Best Sharpening Method

[Derek Cohen]

the larger particle are friable, and will either dull or break down into smaller sharper particles. On a soft substrate, the larger particle will bed deeper, lessening the their apparent size difference.

Ahha! Rob, that's why green compound on a solid substratum (I use hardwood, George uses MDF, and you use pine/basswood) gets better the more it is used.

I wonder how this compares with compound on leather?

Regards from Perth

Derek

[george wilson]

That's what I thought,Rob. In any case,I have gotten plenty sharp blades using it in my system.

Derek: Note that Rob said the particles will embed on a softer substrate,making them effectively smaller.

Exactly as I mentioned before,the compound gets finer as it is used. I refrain from adding more compound .

[Rob Lee]

Hi Derek -

I don't use leather personally (Dad did though) ....

Speed and pressure of stroke also has an effect here... too much pressure and the substrate will fold around the bevel, rounding it. Higher speed also makes a given grit apparently finer. So - I look at stropping a razor on leather as a highspeed/low pressure stroke - likely not much rounding at all. Hand sharpening a chisel or plane blade is slower, and can be more pressure, so I don't personally use leather. I know there are all kinds of suitable leathers - I just prefer to use wood, and toss it if worried about possible contamination...

Power stropping - again, different. I do use leather belts, and leather wheels (and hard felt wheels). Whatever substrate holds the compound. (I've seen French razor grinders use paper wheels with SiC grit applied with hide glues....!).

Again - I think the real key is understanding what is happening, so one can chose the method one likes best!

Cheers -

Rob

[george wilson]

Those razor grinders were not so far off of what was done in the 18th. C.. Cutlers used wooden wheels covered with leather embedded with grinding compounds that were naturally available.

[Rob Lee]

Those razor grinders were not so far off of what was done in the 18th. C.. Cutlers used wooden wheels covered with leather embedded with grinding compounds that were naturally available.

Exactly.... an understanding of what was occurring, and technique..... not as specific material focused as we consumers are today!

[george wilson]

They had a pretty large assortment of natural abrasives in the 18th. C.,and some far earlier. Corundum was an excellent abrasive. My FAINT memory says it was mined on Crete,or somewhere in that area. It was superior to the later invented carborundum because it was tougher as well as sharp. Possibly improvements were made in the manufacture of carborundum,as it is the survivor today.

They had "Burr stones",found in America as well as France. The American ones were considered as good as the French. These could be fashioned into grind stones that were pretty effective. I don't know a lot about them.

For VERY fine abrasives,they had diatomaceous earths which had MANY billions of microscopic shells per cubic inch. Still used in some silver polishes today. They had pumice and rottenstone(Tripoli) too.

There are a bunch of other natural abrasives that I won't go into a treatise on. Mostly because I can't recall many of them!

In museums you can run across very old steel instruments and others that were polished to magnificent brightness by those old natural abrasives. And by the skills of those craftsmen who had no modern choices,but got the job done to degrees SELDOM EVER found today. The sharpness of facets,of meeting surfaces was so wonderfully done,it gives me great pleasure and inspiration to see them. I have seen AMAZING drafting sets from hundreds of years ago. They must have cost a small fortune back then.

[Patrick Chase]

They had a pretty large assortment of natural abrasives in the 18th. C.,and some far earlier. Corundum was an excellent abrasive. My FAINT memory says it was mined on Crete,or somewhere in that area. It was superior to the later invented carborundum because it was tougher as well as sharp. Possibly improvements were made in the manufacture of carborundum,as it is the survivor today.

The both survived. "Corundum" is Aluminum-Oxide, "Carborundum" is Silicon Carbide. As you say Al-Oxide (still) resists sharding better than SiC, particularly when it's toughened with Zirconia (ZTA) as in those belts you use :-).

[george wilson]

Silicon carbide was thought to be impossible to produce. That is,to get the silicon atom to fuse with a carbon atom. When the electric arc furnace came along,such high temperatures could be produced that the fusion into SiC was accomplished.

[Patrick Chase]

I used Arkansas stones years ago. I can tell you that they will work fine on MOST steels. But,Arkansas stones are VERY SOFT compared to ceramic stones. I simply could not get my Arkansas stone to fully sharpen a D2 steel knife I had made.

I agree with this. I tried one of my D2 pigstickers on the Norton Ark for kicks and it was slow going with marginal results.

In addition to being hard/slow to sharpen, D2 also has very high carbide content. You ideally want sharpening media that can hone the carbides in-place rather than just erode the metal around them untl they fall out. IIRC ceramic abrasives are softer than chromium carbide, so even they wlll be challenged in that regard. IMO you really want diamond, CBN, or at the very least SiC (in decreasing order of hardness/preference).

[george wilson]

Nope,as I just said,I get D2 razor sharp with my Spyderco ceramic stones. I think the very high chromium content of D2 also makes sharpening and MACHINING (when it is annealed!) pretty difficult.

In addition to a bowie knife I made from D2,I used to use a D2 pocket knife,and sharpened it many times. Now I have FOUND my antique pocket knife(which I lost for a year or 2),with the ball bearing steel blade I made,as the original was too worn down,and find it holds a very sharp edge EL MUCHO longer. That might seem strange,but D2 will get razor sharp,then get just below that sharpness and stay there. D2 was made for shearing other steel,but not made for holding a real fine edge,apparently. Ball bearing steel is a simpler steel with 3% chrome and makes an excellent knife.

[Patrick Chase]

Nope,as I just said,I get D2 razor sharp with my Spyderco ceramic stones. I think the very high chromium content of D2 also makes sharpening and MACHINING (when it is annealed!) pretty difficult.

In addition to a bowie knife I made from D2,I used to use a D2 pocket knife,and sharpened it many times. Now I have FOUND my antique pocket knife(which I lost for a year or 2),with the ball bearing steel blade I made,as the original was too worn down,and find it holds a very sharp edge EL MUCHO longer. That might seem strange,but D2 will get razor sharp,then get just below that sharpness and stay there. D2 was made for shearing other steel,but not made for holding a real fine edge,apparently. Ball bearing steel is a simpler steel with 3% chrome and makes an excellent knife.

What's the old saying? D2 "takes a crappy edge and holds it forever"?

Of course the newer PM variants with fine structure and small carbides change that. I now agree with Kees and others that PM-V11 is likely fairly close to D2 in composition (likely with even higher Cr based on stain resistance).

[Brian Holcombe]

Here's a fun one, I sharpened up a knife I made as a kid to use again as a hatchet, being a supersized Bowie knife it works well. I was obsessed with steel alloys as a kid so I made it in BG-42 and had it heat treated to 62 Rockwell. Chosera stones worked. I might post up a pic if anyone is interested.

[Jim Koepke]

I might post up a pic if anyone is interested.

I always like to look at pictures.

jtk

[dan sherman]

When the electric arc furnace came along,such high temperatures could be produced that the fusion into SiC was accomplished.

When firing a heat they make one hell of a sound. I've witnessed it several times in person, and nothing I've ever heard comes close.

[george wilson]

Probably best NOT to touch one of the electrodes with your TONGUE!!