Sharpening Orthodoxy Overturned?

tuica

tuica

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Greetings...

I have recently gotten back into knives, and also attempting to "hone" my sharpening skills. Discovered two ideas that were counter to my previously held sharpening knowledge.

1) Blademaster Murray Carter claims that you get a sharper edge by "back-stroking" the blade over your stone, rather than the "forward-slicing" motion I have always used.

2) In his book on sharpening knives/axes, etc., John Juranitch says that you will get a sharper edge by using a stone dry - sans oil.


I have not yet tried Juranitch's technique, but did use Carter's method to sharpen the edge of my recently aquired Busse Skinny Ash. It worked quite well.

Both methods (explained in greater detail), are well outlined in these author's respective books.

Am curious how many of you utilize the above methods, and welcome any comments regarding same. Always ready to learn more!

Thanks...and Cheers.
 
tuica said:
Greetings...

I have recently gotten back into knives, and also attempting to "hone" my sharpening skills. Discovered two ideas that were counter to my previously held sharpening knowledge.

1) Blademaster Murray Carter claims that you get a sharper edge by "back-stroking" the blade over your stone, rather than the "forward-slicing" motion I have always used.

2) In his book on sharpening knives/axes, etc., John Juranitch says that you will get a sharper edge by using a stone dry - sans oil.


I have not yet tried Juranitch's technique, but did use Carter's method to sharpen the edge of my recently aquired Busse Skinny Ash. It worked quite well.

Both methods (explained in greater detail), are well outlined in these author's respective books.

Am curious how many of you utilize the above methods, and welcome any comments regarding same. Always ready to learn more!

Thanks...and Cheers.
Click to expand...


In my experience, Murray Carter's back-stroking on a stone only works well on softer stones, like waterstones or jointer stones, or on a strop of some sort. Backhoning on a hard vitreous or natural stone seldom works well, and even on sandpaper is liable to leave small burrs that will need a bit of edge leading or some other method to remove. MC himself has allowed that in the event of stubborn burrs he will resort to a light, edge leading stroke. When used on an appropriate stone, backhoning produces an edge with a really nice blend of characteristics that are hard to come by with other means.

As for using a stone dry, I have, and have gotten good results, but only when doing a very light touch-up. In my experience, any grinding operation produces metal dust and depending on the media, abrasive debris. This will build up on the surface fairly quickly and generally lead to a lot of frustration if not removed somehow, the more often the better. On a vitreous stone, I have noticed this sometimes becoming impacted in the stone surface and effecting the grinding qualities even after it has been washed clean, sometimes requiring the stone to be lapped. In practice I would swear the use of a lube results in a more refined, cleaner edge, maybe not the best type of edge for a follow up burnishing with a smooth steel?

In my experience, use a lube of some sort, and on sandpaper clean it with a brush or eraser as you go. Saves a lot of headaches. You'd have a tough time convincing me I'm better off leaving the debris on the surface of the stone instead of suspending it in oil, mud, windex, etc or removing it outright if possible (sandpaper). Even wiping a vitreous stone with an eraser or brush just doesn't seem to work very well - IMHO. Have no argument with folks that do use their stones dry, but speaking from my experience, is not the best choice.
 
tuica said:
2) In his book on sharpening knives/axes, etc., John Juranitch says that you will get a sharper edge by using a stone dry - sans oil.
..........................Am curious how many of you utilize the above methods, and welcome any comments regarding same.
Click to expand...


This is very effective... IF.... you use the silicon carbide stones that Juranitch sells on his website. I've used them (and his clamp device) for both hard and soft steels and it produces a very nice edge with absolutely no stone loading even after many, many sharpenings. In fact, In the late 70's I wore out one of his coarse stones with never a problem of glazing over. But don't try this with your good quality Japanese waterstones... They will be quickly filled, requiring a full lapping to remove the entire top layer.


Stitchawl
 
HeavyHanded said:
In my experience, use a lube of some sort, and on sandpaper clean it with a brush or eraser as you go. Saves a lot of headaches. You'd have a tough time convincing me I'm better off leaving the debris on the surface of the stone instead of suspending it in oil, mud, windex, etc or removing it outright if possible (sandpaper). Even wiping a vitreous stone with an eraser or brush just doesn't seem to work very well - IMHO. Have no argument with folks that do use their stones dry, but speaking from my experience, is not the best choice.
Click to expand...
I agree. I've used most all my stones dry during past years and noticed they load up quickly. Plus, though meticulous inspection of the edges I've come to realize that a good lubricant during sharpening gives a better final edge. In John Juranitch's book thru careful reading it was that the edges sharpened with oil on the stone didn't last as long pg. 22. Which I wonder about. His book was not meant to be a complete treatise on sharpening as a leather strop is not even mentioned. It was more a compilation of John's findings on sharpening. Much has surfaced on sharpening since 1985. DM
 
Just to throw this out there, as a machinist I almost constantly was running a honing stone over machined surfaces when doing assembly or setup work. I always kept a squirt bottle of mineral spirits handy to lube the surface with and it completely stops the loading of the stones. I find it hard to believe doing any honing but the very lightest finish honing would possibly be better dry.
 
Thanks for your thoughtful replies. Much to ponder...Cheers.
 
I am firmly on the fence regarding edge leading and trailing. When reprofiling it doesn't matter a bit. Back and forth is fine. In fact, gasp, for reprofiling a big knife I often enough pull the blade back and forth lengthwise along the edge to remove metal at a consistant angle of bevel. This works better the straighter the edge...like a BK7 or BK9 or a very nice ham slicer I did...on a blade with a lot of belly, not so much. I know nothing of Japanese water stones other than their fine reputation. I say a YouTube video of one of our members using one and at first I thought he was nuts the way he was doing it...only to learn that one uses those sweeping strokes on water stones. Very interesting. Never tried it. I am a diamond plate man myself.

However, when it comes to the finish, I always use edge leading as, like so many, that's how I learned.

Now wet vs. dry? There I have an opinion. The only thing I use dry is a Sharpmaker and ceramic "steels" or rods. Frankly I'd wet my Sharpmaker too if I had a practical way of doing it.
 
Thanks again for the lengthy and thoughtful replies. I will continue to experiment. I want to be able to obtain a great edge without having to lean on "angle holding devices" or other means.

Some use of this equipment is certainly valid and I hold no disregard on those folks who may use them. Always want to be capable to use/repair nearly anything that I am working on, with a minimum amount of tools/devices. They may not always be there when you need them...Cheers.
 
tuica said:
Thanks again for the lengthy and thoughtful replies. I will continue to experiment. I want to be able to obtain a great edge without having to lean on "angle holding devices" or other means.

Some use of this equipment is certainly valid and I hold no disregard on those folks who may use them. Always want to be capable to use/repair nearly anything that I am working on, with a minimum amount of tools/devices. They may not always be there when you need them...Cheers.
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An excellent goal, experiment as much as possible with many different tools and abrasives.

These are some fantastic links to a body of research that (IMHO) should be required reading for all on the MT&E forum. I routinely post it up with an appeal to be made into a sticky. With Mag's permission, maybe I could just link it to a response on his sticky.

http://bosq.home.xs4all.nl/info 20m/grinding_and_honing_part_1.pdf

http://bosq.home.xs4all.nl/info 20m/grinding_and_honing_part_2.pdf
 
Not trying to hijack the thread by stating this but I too have heard different ways of sharpening are better than others like what has been mentioned here.

Stones dry vs wet, edge forward or back, etc. and now I am trying to get a strop, I am running into the different compounds used (different colors). I see some folks say that the green compound is not good, only use yellow, only use black, only use white....wth?

I would like someone to explain the different strop compounds and why some are better than others. I would also like someone that has experience recommend which color compound should be used for knives and possibly safety razor blades!

Thx.

EDIT: Feel free to PM or email me so this request doesnt take over the thread! :)
 
sir_mike...

As far as I am concerned here, all information to this topic is helpful. I (once) thought that sharpening a blade was a simple operation. But the more I investigated, the more I found...How true!

My recent sharpening experience is to try Murray Carter's (who I just discovered lives about 20 minutes from me), method of "back stropping" on a fairly hard stone and removing the burr by running the edge (using the weight of the knife only - no pressure), through a piece of soft wood. This has put a satisfactorily sharp edge on my Busse Skinny Ash. Give this a try. And keep experimenting. This can't be "Rocket Science!"

Good Luck... and Cheers.
 
It all really depends on what you're trying to achieve with your edge. This is what many people don't seem to understand. The optimal blade prep really depends on the application it will be used for. You want a super-smooth very uniform, narrow edge width for push-cutting and shaving. This equates to very high grit honing and stropping on leather with fine compounds. In this application, the smoother the edge the better. For slicing/sawing cuts, it is beneficial to use lower grits and stropping is a little more optional, or might be done with coarser compounds. In both cases, edges that excel at one type of cutting should not be expected to outperform their opposite counterpart in it's territory. In other words, a super-fine polished and stropped edge will absolutely push-cut better than a coarse-edged knife, but don't expect it to outlast or even outperform a coarser-grit sharpened edge when using slicing/sawing cuts in tougher materials like rope or cardboard. The same goes for the reverse.

In any case, edge-trailing strokes on a blade tend to give rougher finishes and larger burr formation. There is a nice study done by John Verhoeven? (not sure if I've got his name right) that is available on the net in pdf form that shows electron microscope photos of several different edge preps and the differing edge widths and burr formation. IIRC he documents the use of waterstones and ceramic stones on the Tormek, Juranitch's silicon carbide suggestion, the True-Hone system, knife steeling, and both chromium oxide loaded and plain leather stropping.
 
Thanks for the detailed info, Kretz. Think I am looking for the slicing/sawing edge, with longer lasting capability...Cheers.
 
tuica said:
Thanks for the detailed info, Kretz. Think I am looking for the slicing/sawing edge, with longer lasting capability...Cheers.
Click to expand...

This topic comes up fairly often. This is a recent thread where I was able to post some micrographs showing coarse medium and fine coming off my sharpening widget, along with a few impressions at each stage. Sometimes just being able to see what the edge really looks like is enough to clear up the thought process somewhat.

http://www.bladeforums.com/forums/s...th-edge-aggression!?highlight=edge+aggression

Might as well throw in another sharpening orthodoxy overturned, but within narrow parameters - that of only being able to strop with very light pressure. On my WB I routinely use several times the amount of pressure I use when grinding on a stone or sandpaper, this with compound on paper, and especially when burnishing on plain paper. Way more than can be safely used on a regular strop, or when backhoning on a waterstone. I found that stropping on hardwood with a slurry of compound and oil likewise allowed a much greater range of pressure, but was very fussy re how thick/thin the slurry was. Also the texture of the hardwood played a role - klugy but effective..
 
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