Woodworker's Journal 2008-32-2, страница 30
"Some chucks are excellent Some are more useful as paperweights than for their intended purpose." — Betty Scarpino Some chucks are excellent. Some are more useful as paperweights than for their intended purpose. You can figure out which one you like best by trying out a friend's or by taking a class where chucks are used. Hey, if you don't mind the expense, order several and decide which is best for use on your lathe and which works best as a paperweight! Personally, I find that chucks are excellent for roughing out and returning green bowls. They're also useful for spindle turning, especially when turning boxes and production items. There are large- and small-capacity chucks. Select accordingly. Occasionally clean and check the jaws for wear and tear. Those jaws do loosen over time, and that slippage can cause problems. Additionally, (again) please keep the speed of your lathe reasonable — chucks aren't designed for 100 percent secure holding, especially with large-diameter bowls. Drive and Live Centers Recently, a student sent me a message asking why the piece of wood he'd attached to the lathe between centers wouldn't stop spinning when he was trying to make a cut, no matter how much he tightened the tailstock. After a series of messages back and forth, I finally figured out the problem. He was using a live center in the headstock instead of a drive center. A drive center directs a lathe's power to spin the wood. They are inserted into the spindle of the head-stock and have two purposes: 1) they hold the wood onto the lathe, and 2) they grip the end of the wood so that the lathe's power can turn it. For turning between centers, it's useful to use a live center in the tail-stock (instead of the old-fashioned dead centers). Live centers rotate because they are equipped with bearings. This is nifty because it allows the center to rotate as the wood spins, thus preventing the wood from burning, yet still holding it onto the lathe. With the now widespread use of live centers for the tailstock, manufacturers turned their attention to centers for the headstock: what could be invented that would not only be useful but generate sales? I'd have to say that the spur drive center is on its way out — safety drive centers are the current favored gadget. The problem: some of these new drive centers look a lot like the live centers. It's confusing for beginners! And confusing for most woodworking stores. They are not yet savvy about the new safety drive centers. When my student went into his local woodworking store to ask for a drive center and came home with a live center, the mistake was understandable: drive/live; center/center; tail-stock/headstock. Spur drive centers are certainly all right to use, but understand that they hold the wood so securely that when a catch happens, the "give" could be the tool instead of the wood. Safety drive centers also hold the wood securely (and rotate the wood properly), but they will allow for the wood to release its spinning motion when a catch happens. They also teach students to use a more controlled cut while keeping them out of trouble. Skill Versus Technique If what you are doing while turning isn't working well, step back and analyze the situation. Perhaps the solution isn't that you aren't skilled enough. It could simply be that you are misapplying a technique or using the wrong tool. Be safe and have fun turning! J* Betty Scarpino lives and turns in Indianapolis. She is a regular contributor to the Journal and teaches and demonstrates throughout the U.S. Old School New School \Use i: ■ headstock Use in headstock Use in tailstock 30 April 2008 Woodworker's Journal |
