Maximize edge retention

[Sharpco]

What people want most about kitchen knives is edge retention. What do you think is a way to achieve this using Tormek?

There are two cases here.

1. Management by honing steel
2. Use without management

I'm sharpening to 30 degrees (15 + 15) with Tormek, but I couldn't hear that edge retention is good. Should I lower the angle?

[Ken S]

Good question.

I removed the usual steel with file cuts from my knife block and replaced it with a ceramic "steel". The ceramis steel has triangles built into the handle to set the bevel angle properly when using it. It works very sell. It was a gift from Steve Bottorff. Steve told me that he purchases them from Smoky Mountain Knife Works. According to Steve, they are inexpensive, with shipping costs comprising most of the cost. Steve purchases them in quantity and often gives them to customers.

If you bought them in quantity, you could carry a boxful in your van and sell them (or give them to regular customers). Although inexpensive, they are a quality product. They both look nice and work well. They are easily cleaned with scotch brite and soft scrub.

Ken

[Sharpco]

You're right Ken.

I also believe that some abrasive material is better for managing the knife than regular honing steel.

But I think there is something wrong with the fact that the sharpness of the knife I sharpened with Tormek can only be maintained for a few days.

[cbwx34]

Most kitchen knives are made of comparatively "soft" steel, and typically require some type of edge maintenance between sharpenings.  The use of a ceramic is a good idea... it's what I use, and recommend also.  But even a regular "honing steel" will do the job.  The trick is proper use.

Most use a honing steel "as seen on TV"... multiple rapid swipes at improper angles.... looks cool right?  But this is detrimental to the edge.  A couple of carefully controlled alternating swipes, similar to how you'd use the ceramic, will do a lot to restore the edge... especially if the steel has the little grooves cut into it.  John Juranitch in his book "The Razor Edge Book of Sharpening" outlines this in detail.  I highly recommend this book, regardless of how you sharpen.

A couple of more points about steels... the steel must be harder than the knife.  If you're buying high end "modern" knives with HRCs in the 60s... the typical steel that comes in a standard knife block may be too "soft" to correctly do the job.  Also, whether a steel or ceramic is used, try and teach the customer to feel for a "rolled edge", and have them start on that side.  (Not critical, but it does help).  And try and get them to hone at or slightly higher than the sharpening angle with light pressure, and not the crazy way I mentioned earlier.

As for the edges failing after only a "few days"... I'll preface this with more information is needed.... what type of knives, how are they used, etc., to properly solve the problem.   But, typically, a knife that quickly fails early is the result of a burr or wire edge that isn't properly removed.  Try testing your knives after sharpening by slicing thru some thin cardboard or even regular copy type paper a few times... if the knife makes 2-3 "clean" cuts, then starts to make "ragged" cuts, or even starts tearing the paper, you have a burr/wire edge issue you need to address.  I would test a knife on copy paper when I first learned to sharpen, and thought that if it quickly failed, it was "cheap steel"... took me a while to learn proper burr/wire edge removal.  Just because it feels and acts sharps may be deceiving.

Hope that helps. 

[Ken S]

Good post, CB.

Ken

[Sharpco]

Thank you cbwx34.

I will try to remove the burr completely to resolve the knife dying quickly.

[grepper]

As mentioned in the previous posts, what causes a blade to dull is rolling of the edge.  Sometimes it's bad enough to actually feel with a fingernail.  I know, you could whack the edge on something hard and actually bash it in, but that's not what I'm talking about. 

I took a knife and put a highly polished, mirror bevel edge on it.  It was very sharp, measuring 120, 130 and 125 gf with the PT50B sharpness tester.  It melted through tomato skin effortlessly.  Then I cut a bunch or cardboard with the knife.  No impact, just slicing cardboard.

See first attachment.

After cutting the cardboard, sharpness readings were 270, 240, 315.  Much less sharp.  The blade just slid back and forth, riding on the surface of tomato skin.   The thin, very sharp edge had rolled, forming a dull rounded tube on the edge. 

See second attachment.

So after the edge has rolled, there are two things that can be done.  One is to simply straighten, or un-bend the rolled edge by dragging it over a hard smooth surface.  The other is to apply an abrasive to the edge such as a ceramic rod or other abrasive material.  That would probably straighten the edge as well as abrading some of the steel away.  Sort of micro-sharpening.

Obviously softer steel will roll more easily than harder steel.  But harder steel is more difficult to sharpen and can be prone to chipping.  Harder steel is more difficult to straighten when the edge is rolled, and will tend to fracture more quickly than softer more malleable steel after repeated un-bending of a rolled edge.

I guess it depends on how the knife is going to be used in order to find that perfect blade for a particular task. 

[Sharpco]

grepper.

After reading your post, I felt I needed a microscope to see what was happening on my edge. Thank you for your help.