Circular VS. Back and Forth?

R

Robert Ptacek

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Oct 8, 2013
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I explored this topic about 5 years ago.I used to grind my relief angle with a circular motion then went to back and forth.I recently tried circular again but after then apexing on a crock stick I noticed tiny microchips.Something I hadn't noticed in years.I do remember someone writing that the crosshatch pattern left from circular grinding can leave fracture points.What do you say,Yea or Nay?
 
I find edge trailing passes are best at avoiding microchipping.
 
Robert Ptacek said:
then went to back and forth
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I don't know except to say if you mean back and forth as say one would do by running a blade back and forth ACROSS a stone so that the scratch pattern is predominately PARALLEL to the edge then that would be a mistake.
I would say MISTAKE with capital letters. Reason being the scratches would in effect be stress risers for the edge, or teeth of a toothy edge, to break off easier.

I hope my weak description makes some kind of visual sense in your mind.

As opposed to the scratch pattern running perpendicular to the edge . . . whether it be edge trailing or edge leading . . . which would be stronger / best case scenario to keep from weakening the edge.
 
What I mean is the relief grind scratch pattern would be more perpendicular to the edge.I've read that the circular strokes leave more overlapping grind marks which also make stress risers.What is your experience?
 
My Grandfather always used the circular motion to sharpen. He was a cabinet maker. My uncle was a meat cutter and he showed
me the push stroke. Which worked better for me. So, I developed that method. I'm not sure if the circular motion creates stress risers. DM
 
I've never worried about a circular grind pattern creating a risk for chipping or other damage. I still think such chipping issues are more about a weakness or fault of the steel itself, sometimes aggravated by the particular choice of stones or other grinding media used to sharpen it. Chipping issues are known to happen with very hard steels sharpened on ceramic rods, for example, which focus pressure via the very narrow contact point. But if one has to worry much about the direction of the scratch pattern on the bevels creating a significant problem, then I'd start thinking about a different steel choice. If a steel chips too easily as a result of sharpening technique, it'll probably chip too easily in use as well.

The one reservation I do have in regard to scratch pattern direction, is with pull-through sharpeners used on softish steels. The entirely lengthwise scratches created there, if they're too deep, can cause a thinly-profiled edge to fold over too easily, which I think is a major reason knives sharpened on such devices often don't exhibit very good edge retention, as the edges created are laterally weaker as a result.

All that being said, I'm still in the habit of always finishing edges with an edge-leading techique, regardless of what technique I used to set the bevels (circular, back & forth, etc). Grind marks perpedicular to or diagonal to the edge make for better cutting in most uses, which I why I do this. If the finishing passes are done to completeness, then the grind pattern left by coarser stages should be erased anyway and rendered essentially moot.
 
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Robert Ptacek said:
What I mean is the relief grind scratch pattern would be more perpendicular to the edge.I've read that the circular strokes leave more overlapping grind marks which also make stress risers.What is your experience?
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These days I'm strictly the former method you mentioned. For almost all of my sharpening I use jigs that leave a scratch pattern fairly perpendicular to the edge and 99% of that is polished edge so the coarse scratches are pretty much gone.

When I was going circular and by hand . . . in the dark, groping and frustrating days of my Palaeolithic (pre jigs and guides) sharpening age . . . it felt like ageS . . . the edges and the steel sucked so bad that any chipping probably would have been an improvement (serration) to my edges.

Once I chucked 'er up into some kind of angle guide (and started using a scratch pattern perpendicular to the edge) the sun rose for the first time on a plane of mud and slimy things with legs and all was right with the world. :cool:

Oh and the edges lasted longer too.
 
John Juranitch, in his excellent and authoritative (IMO) book, The Razor Edge Book of Sharpening, recommends a circular motion to relief grind. I don't have an electron microscope but I'm happy with the edges I get by following his instructions and the great tips I've picked up in this forum.

Obsessed with Edges, thanks, good info! :thumbsup:
 
I have always achieved better results with push strokes. However I think what ever way works for you is the best way.
 
On bench stones, I've usually favored a back & forth scrubbing motion, as an 8" or longer stone suits that method well. The circular grinding method makes the most of smaller stones & pocket hones especially, as their length obviously isn't suited for linear or back & forth strokes.

But no matter which method I use for the heavy grinding, I ALWAYS do the last few finishing passes with an edge-leading technique.
 
I've been using the circular method my whole life, and it seems to work for me. I find that as the blade gets sharper and I lighten up the pressure I get a very fine razor edge that needs very little stropping.
 
My old man is 91. He has a couple old, oily stones that are far from flat and a small pocket stone that almost sheds grit with your thumb nail. He wont let me flatten his stones and he uses the circular motion to great effect.
He carries a leatherman knife in 154cm that has a bit driver that is for heavy stuff and a mini copperlock for fine stuff, they are always quite sharp.
I was taught that way, I have moved on since then, but it will work for sure...
Russ
 
Back and forth to speed up the process to get a burr.

Finish with light touch trailing or leading to clean up.

Which ever you can consistently hit the bevel with.
 
What about this video? Seems to work for him and I have used it on my chisel grinds with good results.
“Side Sharpening with Harrelson Stanley”
 
My father taught me the circular method a long time ago and I was never very good with it. Looking back now I suspect that I wasn't keeping my angle constant using that method. I do much better with edge trailing for the most part, then edge leading for burr removal and final honing.
 
It would have to be pretty coarse stone for the circular pattern to be causing the chipping out OP is seeing.

Normally I only use a circular motion with a puck when doing convex axe/hatchets, finishing with a more perpendicular movement on a fine stone.
In the past I have experimented with circular and it works fine for bevel setting and Ok for final edge work. I still prefer perpendicular or at a rake angle up to 45° when finishing but I don't see it as a big issue. The biggest reason I don't use it is the confused scratch pattern makes it tough for me to tell when the edge is properly deburred.
 
Ace Rimmer said:
My father taught me the circular method a long time ago and I was never very good with it. Looking back now I suspect that I wasn't keeping my angle constant using that method. I do much better with edge trailing for the most part, then edge leading for burr removal and final honing.
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One of my teachers used the “figure 8” pattern to reprofile claiming it removed metal faster. I never went with that. Usually edge leading/trailing if I have good stone contact.

BTW, How are those kippers?
 
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