Knife Sharpening

[Herman Trivilino]

Knife sharpening has been the Tormek skill I've had to work hardest at.  Using the jig correctly takes practice, and free handing even more so.

Today I was able, for the first time ever, to get that really sharp razor edge I've been dreaming about.  I have an old six inch knife that my grandson bought at a yard sale about 10 years ago for probably $2.  He was just a child and wanted it because it had "Official Bowie Knife" stamped on the blade.  He was allowed to take ownership under the condition that it was to be stored in grandpa's tool drawer and  could be used only under adult supervision.

Today I decided to see how sharp I could get it.  I set the bevel angle as small as I could get it, probably abound 12 degrees (making for an edge angle of 24 degrees).  With the grindstone properly prepared to a smooth-as-glass finish I carefully ground the edge evenly all along one side.  Then I flipped it over and had to grind for a while before I reached the edge.  Again being careful to keep the bevel uniform along the length.  I then polished the bevel on the leather wheel to remove the burr.

I can easily slice quarter-inch wide strips of paper off the edge of a sheet held in midair.  I can also shave the hair on my arm.

I feel like I've reached sharpening heaven.

The key is the small edge angle.  I know the edge won't hold up but still I'm proud.

[grepper]

Way to go Herman!  A rewarding feeling indeed when it's "scary" sharp!

You don't need to have a very small angle, it's easy to do with a 20 degree angle too.  I do it all of the time on kitchen knives.

The trick is to turn the knife often, and be aware of when the burr forms and turn the knife at that point or even before.

I've had some knives that seemed like for some reason I just could not get them sharp.  Ends up they were very hard steel.  When I run into this, I grade the stone to 220 or somewhere in between.  Then do the same thing.  Turn the knife often.  If "somewhere in between" does not work, take it to 220 grit.

Suddenly the knife will get very sharp, but may be somewhat rough.  So then switch to 1000 grit and finish it off.

Some stainless requires a pretty aggressive wheel, and pressure too!

I would hazard an educated guess that is where you have been running into problems on some knives.

I won't even open the can 'o worms about the advantages of a polished or toothy edge. 

[Herman Trivilino]

I know what you mean, grepper, about the hard steel.  When you manage to get a burr, however long it takes and however coarse the grit required, you know you've reached the edge.

I won't even open the can 'o worms about the advantages of a polished or toothy edge. 

The polished edge, along with a small edge angle, is essential for getting that edge that's sharp enough to easily slice through paper.

[grepper]

I'll agree with 1/2 half of that Herman.  A toothy edge tears paper.

But, I've sharpened a machete to 25-30 degrees and it could easily, with little pressure, cut gentle curves in hanging paper.  Cut a 1/16 inch sliver off the side.   It was awesome to hold in your hand.

[Herman Trivilino]

But, I've sharpened a machete to 25-30 degrees and it could easily, with little pressure, cut gentle curves in hanging paper.  Cut a 1/16 inch sliver off the side.   It was awesome to hold in your hand.

Are you talking about an edge angle of 25-30 degrees or a bevel angle of 25-30 degrees (which would be an edge angle of 50-60 degrees)?

[grepper]

I'm talking about a bevel angle.  For example, using the angle tool and setting to it 25 degrees.

[Herman Trivilino]

I'm talking about a bevel angle.  For example, using the angle tool and setting to it 25 degrees.

That's what I figured as that's a nice blunt angle for a machete.  I've got an old machete that I just pulled off the shelf.  I'll see if I can duplicate your feat, grepper.  It needs a new handle, too.

[Rob]

Ive got a machete that desperately needs work....its been neglected for years.  I guess you'd just freehand that right?

[grepper]

It was difficult and time consuming to do.  I used the regular knife jig.  I had to move it up and down the blade which caused variation in the sharpening angle because the blade is narrow (spine to edge) near the handle and much larger near the tip.

But I soldiered on, and eventually a pretty respectable job for a whacking and hacking old garden machete.  Nonetheless you could see variations in the bevel angle in the right lighting.  It was really sharp though.  Much more servicable than the butter knife I started with.

Twer I to do it again, I might try the tool rest just to see if that works better.  I think one of those Chef's Choice or F. Dick diamond wheel sharpeners might make the job much easier and more precise.

It was an interesting project.

[Rob]

how long did it take Mark?

[Rob]

You know I think with blades like a machete...very utilitarian and as you say a hacking tool. Does it really matter if the blade isnt perfectly symmetrical?  Of course you would deliver that kind of result for a chefs knife etc but my feeling is that something like a machete can be free handed without guilt.  The blade will of course look a bit multi faceted...but who cares if its sharp enough to be fit for purpose?

[grepper]

I'm sure I spent hours at it.  For some, in retrospect, idiot reason, I decided I'd put both a new primary and secondary bevel on it.  And... time seems to fly when sharpening.  I think the spinning wheel, and possibly generated electrostatic forces has some effect on the space-time continuum when using the T-7.

I agree.  It's for WACKING and HACKING!  It was for display, or required professional results, I would not do it with the Tormek.

[Rob]

haha....yes....good enough to get the job done but dont worry about the showroom.  Last time I did mine it was on the dry grinder...that must have been ten years ago....I should have a look at that......

[grepper]

Very cool research on knife sharpening, including Tormek results; Or everything you always wanted to know about edges but were afraid to ask:

www.wickededgeusa.com/files/knifeshexps.pdf

[Herman Trivilino]

Ive got a machete that desperately needs work....its been neglected for years.  I guess you'd just freehand that right?

You can use the universal support as a jig.  Keep the back of the blade even with horizontal bar on the universal support.  You could even clamp something to the universal support to act as a stop.