Your technique / experience in thinning out different blade grinds "thick behind the edge"

T

TC

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Dec 8, 1998
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I currently do not have access to a belt grinder, wheel, or similar power tools. DMT plates of varying grades from 120 to 8000 "mesh" it is.

Working with a flat plane obviously imposes a limitation on the geometry you can work on.

Example from just now: Chris Reeve Nyala Drop Point, hollow ground. ----- I can put a sharp edge on it, but BTE it is still fairly thick, and due to that cutting performance is compromised. To thin the edge out with my flat DMT plates would mean grinding into the saber flat or spine of the blade, which I would prefer to not do.

Aside from, or in addition to, this example, how do you deal with TBE cases? Working parallel instead of perpendicular to the edge is possible but unusual.
 
"Behind the edge" must be the buzz term going around the knife world right now for some reason. The last few days I've been hearing it non-stop.

If I am understanding your problem correctly, it seems like you're going to have to work out some way of sharpening at the edge of the stone so that your spine/flat area of the knife isn't able to contact the stone.

I don't know why you are trying to do this, because if this is really your issue, then it doesn't sound like the knife is intended to have the angle that you are trying to put on it.
 
Thinning is quite common with Japanese kitchen knives and it's generally done using coarse stones (and moving higher in grit). Basically you're just working the flat of the blade on the stone, or in some cases, there's a secondary bevel between the flat and the edge bevel. It's a lengthy process.

For hollow grinds, I think your only real options are to have the blade professionally reground, or else do stepped edge bevels, e.g., if you want 15 dps, go ahead and sharpen at that angle, but then lower your angle to 12° to flatten out the shoulder.
 
I use this approach:

Usually, once the factory edge is dull, I just knock off the shoulders on my Spydercos and microconvex them. So far done it to Maxamet, S110V, Rex45 blades and all ended up an improvement over the factory edge. :thumbsup:
 
I agree with sharpening at the shallowest angle you can, to remove that shoulder, then the final few passes, do t he micro bevel at your preferred edge degree.


I like My bte at .015" or less before I grind my edge on knives that I make .


As a reference, the last Busse type I bought was .065" bte.
WTF!!!
 
For heavy metal removal on stock blades, the baryonyx manticore stone is awesome. I've done many blades with it and it hogs off steel without much worry of going too far too fast like machine grinding.

For harder steels, I still prefer a grinder as the added wear resistance will still take a while, even with the very aggressive manticore stone. Most "too thick" edges are on larger fixed blades using softer metals, so it doesn't come up often that I need to do a heavy reprofile job on higher hardness steels that have a lot of edge length that needs work. Shorter edges are much faster than 6-16" blades.
 
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Crag the Brewer said:
As a reference, the last Busse type I bought was .065" bte.
WTF!!!
Click to expand...
Woh! That's a pry bar!

I'm a sucker for thin-bte blades. Fifteen thou is a good number for EDC knives. The thinnest I've seen from factory (or small shop) was my Oz Rosie which came in at 7.5 thou. I also bought a Spydie Stretch 2 on the Exchange which was reground by the seller to FOUR thousandths ... which might be a little too extreme! 😃
 
Blade Lab said:
Woh! That's a pry bar!

I'm a sucker for thin-bte blades. Fifteen thou is a good number for EDC knives. The thinnest I've seen from factory (or small shop) was my Oz Rosie which came in at 7.5 thou. I also bought a Spydie Stretch 2 on the Exchange which was reground by the seller to FOUR thousandths ... which might be a little too extreme! 😃
Click to expand...
Could you move the side edge of the .004" blade with your finger nail?

That's almost Bur territory. Wow
 
I've got a combo-edged RAT-1 I zero flat-ground on the reverse face and full-hollowed on the obverse thin enough to get it to nail flex. The difference in cutting performance was massive.
 
These are flat ground 1095 (1095CroVan on the KaBar) blades with very thick paint (maybe epoxy) coatings. I didn't measure the thickness behind the edge, but it was stupid thick. Half of it paint!

I put two thicknesses of common masking tape along the spine, and laid the blades flat on 220- and 320-grit sandpaper. The paper was sharp, but that paint is hard as well as thick! It took a few minutes.

QBDWN17.jpg


Two thicknesses of tape gave a smooth transition from the shiny bevels to far enough up the primary grind that the knives would start cutting up to their potential. The 320 left a narrow, smooth surface running the length of the edge. It was a big improvement in cutting performance, I could really feel the difference when performing a few particular tasks.
 
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