine stone a degree or two and back stropping.

I got a nice resharpened edge and protected the finish.  I recommend this to anyone who needs to resharpen a dressier knife.

More 2016 Blade Show news:
By now most of everyone should know Spyderco is one of my favorite knives.  They were the first ones I carried.  The one my wife first carried.  I published my first article about a Spyderco.  Not only that, but I think for the money they are great knives.

I understand Spyderco is coming out with an all new line of kitchen knives.  New steel and new handles, it sounds pretty radical.  My friend at Spyderco tells me she is thinning out her kitchen drawers to make room for the new knives.

Also spied in their prototype display were two throwing knives.  I’ve never seen throwing knives at Spyderco.  I suspect, if throwers come to be, we will not see them until January at the 2017 SHOT Show.  2016 is half over and they and everyone else is still delivering and promoting the new 2016 product.  Most of the magazines already have articles lined up for the rest of the year.  To introduce something so radically new might be missed completely by busy editors and layout demands.

Sunday, January 27, 2013

Chisel Sharp



I discovered I needed my chisel for a woodworking project.  I’m taking a course in hand-cut dovetails.  I need a special saw, which I have courtesy of my grandfather.  The chisel I have courtesy of myself.


I bought it maybe 30-35 years ago.  It’s a Stanley 5/8 inch wood chisel made in the US.  The steel?  Beats me.  I bought it at a time when Stanley stood for quality and that was enough for me.


I took it once to a community theater when I did technical theatre.  We were building a set with lots of doors, so that mean lots of passage sets (aka doorknobs and locks).  I looked up and found a co-volunteer using my chisel to hammer small nails out of wood.  


I’d like to say that he was able to use his hands after a few years to therapy but I’d never hurt anyone that bad over tools.  Fortunately I put a halt to his activity before too much damage had occurred.  I just took it home and kept the damaged edge as a reminder never to lend any tool I cared about. 


Now it was time to rehabilitate that tool.  So I got out my stones.


Just in case you don’t know, most wood chisels are sharpened on only one side.  Hence the term, chisel-grind.  The flat edge lets you cut straight through the wood, while the beveled edge clears the wood away from the cut.  If you sharpened both sides, yes it would be sharper, but it would drift away from the cut line.


I have a nice Norton combination coarse/fine stone I bought years ago.  It’s 11.5 inches long and 2.5 inches wide and I really like that size.  It’s hard to get the right angle for each stroke, but once you get it, 11 inches gives you a lot of sharpening distance.


I oiled it up and started on the coarse side, but it wasn’t taking the metal off as fast as I wanted.  So I switched to my little DMT combo diamond stone.  These stones use water as a lubricant so it’s easy to clean up and store.  I bought the DMT so I could touch up an axe or knife blade in the field.  The coarse diamond worked great, but the relatively small size made the job tedious.  I also thought the ratio of diamond material to open polymer made the effective sharpening area significantly small and reduced the metal removal efficiency.

My selection of sharpening stones
On the left the Norton combination stone; the red is the fine grit. The EZE Lap, and the right is my diamond DMT Combo.
I pulled out my EZE Lap, a six inch long fine diamond stone.  That really took the edge down.  Before long I had worked out all the edge damage and had a nice wire edge. 

Now it was back to the Norton stone.  I continued on the coarse side, which made finer marks than the fine diamond EZE Lap.  I guess it makes sense.  The coarse stone is less abrasive than the fine diamond.


I first flat polished the wire edge away on the back of the chisel and did a second uniform one across the chisel’s edge and moved to the other side of the Norton stone, the fine side.  ("Come to the fine side Luke!  I am your father…") Again I removed the wire edge and repeated the sharpening until I had a third wire edge.  I carefully polished the back of the chisel and was finished.

Almost a perfect job, the right edge isn't perfect, but it's very good
It's a pretty good edge, but the right tip isn't perfect.  I suspect its part of the way I put pressure on the chisel during sharpening.

Did I get it sharp?  I think so.  I shaved a few curls from a block of yew wood I had in the basement and was very happy with its action.


Sharpened chisel shaves yew wood
I shaved a few small shavings with my chisel.  I wanted to see how thin I could make them and how much effort it took.

Could I get it sharper?  Maybe.  Depends on the steel.  I could have gone to an ultra fine polish and left the face mirror shiny.  But would the edge hold up?  Steel for chisels is selected for impact and bending properties not necessarily hardness or even edge retention . Some woods are so hard the best you can do is to slowly remove a 32nd inch thick shaving at a time.  Most woodworkers would rather have to resharpen more often than break a chisel.


I’m happy with the way this sharpening project turned out.  I got a uniform edge at about 25 degrees, with a straight, sharp cutting edge.  

In the spirit of complete honesty I used a little wheeled gismo that holds the chisel at a constant angle.  I don’t have any idea where I bought it, but for sharpening a chisel or wood plane blade, it’s the bomb!!!

Sunday, January 8, 2012

Sharp Conversation

After dinner she put down her glass and looked over to me, “How often should I sharpen my knife?”

I looked at her and then over to my wife.  We had just finished dinner and I was sharpening our guest’s pocket knife at the dinner table.  Clearly some sign was needed before I carried on.  I got it.

“If you wait until it’s dull, you’ve waited too long.  It’s always easier to touch up an edge than to bring a dead edge back to life.”  

“What about electric sharpeners?”  She asked a good question and I had half an answer.

“Depends.  Some people press too hard, leave it in contact with the rotating stones too long and heat the blade up too much.  That will damage it.”

There’re really only a few things to remember about tempering and steel.  Tempering is actually a softening step.  The martensite that forms from austenite can make steel so hard as to be unusable.  Tempering allows other softer structures to form and make the steel usable.   Too much tempering, too soft to hold a good edge.  Too hard and the blade snaps too easy.

Almost all the structures that give steel its incredible properties are diffusion based.  Diffusion is driven by time, temperature and moderated by distance.  Heating a knife blade at the thin edge will affect the steel more than heating the spine the same amount.  And the effects of heat cycles are cumulative. 

So how often should you sharpen and how?

I believe you should sharpen when the edge seems to be getting dull.  If you’re butchering a deer you may want to touch the blade up often.  If all you do is cut string and open paper envelopes, you can go a long time.

In the kitchen you should touch up the blade of your chef’s knife before you use it.  The sharpening steel doesn’t sharpen the edge, it draws the wire edge out.  That’s a good thing, as the wire edge is the really the source of sharpness.
You’ll find it easier to keep a sharp knife sharper than resharpen a dull knife.  And I learned that the hard way.

Last summer was a time for “trench warfare.”  I was running underground cable to my soon-to-be-built garage.  After it was up I got a lot of help from my friend Rick with wiring the garage.  With all the cutting and trimming my favorite work knife, a CRKT Crawford Kasper folder, became very dull.

How dull?

So dull it refused to cut anything.

I could have taken it to a professional sharpener and had it re-edged, but as penance and hard luck lesson, I resharpened it myself with my Spyderco sharpener. 

Spyderco Sharpmaker

 I’m still working on it.  I get it sharp, but as soon as I need it for some job it slides toward dull.  I haven’t been able to spend enough time to push it from sharp to very sharp, which is where I prefer my knives.

I also use the Lansky system.  The ability to hold each progressively finer grit stones at the same angle is a gift from the knife gods.   
Lansky system





The downside: it’s a lot of work to set up properly just for a little touch up.

Benchstones. I’ve got more than a few.  The key to good benchstone sharpening is reproducibility and cleanliness.
Gunk up the natural pores in the stone and it will not sharpen.  So use a good oil and clean it off when you’re done.

Holding the knife edge to the same angle through each stroke is critical for a sharp edge.  We can all get better at it, but some people are gifted at it.  I’m not one of them.

Years ago I bought a Buck Honemaster to help me sharpen my knives.  
Buck Honemaster  You can see a dull strip of metal towards the edge sitting on the wood.  That's metal wear from sharpening blades.


 It clamps on your blade and holds it at the angle you select.  The angle isn’t very reproducible between sharpenings, but you can get a fine edge with it.  Of course, as you wear metal from the knife edge, you wear metal from the Honemaster.   It’s a strange sensation knowing you’re destroying the means of making a great edge while you’re making a great edge. 

Buck Honemaster holding my Commando Cutlery on the fine side of a benchstone

On the whole, sharpen your knives before they get dull.  They’ll work better, faster and easier.  A sharp knife reflects well on its owner.