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.

1 comment:

Anonymous said...

hi, new to the site, thanks.