Wednesday, June 24, 2009

Knife Project-Sharpening and Restoration

There is a saying that you'll hear around the Bait and Tackle stores, "Most fishing lures are designed to catch fishermen not fish."

The same thing can easily be said about knife sharpeners, gun cleaners, hunting equipment...let's face it guys, we're money targets! :-)

I've sharpened knives for many years. I started like everyone else with a Arkansas stone and oil. When I was stationed in Alaska, we'd spend those long and brutally cold nights working on our Buck 110's.

In time I migrated through the ceramic sticks, diamond stones, leather hones, wet sandpaper etc. Finally I decided to buy a small bench belt sander...and haven't looked back.

Here is what I use:

Here is a description of the belts

A. 15ยต (Micron) Silicon Carbide
These have electrostatically oriented particles (on a mylar backing) that cut quickly, but leave a near mirror finish. The belts become finer in use as the silicon carbide particles are reduced in size through fracturing. Very controllable, they are ideal for carving tools, but are equally usable on straight-edged tools like chisels. 15 micron is the equivalent of 1000x in Japanese water stones.

B. Blue Zirconia
Zirconia belts are a combination of aluminum oxide and zirconium oxide, extremely hard, long lasting, and very resistant to particle dulling. Designed to grind hardened steels of all kinds, including stainless, the 40x is used for major stock removal (e.g., lawn-mower blades), while the 80x and 120x are for hand tool blades.

C. Aluminum Oxide
Our aluminum oxide belts are all semi-open coat with resin-resin bond and X-weight cloth suitable for general sanding.

D. Grinding Belts
Ideal for use with hardened tool steels of all kinds, these belts are especially well suited for knife sharpening. Their bonded coating differs from the slurry coating found on most sheet or belt abrasives. Made by 3M with electrostatically oriented particles bonded to the mylar backing in a heat-set resin, the belts are durable and leave a consistent finish. Depending on the amount of shaping required before final honing, optimal performance and best value are obtained when several successively finer grades are used. The 1200x belt is suitable for final honing in most applications.

E. Leather Honing
Use these lap-joint leather belts on your belt sander to hone chisels, plane blades and carving tools to a mirror finish. In 1" x 30" and 1" x 42" sizes to fit many disc/belt sanders. We recommend our blade honing compound for use with these belts.

Basically here is how it works, you start with a heavier grit belt to profile your edge and work down in grit size until you get to the leather hone belt. I've never had a system where I could get my blades scary sharp anytime I wanted to.

Here is a word of caution. If you work with knives long enough you'll end up with some cuts. There is a difference between scary sharp and just plain ole sharp. Scary sharp will slice you to the bone if you're not careful. It happens to all of us at one time or another.

Here is a recent project that I just finished. The knife is an old one for sure. I would guess that it is at least 50 years old. The blade was corroded and pitted with it's tip broken off at some point. In looking closely at the blade I see that the person got a lot of use out of it and although it shows a lot of wear and tear, there is probably a great deal of sentimental value for it.

I decided to do a good cleaning of the blade, reconstruct the tip, and then give it a sharpening. I also decided NOT to make it scary sharp, just a good clean edge. Here is the project knife next to an old Western knife which is about the same age.

First of all I dulled the blade. It wasn't very sharp to begin with, but I really didn't want any surprises.

This is the blade tip after re profiling it.

I started cleaning it with my Dremel tool and a felt pad with polishing compound. Here we are halfway complete.

And now with the blade cleaned.

To sharpen, you move start with a medium or heavy grit belt. I started here with a medium grit as this blade is Carbon steel and wasn't in need of some serious metal removal. Three or four passes horizontal in both directions and the main section of the blade is complete.

When you move towards the tip, you'll need to slightly tilt the blade up and rotate it away, making a greater angle on the tip than the belly of the blade. If you don't do this, then you'll remove metal from the tip.

Hopefully this image will show the metal wire which is formed as you move through the belts. You know you're on the right track when you regularly make a "wire" on the blade. The final leather strap polish will remove the wire.

Finished, with a mirrored sharp edge.

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