Progressive Stropping---Using an ERU Sharpener.

Fred.Rowe

Fred.Rowe

Knifemaker / Craftsman / Service Provider
Joined
May 2, 2004
Messages
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I have been working on this tool for almost 4 years; refining the machining process and making slight changes to the tool itself. The truth is, I am still learning about how to use it and how to get the most out of it.

My initial thinking was: Make a sharpener with identical opposing disc that support two perfectly aligned [mirror imaged] carbide surfaces that can be adjusted in precise increments of 1 degree or less. When I say perfectly aligned surfaces, I mean they are just that. The carbides are lapped on a diamond plate "after" they are epoxied in place. The end result, is a perfect "V: Hurrah!! Now that I have accomplished this; what are its uses?



What I wanted to share on this thread is something I have just discovered over the last 6 months or so. I call it "Progressive Stropping".

It goes like this: sharpen the blade on a stone or diamond plate using degree wedges to control the angle and produce a "flat" cutting edge or use a sharpening system with a known controlled angle.
Take the edge to where it has a small burr from plunge to tip.
Using a matching inclusive angle set on the ERU remove the wire edge by pulling the blade through the "perfect V" You will feel the burr come off.

An example: say you sharpened the edge @ 30 degrees inclusive. After the burr has been removed using a matching angle of 30 degrees;
widen the "V" by approximately 2 degrees to 32 degrees and pull the edge through the"V" keeping the blade aligned with the alignment pin.
It only takes one to three passes at this setting. Now widen the "V" again to 38 to 40 degrees and pull the edge through the "V" keeping the blade aligned using the alignment pin. The passes that are made at 32 and 40 degrees are stropping the edge along slightly different areas of the edge. The last passes at 40 degrees is only touching the apex itself.

I have found I get a much more refined edge stropping in this manner than I do using a normal strop where just one side is stropped at a time.

This is for you folks who have one of my sharpeners and have yet to discover this technique. I use this whenever I touch up my kitchen knives, my EDC or any other knife that has been ground with a known angle, cutting edge.

Try this and let me know what you think. As someone who has been learning how to use this tool for a few years, I believe this to be the ultimate in Stropping.

I have not been on the forums much of late. We have been upgrading the shop and we have been swamped trying to stay ahead. At 72 I don't put in the 12 hour days anymore but I get just as tired in 6 hours :)

Regards, Fred
 
You are creating a convex edge that is very similar to the way a katana is sharpened. It is an assembly of minute flats that create a curved edge. This is a very strong and sharp edge.
 
You created this with your bubble jig , as Stacy is saying . Do you remember , several years ago , you and Rick Marchant ( maybe wrong last name ) from Canada , when you started with your bubble jig . He did a wip , with several flat ground steps all the way up the blade and measured , supporting the use of your jig to complete a strong flat/ convex ground blade .

Well , any way that is how I remember it , and have been using the technique to great success .
 
ONeill said:
You created this with your bubble jig , as Stacy is saying . Do you remember , several years ago , you and Rick Marchant ( maybe wrong last name ) from Canada , when you started with your bubble jig . He did a wip , with several flat ground steps all the way up the blade and measured , supporting the use of your jig to complete a strong flat/ convex ground blade .
e
Well , any way that is how I remember it , and have been using the technique to great success .
Click to expand...

If I remember correctly we called it a faceted edge.

What I am talking about here is not really different surfaces along the cutting edge but rather, the angle at which the abrading material contacts the edge. The same to a very minute degree; but with only one or two passes I don't believe there is any appreciable change in the edge.
Using this technique over the last 6 months or so I believe what takes place is: when the wire edge is removed and the same angle is maintained in the "V" until the edge "feels" smooth as it passes through the "V" [ not every area along the edge is being contacted on a microscopic level, part of the surface area of the edge is being passed over] When the angle is increased and the edge is drawn through the "V" more of the surface closer to the apex is contacted, smoothing this area. Then when the angle is opened to the 40 degree angle, just the sides of the apex are contacted which makes the edge more refined, removing or straightening the sides of the apex.
What impresses me about this is I get much sharper edges using this technique on knives I have sharpened using the ERU for several years.

I need to have some micro photos done as the technique is being performed.

Fred
 
My take is that the micro-steps are creating a much firmer edge. Technically, the apex is ten degrees higher than the overall 32 degree edge angle, but this is on such a tiny scale that there is no real difference.

First, the ERU will cut the wire off cleanly. Normally it just breaks off and leaves a micro-serrated edge. This "feels" very sharp, but is not as sharp as a precise polished edge. Just buffing the wire off does not create a polished edge, .... it creates a polished microscopic saw blade. Nothing wrong with that, and done right ,it will be scary sharp. The folks who strop and polish their edges by hand up to 50,000 or even 100,000 grit can eliminate this, but the cost, time, and effort needed is a lot just to get a good edge to become a super edge. Any slip or change in the sharpening angle can ruin all your hard work.

Fred's procedure eliminated this polished serrated edge without an hour of sharpening and edge polishing.
With the ERU set at 32 degrees, after a few strokes over the 30 degree sharpened angle, the wire is cut away - leaving the last .003-.005" of the edge a perfect 32 degree "V". Switching to 42 degrees will only cut on the last .0001" of the edge. This will cut the apex to a very precise and microscopic "V". Because the amount of contact area is so minute, a few strokes will do the entire edge. Additionally, as the very precise carbide edge guides compress and strop the apex at the higher angle, the apex will become very smooth, and possibly hardened to a higher degree due to burnishing. The will create a low friction and more robust edge. I suspect it will last longer than a normal 32 degree edge and cut better.

I have a wakizashi that I am finishing which would normally get a convex edge. I plan on taking my ERU and seeing how the micro-faceted edge comes out. I expect good things.
 
Stacy,

Your explanation is far better than the OP. I need to get with you before I post.

Thanks Stacy!
 
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