Woodturning Design

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Ask Dale is a regular column featured in Woodturning Design. Listed below are the questions and Dale's answers from Issue 5.
I’m new to turning and want to buy some turning tools, but I hesitate to buy things I don’t need–money is tight. Am I better off buying used or should I go out and buy one of the “sets” that I see offered in the different catalogs? What would you suggest as a basic set of starter tools that would help me to make table legs in addition to bowls?
I would not recommend buying used tools unless you are sure the tools are what you need and that they are made of high-speed steel by a reputable toolmaker. I don’t recommend buying boxed sets because many times they include unnecessary tools and don’t include those that you do need. You are better off buying tools suited for your needs. A set of tools for spindle work will vary somewhat from a set of tools for faceplate or bowl work, and the size of the pieces to be turned should be considered when determining what tools to purchase. I would recommend the following tools which are basically the same as those used in the classes I teach: 1/2"-deep fluted bowl gouge which is basically for turning bowls but will function as a roughing gouge on spindle work 1/2" spindle gouge 3/8" spindle gouge 3/4" roughing gouge (for roughing square stacks down to round for spindles) 3/4" radius scraper 1-1/2" radius scraper Diamond parting tool 1/2" rolled-edge skew chisel For more detailed information, refer to specialty catalogs for woodturners.
I see in many catalogs that there are different kinds of steel to choose from, and I don’t understand all the numbers that go with this infor-mation, for instance M2 and A10. Just what do the numbers mean, and how can I tell what’s best for me?
Today’s turning tools are manufactured primarily from two types of steel: high speed (includes M2 and M4) and powdered metal (includes Pro-PM, ASP2030, ASP2060 and A-11). Each type of steel offers particular benefits. While high-speed steel tools can be honed to a razor sharp edge that produces an exceptionally clean cut and smooth surface, they do not hold an edge as long as tools that are made of powdered metal. Powdered-metal tools will hold an edge up to four times longer than high-speed steel tools; however, they will not produce as fine an edge as high-speed steel, resulting in a slightly rougher surface. Many of today’s professionals use powdered-metal tools for rough turning and high-speed tools for making finishing cuts.
I want to purchase a new grinder and keep reading about “slow” and “fast” ones and the different materials and grits for the wheels. I’m confused! Do you have a suggestion?
Slow-speed grinders are popular because they cut slowly and are less likely to produce heat build-up. I prefer a high-speed grinder when fitted with the correct wheel because it will cut quickly. It also isn’t likely to “burn” the edge of the tool if “dressed” periodically using a diamond wheel dresser. The proper wheel and frequent dressing of the wheel is the key to a good sharpening system. As a general rule, harder steel requires a softer wheel. The proper grinding wheel will slowly break down during use exposing a fresh wheel surface that will cut clean and minimize heat build-up. Norton produces two types of wheels made specifically for sharpening high-speed and powdered-metal tools. They are the Type 32A and SG series. I recommend that a grinder set-up for sharpening lathe tools have a 46 or 60 grit on one side and an 80 or 100 grit on the other for “honing” tools. Regardless of the type of wheel you use, get a good quality diamond wheel dresser and dress the wheel frequently to reduce heat build-up.
I’m new to turning and have been doing mainly spindle work when making different pieces of furniture. However, I want to try turning some bowls and don’t understand how I determine the safest speed at which to turn those big heavy blanks. Is there a speed that I can just set my lathe at and forget about it, or do I have to go through some complex formula to determine this?
The selected lathe speed should allow the blanks to be turned with little or no vibration, allowing the tools to produce a clean surface. When vibration occurs, it is usually caused by speeds high enough to cause the unbalanced blank to vibrate the lathe as the piece is trying to fly off the lathe due to centrifugal force and the lathe holding system is keeping the piece in place. The vibration happens because the work is unbalanced in weight. Unbalanced work can be caused by a turning blank not being centered properly on a faceplate or chuck, a square stock not being centered on the drive center, and a revolving center or stock which may be unbalanced due to an area of the blank being heavier than another, usually due to moisture differences in the wood. Another common cause of vibration is turning blanks which are physically unbalanced, such as a natural-edge bowl from logs or burls. Low speeds are needed to reduce the vibration until the work becomes balanced, then speeds can be increased for more efficient turning. Suggested Turning Speeds I have found from experience that appropriate lathe speeds can be determined using a simple formula or equation. This method works for me, and I use it all the time to determine lathe speeds when I begin to set up to turn a piece. D = Diameter of stock in inches RPM = Revolutions per minute of the headstock spindle 6,000-9,000: just numbers used to determine lowest speed or highest speed D" x RPM = 6,000 to 9,000 Example: A bowl blank is 8" in diameter. 8" x 750 = 6,000 8" x 1125 = 9,000 If the lathe is a step-pulley drive system, choose a setting close to 750-1100 RPM–staying closer to the lower number (750 RPM) if you can. If the lathe has a variable speed control system, set it around 750 RPM until the work is turned round, then increase the speed, but I wouldn’t recommend going over 1100-1200 RPM. Several years ago, I visited a friend who had been turning large lamps and platters which he was selling at craft shows. He had retired from the construction industry and was involved in a “useful hobby” at which he was quite successful. He and his wife traveled to shows in their motor home and were enjoying retirement. He was in his shop turning 20" platters glued up from different species of colorful woods. The joinery showed a few heavy glue lines and the occasional small gap, but the quality was good enough for the customer to whom he was selling. I mentioned that 800 RPM was much too fast for platters that size and turning outboard with a light floor stand was dangerous in itself. He felt that neither the lathe speed nor the floor stand was causing any difficulty. His comment was, “I’ve never had any problem.” A few weeks later, one of the platters disintegrated while he was turning it, and he suffered severe head injuries from which he never fully recovered. When I last saw him, he was in a wheelchair, on oxygen, and was watching his shop being sold at a garage sale. This was an accident which never needed to happen. In more than 45 years of teaching mostly woodworking and turning classes, I’ve never seen a smart accident. Now let’s look at the small-diameter works, as there are large numbers of small capacity lathes owned by woodturners. Most will have a maximum swing of 8" and, as noted previously, small bowls of 8" can be safely turned at around 750 RPM if held securely in a chuck or on a faceplate. 6" bowls will require a speed from 1000-1500 RPM 5" bowls or projects require a speed from 1200-1800 RPM. 3" stock from 2,000-3,000 RPM Stock 2" or smaller in diameter usually will be turned at speeds 3,000 RPM or higher, often at the top speed which the lathe will turn. However, caution must be practiced at all times, and if the lathe speed seems too high, slow it down. All the speeds suggested are for stock which is sound, with no defects or checks, and has not been laminated.

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