Popular Woodworking 2000-02 № 113, страница 30
A pro tool may offer a dust cover on its switch (right). Some home tools omit the cover, such as this trigger on a drill (below). However, dust covers are showing up more and more in home tools. most effective, it needs to remain stationary in its housing location (or bearing seat). When you apply heavy loads to a split or two-piece bearing seat, they may flex apart — causing the exterior of the bushing or bearing to slip or spin with the rotating shaft. As this happens, the bearing or bushing is less effective. The worst case is when the slipping or spinning of the bushing or bearing race (the bearing exterior) is excessive. The plastic bearing seats begin to melt, causing the shaft tolerance to alter, leading to major tool failure. Switch Covers Dust, liquids and other debris can enter the switch and cause its contacts to short out, which is one of the first things that usually goes wrong with a tool. To protect against this, some manufacturers place a dust cover or "boot" on the switch. A quality rubber switch dust cover is often designed into the professional-user tool models (and more and more into home tools). You can't always see this difference in the store. More and more professional tools offer an internally sealed switch to keep dust out without impeding access to the switch. Uncovered or unsealed switches are fine for lower-usage tools because of the cleaner work environment and lower frequency of use. Cords Occasional-use tools often use a plastic one-piece molded cord guard, while professional tools use a two-piece rubber cord that has a separate guard. The one-piece plastic cord is acceptable for home use because of the tool's infrequent use (causing less stress on the power cord) and the less extreme temperature demands. A rubber cord on a professional tool allows increased flexibility during normal or cold weather use, while the plastic cord can become stiff and unmanageable, or even crack and break, in cold weather use. The one-piece cord is less expensive because it allows the manufacturer to quickly install the cord during assembly, reducing the overall cost of the tool. Warranties One thing you can check in the store is the warranty offered on a tool. But does a longer warranty mean a better tool? Not always. Professionals notice problems with their tools quickly after the purchase, so a 90-day or six-month warranty on a professional tool is pretty standard. A two-year warranty gives the occasional user the opportunity to use a tool a few times (or for the first time after a year or so) to discover defects. This gives the occasional user a fair shake at being covered by the warranty. In most cases what is more important than the warranty is the manufacturer's reputation for standing behind its tools. Quality manufacturers take a look at warranty requests on an individual basis and usually support their tool unless an obvious abuse has occurred. Brushes Another visible indicator of a high-quality, universal motor tool is the presence of Ball bearings or needle bearings are one indicator of a pro tool. How will you know if your tool has these bearings?You won't unless you take the thing apart. an external hatch that allows you to easily replace the brushes. (Except for cordless tools where external brush access is rare). Professional tools see enough use to require new brushes, so manufacturers make this maintenance procedure easy to do in the field. Tools for the home user don't usually have these hatches because it's unlikely the tool will be used enough during its lifetime to warrant new brushes. Motors A tool's motor is difficult to evaluate in the store. Motors come from many sources and the country of origin isn't always the sign of a good or bad motor. Some motors for power hand tools are rated in horsepower or developed horsepower. Ignore this rating. Check out the amperage rating on the motor's information plate. This indicates how much current the motor pulls from the wall and is a better indication of the tool's power. However, amperage can also be fudged, so the truth is there's no perfect way to compare motors. So Should You Buy a Pro Tool? It's not fair to say that tools for the occasional user are not worth buying. As a matter of fact, if you honestly place your power tool work requirements into the occasional-use category, some can be a good value. On the other hand, if you plan to make a living with your power tools, or if you know you will be using them on a more than occasional basis at home under heavy work conditions, consider buying the professional-user tools. This will keep you out of the repair shops and on the job. pw |
