Scienceofsharp - what honing and stropping really does

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C_Claycomb

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Oct 6, 2003
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A recent thread about strop boards and strop hardness got me thinking about the differences between stropping, lapping and honing and whether there were any objective characteristics that would help to define and describe where one might end and another begin. This brought me to :

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https://scienceofsharp.com/home/

This may well have been posted here in the past, but I cannot find mention of it using search, so worth posting. He has excellent scanning electron microscope (SEM) photos of the cutting edges that result from various sharpening methods, including stropping. Much of the emphasis is on razors, so low angle edges in steel that must hold a fine edge, not the high tech carbide loaded steels that excel at rope cutting, but are not so good on wood. Well worth a look.

I particularly liked
 
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punkrockcaveman

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Jan 28, 2017
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Quality reading. So to get this straight, it's better to do 10 laps with leather and a fairly abrasive compound, then 10 laps with clean leather (or with very fine compound), then it is to do 100 laps or more with a leather and a fine abrasive?

As in introducing a quick heavily abrasive stropping coupled with a quick fine stopping is better than flogging away with a singular strop?
 

Robson Valley

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Nov 24, 2014
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McBride, BC
When you rub any steel tool edge across a scribble of CrOx/AlOx (or either, plain), you see a tell-tale black streak of finely divided metal particles. You have seen the same as silver in a black & white photographic negative.

Consider the time it takes, the number of strokes, to arrive at a sharp edge.
Get down there quickly with coarse abrasives to shape the basic edge then smooth out the big scratches and refine the edge with progressively finer abrasives. Clearly quicker than 500 passes over a fine abrasive.

Farrier's crooked hoof trimming knives are commonly sharpened at 25 degrees (total included bevel angle.) Most good wood carving gouges are 20. Most good wood carving knives are 12, no more than 15 degrees. I use other angles for other wood carving tools.

So the bevel on the farrier's knife needs some cutting back to be useful for wood carving. I do that with a simple angle guide and a chain saw file to rip it down to somewhere between 12 and 15 degrees. Then I use 600, 800, 1000, 1200, 1500 grit papers. I use black felt marker and a 10X magnifier under a bright LED light to monitor progress.
That's about 3 micron grit nominal particle size according to 3M, the manufacturer. Last will be a rub with the honing compound, a test in the carving wood of the day and back to it.

The two pages of SEM pictures which convinced me of what I needed to be doing and what was mythology were published in 1995.
After nearly a decade of doing this, I think it's quick, effective and economical. You might not find it so.
 
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