69 - Bench Top Storage System, страница 33
QUESTIONS & ANSWERS
fussier than others when it comes to ■ the quality of the castings. Poorer-quality castings may have voids or rough spots where the iron didn't completely fill in the mold. Instead of rejecting these castings, some manufacturers merely fill in the voids and paint over them. If you see evidence of this on a tool that you are considering for purchase, it could be an indication of poor quality control.
Another important step in the making of cast iron machinery is the "seasoning" of the castings. After the iron cools, the casting is removed from the mold and left to sit outside for several months to "age." This step is important since it allows the cast iron to move and settle before it is machined so that it will be less likely to warp later.
Unfortunately, it's impossible to look at a table saw in a showroom and tell if the castings were seasoned before being machined. But one thing you can do is examine the thickness of the castings. Better equipment will have thick-walled castings with plenty of ribbing and
cross supports. This results in greater strength and an improved ability to dampen vibrations.
Meehanite - A couple of tool manufacturers (Powermatic and General) tout the fact that they use "Meehanite" cast iron in some of their higher-end power tools. Meehanite cast iron is made using a patented process that results in a dense, fine-grain structure that is superior to ordinary cast iron. It's more costly to produce, but is less likely to warp or twist over time.
Disadvantages - Of course, as good as cast iron is for woodworking tools, it's not perfect. The weight factor is great for dampening vibrations, but not so good if you have to move your tools around a lot (which is why you don't find much cast iron on portable power tools).
Cast iron also tends to rust fairly easily, so it requires regular maintenance to keep it in pristine condition. (See the box on this page for more information on this.)
Because cast iron is a relatively soft metal, it can be scratched and
dented if you're not careful. And cast iron is also somewhat brittle. A misplaced blow from a hammer can easily crack or break a cast iron tool.
Despite these drawbacks, manufacturers haven't come up with a better substitute for cast iron. Where woodworking equipment is concerned, cast iron is still king. &
Automated equipment is used to machine the upper arm castings for Delta's 14" band saw.
Dealing with Rust
Rust is the chief enemy of cast iron. But with just a little maintenance, you can keep the cast iron surfaces of your tools looking as good as they did when new.
The best way to deal with rust is to prevent it from forming in the first place. To do this, I turn to a simple but effective solution — paste floor wax. Every week or so, I rub a coat of wax onto all the cast iron surfaces of the tools in my shop. The wax not only protects against rust, but it helps your workpiece to slide over the surface of the tool a lot easier.
You can usually find paste floor wax in the cleaning products section of your local supermarket. (Note: Avoid using car waxes on your power tools. These may contain silicones that can rub off on
the wood and interfere with the finish on your completed project.)
Sooner or later, you'll probably encounter some rust on your tools. But unless the rust is severe, it's really nothing to get alarmed about Light rust can be removed with steel wool or synthetic abrasive pads (like ScotchBrite pads). Recendy, I've been using Sandflex blocks to remove rust (see photo
on left). These rubber-like blocks are embedded throughout with abrasive particles. They remove the rust like a giant eraser. (See page 35 for sources.)
Once you've taken care of the rust, just apply the paste wax as usual. Or if you prefer, you can use a spray-on rust inhibitor like TopCote or Boesliield (see photo on right and page 35 for sources).