Ku

Kenneth

19/02/2008 10:22 PM

OT (slightly) Sharpening Leather working knives...?


Howdy,

Recently, I have gotten back into some leatherwork after
many years.

Among other tools, I have several "round knives" (the half
moon shaped knives that you may have seen.)

In any case, I had always sharpened them using Japanese
water stones ending with an 8000 grit gold polishing stone.

The edge I could produce was always very good, but...

A few days ago, I got some .3 Micron lapping film, and
worked the wet edge of my largest round knife with it for
perhaps 30 strokes.

Then, I made a cut in some 10 ounce oak tanned leather.

The tool glided through the leather with far greater ease
than I had ever experienced. It was like using a different
tool.

I was truly astounded.

Next, I polished the knife using a strop on which I had some
aluminum oxide abrasive compound, and saw a similar result.
The knife was far sharper than I could achieve using the
8000 stone.

And so these questions:

What might be going on here? Is the grit on the 8000 stone
really so much more coarse that I can feel the difference in
the resulting edge so easily? Or is there something else
happening with the few strokes of the strop or .3 Micron
film?

And finally, would there be ways that I could get these
knives sharper still?

Thanks for any thoughts,
--
Kenneth

If you email... Please remove the "SPAMLESS."


This topic has 4 replies

CF

Chris Friesen

in reply to Kenneth on 19/02/2008 10:22 PM

20/02/2008 1:16 AM

Kenneth wrote:

> What might be going on here? Is the grit on the 8000 stone
> really so much more coarse that I can feel the difference in
> the resulting edge so easily? Or is there something else
> happening with the few strokes of the strop or .3 Micron
> film?
>
> And finally, would there be ways that I could get these
> knives sharper still?

An 8000X stone has particles that are roughly 1 micron in size. Typical
honing/polishing compound is 0.5 micron, and your film is 0.3 micron.

A bare leather strop might get you even further if you're careful.

Chris

dd

"dadiOH"

in reply to Kenneth on 19/02/2008 10:22 PM

20/02/2008 12:42 PM

Kenneth wrote:

> What might be going on here? Is the grit on the 8000 stone
> really so much more coarse that I can feel the difference in
> the resulting edge so easily? Or is there something else
> happening with the few strokes of the strop or .3 Micron
> film?

Coarser. Ever hear of sharpening a straight razor on one? OK, one
can use stones on razors but only to make a new edge if the old one is
really bad. And after the stone comes the strop.


--

dadiOH
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Bl

"Banddad"

in reply to Kenneth on 19/02/2008 10:22 PM

20/02/2008 6:25 AM

Try using a honing compound on that leather strop. Lee Valley sells it. Us
woodcarvers use it all the time and get our knives and carving tools
extremely sharp. The trick is don't use it like barbers sharpen their
straight razors. By that I mean don't slide the knife on one side of the
blade and then on the other, with short wrist turning strokes. (Gee I hope
that made sense!) Slide the knife or what ever along the length of the strop
a few times, in one direction, and then do the other side and repeat until
you are happy with how sharp it is. Good luck!!! I hope this helps.


"Kenneth" <[email protected]> wrote in message
news:[email protected]...
> On Wed, 20 Feb 2008 01:16:44 -0600, Chris Friesen
> <[email protected]> wrote:
>
>>An 8000X stone has particles that are roughly 1 micron in size. Typical
>>honing/polishing compound is 0.5 micron, and your film is 0.3 micron.
>>
>>A bare leather strop might get you even further if you're careful.
>>
>>Chris
>
> Hi Chris,
>
> Please say more about that last thought (particularly the
> word "careful"...
>
> I would have assumed that a bare strop would have abrasive
> characteristics that would make things worse.
>
> Also, I find the film rather inconvenient, but know that I
> can get .3M paste in small quantities. Would using a dab on
> a strop be viable in your opinion?
>
> Sincere thanks,
> --
> Kenneth
>
> If you email... Please remove the "SPAMLESS."

Ku

Kenneth

in reply to Kenneth on 19/02/2008 10:22 PM

20/02/2008 7:05 AM

On Wed, 20 Feb 2008 01:16:44 -0600, Chris Friesen
<[email protected]> wrote:

>An 8000X stone has particles that are roughly 1 micron in size. Typical
>honing/polishing compound is 0.5 micron, and your film is 0.3 micron.
>
>A bare leather strop might get you even further if you're careful.
>
>Chris

Hi Chris,

Please say more about that last thought (particularly the
word "careful"...

I would have assumed that a bare strop would have abrasive
characteristics that would make things worse.

Also, I find the film rather inconvenient, but know that I
can get .3M paste in small quantities. Would using a dab on
a strop be viable in your opinion?

Sincere thanks,
--
Kenneth

If you email... Please remove the "SPAMLESS."


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