Popular Woodworking 2000-02 № 113, страница 29
ferently than a $139 drill. The line blurs again, however, when you start comparing high-end tools to other high-end tools, such as a $140 jigsaw and a $250 jigsaw. Sometimes you don't get what you pay for at that level. Fit and Finish One in-store technique for separating pro tools from home tools is looking at the fit and finish of a tool. Are the seams tight or rough? Do the switches, knobs or levers operate smoothly and with precision? Does the outer surface of the tool have sharp edges? Is the finish or paint bubbled, chipped or uneven? Does the battery slide in and out of the tool easily? Does the router base adjust smoothly? These are things that can help you identify the engineering and care put into a professional quality tool. Fact is most of the differences between tools is internal, and unless you're an engineer with the chance to tear apart a tool, you won't know the difference. Here's a look at some of the internal differences between pro tools and home tools. Bearings and Bushings For the occasional user, manufacturers an- ticipate less wear and tear on the parts, so they use parts rated for a shorter lifespan to keep the price affordable. (Price is a strong selling point for occasional users.) Instead of ball or needle bearings, they'll use bushings or plain bearings to center a rotating shaft in a tool. Bushings provide some wear protection and centering for the tool's rotating shaft. They are usually made from a single piece of metal or nylon, and they have no moving parts. Ball or needle bearings, on the other hand, are made from several pieces of steel, providing high levels of centering accuracy and finer tolerances. Also, ball and needle-type bearings protect the rotating shaft from wear better than a bushing. Ball bearings can handle rotating shafts that thrust as well as spin (called a radial load). Whereas roller or needle bearings are built for handling only radial loads — but they can handle huge loads. Both types of bearings usually cost much more than bushings or plain bearings. Ball and needle bearings are considered almost standard in a professional tool. An instance where this would not hold true would be for the rollers on a belt sander, because the dusty environment would reduce the effectiveness of ball bearings. You're not going to be able to determine what type of bearing or bushing was used in a tool while you're shopping in the store, but the price is usually a good indicator of what's inside. Gears The amount of machining performed on a gear affects the performance and quality of a tool. The tighter the gears, the less play in the mechanism and less wasted energy as the tool operates. Tighter tolerance also reduces wear on the gears, extending the life of the tool. To create a quality gear, you generally have to go through multiple machining steps, with each step adding to the cost of the gear, but it does improve the quality of the gear match. At one time tools for the occasional user could be identified by "straight-cut" or "powdered" gears. Straight-cut refers to Professional tools use gears that are machined several times to a fine tolerance. Home tools might use "straight cut"or "powdered" gears that are inexpensive to make. Though these inexpensive gears are less desirable, their quality has been increasing in recent years with strides in manufacturing technology. a rough-cast gear that is machined in a single step to keep the overall cost of the gear low. A powdered gear is made by pressing powdered steel into a mold under high pressure. This also produced a gear that was less expensive and had a shorter life-span. Today's technology now produces powdered gears that rival machined steel gears for precision. Many manufacturers are now using these improved powdered gears — but not all. In some cases, low-tolerance single-run and the poorer-grade powdered gears can actually be heard as a raspy metal-rubbing-on-metal sound when the tool winds down. Tool Housings When plastic housings on hand tools started to become the norm, they were often considered to be less durable. However, with today's technology, plastic housings are all over the map. Some are still somewhat flimsy. But many quality professional tools now have glass-filled nylon housings that are extremely durable and also insulate against excess heat produced by the motor. Two-piece, "clam-shell" motor or tool housings are found in both professional and occasional-use tools. As the term implies, the whole tool housing is split in half, with a left and a right side. For the manufacturer, the clam-shell tool is easier to assemble at the plant, and any step saved in the manufacturing process reduces the final cost of the tool. As the halves go down the line, the tool components can easily be placed into the open half, and at the end of the assembly process the two halves are screwed together. If there is a weakness of this housing style, it is when your bearing seats also are two pieces. For a bearing or bushing to be DIFFERENCES BETWEEN A PROFESSIONAL TOOL AND A HOME TOOL BUSHINGS AND BEARINGS Pro tools use ball or needle bearings. Some home tools use bushings or plain bearings. gears Pro tools use highly machined gears.Some home tools use straight-cut or powdered gears. housing Some pro tools use a molded one-piece case to support bearings. Some home tools (and pro tools) use a two-piece "clamshell" design. switch Pro tools use a cover on the tool's switch to keep dust out. Some home tools don't have a dust cover. cords Pro tools use a rubber cord that has a separate guard. Home tools tend to have a cord and cord guard molded into one piece. WARRANTY Home tools tend to have a longer warranty than pro tools. brush hatches Pro tools have coin-opened hatches that let you get to the brushes in a universal motor tool. Some home tools do not. |
