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Stones for grinding and polishing.


GETTING STONED FOR BETTER QUALITY
Cutting or polishing stones can handle a lot of problem jobs in blade finishing. I won't say I discovered it, because using stones to smooth metal dates back a bit farther than I do, and at least one modern maker (Ed Henry ) regularly used stones to refine the metal surface.

First, the coarsest "Carborundum" type stone, made of silicon carbide, can get the grinder marks out of a flat finish, hardened blade faster than rubbing with wet and dry paper and it'll keep the flat parts of a blade a lot closer to a true flat. You'll find them at your local hardware, and they're darn cheap.

Use bench sized stones, that is, about two by eight inches or larger. Small stones rubbed lengthwise can actually cut grooves in the blade and remove far too much material.

For flat finishing, you rub the blade on a firmly anchored stone, not the other way around. Get a new stone and use water or kerosene to keep it from clogging the cutting surface while you work. (Water smells a lot better than kerosene but won't work if the stone has been pre-oiled at the factory.) Used stones have oil in them already, so you'll have to use kerosene with them. Try to get all the coarse stones' scratches running one way so they'll be easier to see when you go on to the next step.

There is simply no better way to get all of the slight ripples from the grinder and grinding belt scratches out of a large, flat ground blade. The coarse stones are self - leveling and far more aggressive than wet and dry paper when kept well lubricated. Maybe a trifle messy, but it works.

After the coarse stone, go on to the medium and fine varieties. The grit varies from brand to brand, but they do about the same work.

Next, finer finishing on flat ground blades can be handled with finer stones. We stock Japanese water stones in 800, 1000, 1200 grits for fast polishing. The stones wear fast and develop a layer of mud as you work. Leave the mud, it cuts faster.

I recommend the Japanese water stones for all tiny knives and particularly for those in or near the miniature class. A 1200 grit finish from a stone is really an attractive satin that can be buffed with very little effort. Grind lines stay much crisper this way! You don't need all of the grits. 800, 1200 and then one of the finest would do the job beautifully. After 1200 grit, buff to a fine finish. Going to a mirror finish on the 6000 or 8000 grit stones is nearly impossible without Japanese polishers' skills.

A little buffing is essential. Even the finest stone, 8,000 grit, leaves some irregularities. What happens is, you polish on a layer of worn stone, loose and floating on top of the solid stone. Each time you press a little differently, you'll break through that layer and rub on the actual surface of the stone. That will make a slight difference in appearance. The finish is still a true 8,000 grit, but the stone leaves a different look to the metal than the mud did.

Finally machinists, Arkansas stone files can be used to shape and finish file work, terminator curves, plunge cuts and folder parts. Most of these have to be used with kerosene, but produce excellent results much faster than with wet and dry paper. A set of Arkansas hard "files" will also do nice job of touch up work on antique, collectors pocket knives.

Do not stone polish an area to be covered by a bolster. Stones will give a smooth finish, but not a particularly consistent or attractive one. You will have to do a final polish of the surface with wet and dry paper or by buffing.

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This web page was created by Zoe Martin
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