[Sharpening-jig] Slanted grinding stone.

[Bill Wheaton]

Brent
Have you thought about raising the far end of the Norton corborundom
stone by 2 degrees instead of making it coplanar with the glass?

That way, the heal of the bevel will be worn more and cause it to
curve and merge evenly into the micro bevel angle (which would still
be done the same way).

Also, I have drawn up a version of your jig in sketchup which is
contained in a self contained box for clean storage to keep dust out.
I'd like to upload it to the Sketchup 3d Warehouse for others to use
and learn from. Is that ok with you?

-Bill Wheaton
Decatur, GA

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[Brent Beach]

Hi Bill

On tilting the stone - not a good idea. For those who have not thought
about this, a non-planar stone creates a rounded bevel. To see this,
imagine the jig as far from the stone a possible, with the blade just on
the stone. The jig is set for 25 degrees say and the stone slopes up 2
degrees. At this point the stone is trying to put a 27 degree bevel on
the tool. Now, with the jig as close to the stone as possible and the
tool edge well along the stone, the angle is again 25 degrees (the jig
is almost in the plane of the stone). As the distance of the jig base
move from its nearest position to its farthest position, the angle
varies from the smallest to the largest (from the angle with a planar
stone to that angle plus the stone angle).

You should not get closer than 4 degrees between the primary and first
honing bevel angle. If the angle is smaller, the first honed bevel gets
wide too fast. A wide bevel takes longer to hone - unnecessarily long.
So, no point in curving the primary into the first secondary. If you set
the grind for 23 and curve into 25, you are going to have a wider
primary than necessary - more work.

No problem on adding a sketchup model to the 3d warehouse - I might even
learn something. I have a number of jigs of different sizes for
different uses, and just put them all into a plastic tool box with my
other sharpening supplies. They may get a little dusty (and oily and
grimy) - I think it of patina.

Brent

On 19/04/2010 8:09 PM, Bill Wheaton wrote:
> Brent
> Have you thought about raising the far end of the Norton corborundom
> stone by 2 degrees instead of making it coplanar with the glass?
>
> That way, the heal of the bevel will be worn more and cause it to
> curve and merge evenly into the micro bevel angle (which would still
> be done the same way).
>
> Also, I have drawn up a version of your jig in sketchup which is
> contained in a self contained box for clean storage to keep dust out.
> I'd like to upload it to the Sketchup 3d Warehouse for others to use
> and learn from. Is that ok with you?
>
> -Bill Wheaton
> Decatur, GA
>

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Victoria, B.C., Canada