|Ask Dale is a regular column featured in Woodturning Design. Listed below are the questions and Dale's answers from Issue 29.|
|I belong to a woodworking club and have noticed that woodcarvers usually hone their tools after using the wheel to shape or restore an edge, while woodturners usually go from the wheel to the lathe and continue with the turning process without honing. Why the difference in sharpening technique, since they all cut wood?||It is true that carvers and turners all are cutting wood, but the difference is the amount of wood going past the cutting edge at any given amount of time. Years ago, Richard Raffan was turning in my shop and I noticed he went directly to the work from the wheel. I had read that honing makes the tools sharper and was curious why he did not hone his tools, so I asked him. I mentioned that honing tools makes them sharper. He replied, “Honing makes them sharper, but the honed tools will stay sharper for about five seconds. And anyway, sharpening is not my hobby, I am a woodturner.”
Sharper tools are not really the question here, but rather the amount of wood going past the chisel is critical. A carver’s chisel will not remove wood quickly, because it is hand-driven and only a small amount can be removed during the cut. Woodturning is a different problem. The wood is power-driven, so heavier cuts may be made; the wood can be quite soft or very hard, so the amount of wood removed varies greatly. For example, a turner turning an 8" bowl will probably set his lathe speed at around 750 rpm. This is a good, safe speed. Multiply the rim speed by the diameter in inches and this bowl will be turning at 18,850 inches/minute; 1571 feet/ minute; 94,248 feet/ hour; or at 17.85 miles per hour. Compare the amount of wood a carver will cut in the same amount of time, and it is obvious the comparison will favor the woodturner by hundreds of times.
The key to sharpness and edge-holding ability on turning tools is the steel, not whether tools are honed or not. Most turning tools made for woodturning are high-speed steel, tempered to hardness around 63 to 65. Whether a tool is M2, M3, Kryo-treated, powdered metallurgy, or otherwise, it doesn’t make much difference to the average woodturner hobbyist. Practice and experience are of more benefit to the turner, rather than whether or not the tools are hard.
|I’ve read posts and articles about moisture meters for checking dryness of rough turnings, but they are somewhat expensive and I hate to spend the money foolishly. Also, some have pins on the ends that I think would damage the surfaces of the bowls. Are moisture meters really worth buying or are there easier, more accurate ways to determine if a rough-turned bowl is ready to turn?|
Most rough turnings do not require a precise moisture measurement prior to finish-turning, so I do not use a moisture meter to check the dryness of rough-turned bowls. Moisture meters are quite expensive, starting at about $75.00 for a basic one. When roughing out, most bowl turners will leave a rough wall thickness of at least 10% of the diameter, which allows for the finished bowl to be turned to final dimension without getting the piece too thin. After the work is roughed out, there are several options, depending on your experience.
Drying Roughed-Out Bowl Blanks:
Other Treatment Choices:
|I built a steady rest as per one of the articles in this magazine. I used roller scooter wheels from Walmart that look just like roller blade wheels. On most woods they seem to work fine, but I made a large hickory vessel last week, and even though I kept it wet, it still made small check marks that were almost impossible to sand out. Most people would probably not notice them, but I can see where the wheels turned around the piece. Are some wheels better than others, or do you have any ideas about how to keep these marks from appearing?|
|Steady rests for a lathe should be made with “soft wheels,” which will steady the work without leaving marks on the work. Wheel pressure on the work should be minimal. Too much pressure on the work will partially crush the fibers where the wheels run, and the crushed fibers will allow the finish to penetrate differently, at least enough difference to show a line where the wheels have contacted the work. Keeping the work wet probably made the marking problem worse, as the fibers crushed a bit more where the wheels ran and this would show up more when the piece is finished. Next time, use less pressure on the steady rest.|
|I recently started to turn vessels that are about 10" in diameter with a 5" opening. My 4-jawed chuck is too small to span the opening in order for me to reverse the bowl to turn the bottom. I’ve been turning a wooden jam chuck to fit the opening, but I’d like to know if there is a chuck or some other method that I could use that wouldn’t necessitate making a new jam chuck to use with each new vessel.|
|As you have been turning bowls with a 5" opening, there are several options other than jam chucking. However, jam chucking is an inexpensive and effective way to go. You already have a 4-jawed chuck and it’s likely you could purchase a set of auxiliary jaws from your tool supplier. These jaws are available to fit Vicmarc, Oneway, and Nova chucks. Large jaws, such as Cole jaws, will hold work from 4" to 10-1/2" in diameter and Vicmarc Adjusta-jaws will extend from 4-1/2" to 19-1/2".
Another option is to fasten wooden jaws to the chuck jaws to extend the range of sizes your chuck can handle. In the end, jam chucking is the least expensive way to go, but the versatility of the expanding chuck is lost.
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