Wednesday, February 13, 2008

Sharpening Wood Turning Tools (3)

One thing a wood turner must do is rid oneself of the notion that the tool in the shop is a grinder, at least most of the time. For sharpening things like plane irons and chisels we have all sorts of things like sandpaper of various grits, oil or water stones, strops and who knows what all. To each his or her own.

For wood turning tools, we generally go straight from the grinder to the lathe. However, in this case the grinder is the sharpener. It is set up differently from that of a general shop worker or metal worker. Instead, it is set up to work with wood turning tools so as to give them a good edge and get quickly back to work.

For this I like a general purpose grinder available at most hardware stores. Mine is a high speed grinder, 1350 rpm. I realize that some like a slower sharpener but again to each his or her own. The reason stems from older tools make of carbon steel and also from a lack of experience. Improper technique on a fast sharpener tends to build up heat that will destroy the temper of carbon steel tools. Today's high speed steel (HSS) tools will be fine. Good technique makes a world of difference as in almost everything else.

Most grinders come with wheels well suited for grinding, not sharpening. One is likely coarse and the other medium. I like to put the medium one on the right side for grinding away nicks or dents in tools or to shape them when necessary. I do not like the little tables that come on most grinders and made a larger one for mine.

The left side becomes the sharpening side with an 80 grit or 100 grit aluminum oxide wheel. Some people like the white wheels but I find them too easy to wear and prefer a normal consumer wheel which for some reason wears better and costs a lot less.

Keep the wheels clean and round with a wheel dresser. I have used both a diamond dresser and a star wheel dresser and both work well. Clean wheels cut better and cooler.

On the left side goes a jig for sharpening. I simply find it gives a better, more easily repeatable grind. While some people like the jig for eliminating facets on the tool the best reason for using it is the repeatability of the grind. This allows your body to become used to the angles and learn to turn with the same tools, building habits of control. This is especially important for beginners. Once a lot of practice has been made you can more easily compensate for a different grind.

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