Showing posts with label grinder. Show all posts
Showing posts with label grinder. Show all posts

Thursday, June 23, 2011

Five Tips for Sharpening Your Wood Turning Tools


One of the first things that woodturners realize, especially if they come to woodturning from other types of woodworking, is turning tools need to be sharpened early and often. In most cases they need to be sharpened a lot more often than other cutting tools and the skills needed are different than those to sharpen most other tools. Here are five tips to help get sharp tools quickly and easily for the wood lathe.
First of all there is the need to recognize a couple of angles, thirty and forty five degrees. Almost all cutting woodturning tools will use these angles and the few that do not will be glaringly obvious. Gouges and skews cut wood. Roughing gouges and bowl gouges are generally sharpened to forty five degrees and straight across. Many woodturners start with spindle turning and spindle gouges are sharpened at thirty degrees. Some turners try to sharpen roughing and bowl gouges to that same thirty with terrible results and are amazed when someone shows them the magic of forty-five.
Second is the need to keep things simple, especially at first. Stick to what has worked for centuries. Woodturning is over three thousand years old and most of what is done is tried and true. This is not to say that there have not been changes but it is good to start with the established norms before branching out. For instance, there is the other typically used grind for a bowl gouge that has long wings and a bevel that alters from about forty five at the edges to seventy in the center. A straight forty-five works beautifully and is a lot easier to do at first.
Then there is the sharpening of scrapers which are the real exception to what appears to be a sharp edge. They are sharpened almost square at about seventy to eighty degrees and the burr that is raised is the cutting area. It is quickly broken away and resharpening is needed often.
This brings up the fourth tip and that is to be satisfied with an edge that is sharp enough to remove wood and still hold up to the punishment of woodturning. For this a grinder is the best tool to use as a sharpening station. Equip it with an eighty grit aluminum oxide wheel and ignore the usual whet stones and honing strops. It can take a lot of time to get a razor edge that will disappear in the first second of turning.
Fourth, use a jig. Freehand sharpening is an art and craft in its own right and it is easier to learn to turn with sharp tools from a jig rather than trying to learn both crafts at once. Jigs will also teach the movements that are needed for freehand turning if the need arises. They can be either cheaply made in the home shop or purchased from just about any woodturning supplier.
Fifth and perhaps most important is to relax and take it easy in the sharpening. It is a part of the turning process and meant to be enjoyed. If an edge comes out wrong it is a simple matter to try again. A little time, a little attention and a little steel and back to the wood again.
Sharpening is not hard and woodturners have been getting a sufficient edge for over three thousand years. With a little practice you will be joining the group and the shavings will fly from a good, sharp edge.

Thursday, February 17, 2011

Sharpening Woodturning Tools: Making Sense Of Grinder Wheels For Sharp Wood Lathe Tools


Getting a good edge on a wood lathe tool is one of the great difficulties for a beginning woodturner and an ongoing concern for intermediates and experts. While the grinder is the tool of choice for woodworkers sharpening tools for wood lathes, getting it set up with the correct wheels can be a confusing challenge. It need not be with a couple of simple steps.

First it is necessary to move in thinking of the grinder as a sharpener. Many people come to woodturning from general woodworking where the grinder is used to remove lots of metal in a hurry so as to grind away nicks and breaks in chisels, plane irons and the like. Water stones and honing implements are used for final edges. Woodturners move from the grinder to the wood. Most shop grinders are not set up for this and the problem is largely the wheels.

Thus the second consideration is to replace the grinder wheels. While it is agreed that since woodturners generally use high speed steel tools they should have aluminium oxide wheels, there is a lot of confusion in the catalogues as to what color wheel to get and what bond to have. The color reflects individual manufacturers attempts to make choosing between grades of their particular wheels and has little to do with other wheels on the market. Consideration then should be given to grit and bond.

The bond of a wheel refers to how friable the material is that holds the aluminium oxide together. More friable bonds allow the material to break away quickly thus leaving a sharp cutting and cooler grinding surface. Unfortunately, the most friable bonds manufacturers recommend for woodturners groove, pit and wear quickly requiring a lot of wheel dressing and expensive replacement. Thankfully, almost any aluminium oxide wheel generally available to the home market is sufficiently friable for good sharpening with good wear so making sense of the friable numbers of bonds is not necessary. Just get a good wheel.

Third is consideration of the grit. While it may encourage argument, a good setup is a fast cutting wheel of about 46 grit on one side of the grinder and a sharpening wheel of eighty to one hundred on the other. With a good jig especially, this will meet all the shaping and sharpening needs of the woodturning shop.

Simply put, a couple of inexpensive aluminium oxide wheels of appropriate grit will give a lot of sharpening satisfaction and help to make a lot of shavings for a long time to come. Keep it simple and keep it fun.