Popular Woodworking 2003-04 № 133, страница 48
When you're done grinding, J this is what your edge should look like.
area up by the cutting edge. I begin this process with a 1,000-grit Norton waterstone, then do the same operation with the 4,000-grit and then the 8,000-grit stone. The backside should look like a mirror when you're finished.
The Not-so-daily Grind
The next step is to grind the cutting bevel of the tool. You can do this on an electric grinder that has a tool rest, which will produce a slightly curved cutting bevel called a hollow-ground edge. Or you can do it on a coarse sharpening stone, which will produce a flat-ground edge.
Lots has been written about the advantages and disadvantages of each system. In comparing my hollow-ground edges vs. flat-ground edges I personally have found little difference between them in terms of edge durability.
I grind using a diamond stone for three reasons. First, it will never destroy a tool due to overheating (which can happen with electric grinders). Second, I use the diamond stone to flatten the waterstones. And third, the diamond stone is great for touching up my router bits.
I use DMT's extra-coarse stone for grinding my edges (800-666-
4368 or dmtsharp.com). Put the tool in your honing guide and set it so the cutting bevel is dead flat against the stone. Most tools come ground at a 25° bevel, which is good for most woodworking tasks. Mortising chisels should be set for 30°; tools designed for light paring only can be set for 20°.
Don't get too worked up about angles as you begin sharpening. Somewhere in the 25° neighborhood will be fine for most tools.
I use mineral spirits to lubricate my diamond stone. Most people use water, but a sharpening guru at DMT turned me on to mineral spirits. It evaporates slower than water and won't allow rust to build up easily on the stone.
Rub the cutting bevel against the diamond stone and check your progress. You want to grind the entire cutting bevel of the chisel or plane iron all the way across. If you set the tool proper-
When honing narrow chisels, this is the best way I've found to keep things steady and square. Put one finger on the cutting edge; put the other behind the jig to move it.
ly in the jig, this should be about five to 10 minutes of work.
As you progress on this coarse stone, you should make a substantial burr on the backside of the tool. This is called a "wire edge," and you'll want to remove it by rubbing the backside on your finest-grit stone a couple times.
WHY I SWITCHED TO WATERSTONES
There are a lot of sharpening systems out there.And while I haven't tried every one of them, I've tried most. After much experimentation, I settled about five years ago on a system that used DMT diamond stones and oil-
Norton waterstones and the DMT DuoSharp stone are a great combination.The DMT handles the grinding jobs and flattens the Norton waterstones (800-446-1119 or nortonabrasives.com).
stones. My system worked pretty well, but the oilstone part was slow, and my final cutting edge was always "almost" perfect.
Last summer I got my hands on a set of Norton's new American-made waterstones and it was like a door had been opened for me.These things cut wicked fast. And the edge they produce is darn-near perfect.
They feel different than many Japanese waterstones I've used. The best way to describe the difference is that the Norton stones give you different "feedback" as you sharpen. The 4,000-grit Norton actually feels like it is cutting (it is). The 4,000-grit Japanese
Never rub the backside on your coarse stone. That just undoes all your polishing work there.
How you hold the jig is important, too. For plane irons and wide chisels, put a finger on each corner of the tool up near the cutting bevel and use your thumbs to push the jig. For narrower chis-
stones I've used have a more rubbery feel to them in use in my opinion. And they didn't seem to cut as fast at that level. The 8,000-grit Norton waterstone also provides great feedback to the user.
The downside to all waterstones is that they need to be flattened regularly. For this job, I use a DMT DuoSharp stone with the coarse grit on one side and the extra-coarse on the other. I also use this same diamond stone for grinding the cutting edge of all my chisels and plane irons.
The most economical way to get started with this system is to buy a Norton combination water-stone that has 1,000 grit on one side and 4,000 grit on the other. Then buy an 8,000-grit Norton waterstone for polishing. Norton also makes a 220-grit waterstone, but if you buy the DMT diamond stone you won't need it.
— Christopher Schwarz