Creative Woodworks & Crafts-050-1998-winter, страница 64

Scroll World Bonus!

By Ron King

1SH

Material Thickness Blade

Note: where a Standard blade is specified, Reversed tooth or Double tooth may be substituted.

Bone varies considerably in density. Blade selection must be determined by trial and error, but usually standard blades will perform well.

Corian is much denser than most plastics commonly cut on scroll saws. Heavy paper glued to both the top and bottom helps, but using a blade lubricant such as wax or oil works best.

Leather cuts beautifully on a scroll saw. The only difficulty is bottom support because of the opening in scroll saw tables where the blade is located. Use an overlay table or cardboard on the underside.

Hard metals, such as some stainless steels, nickel alloys, and tool and die steels, are so hard that it is not practical to cut them with a scroll saw. However, many of the regular mild steels can be cut using a cutting fluid to lubricate and cool the blade. Concentrate on not pulling the blade to the side while cutting; this puts a tremendous amount of friction on the blade ana it will break quickly.

Soft metals come in a wide variety. Some, like aluminum and brass, are usually sold as alloys—they are combined with other metals such as nickel, lead, and anti

mony, which can dramatically change the hardness of the metal. For example, when antimony is added to aluminum, the result is still called aluminum but it is much

harder than plain aluminum. Similarly, lead can be added to brass to make it softer or nickel added to make it harder. Be very careful when selecting metal for a project. Cutting fluids are sometimes helpful, but usually not necessary when working with soft metals. (Editor's note: for more information on cutting metals, check out Ron King's article "Scroll Sawing Metals to Make Art and Jewelry," Creative Woodworks and Crafts, April '97.)

Paper cuts quite easily, but needs support to keep from tearing. It helps to put a piece of thin cardboard, like you would find on the back of a note pad, on the top and bottom of the stack of paper, then simply tape the stack as tightly as you can around the edges.

Plastics are prone to melting. There are several ways to overcome this, however. If the plastic still has protective paper on, leave it on while cutting, or glue paper or put masking tape on both sides where you will be cutting. Using a coolant such as lightweight oil or wax is another technique commonly used. Before sawing, check the vertical blade alignment of your saw and correct it if there is blade blur while tne saw is running. While sawing, do not flex the blade to the side while going around curves. If none of these steps works, then you need to use a larger blade.

Veneer and other thin materials are cut best when placed on a "backer" or substratum, which will make it easier to control the rotating motions necessary to follow the pattern. Your fingers are then pushing against a thicker edge. However, the material you have added as a "backer" must also be considered when selecting your blade.

Soft woods come in many varieties, and some are more difficult to cut than others. For example, you might need a thicker blade when cutting cedar if it has a high moisture content, as there is a tendency for it to clog in the teeth, causing extra friction, which in turn causes the blade to get hot quicker, resulting in blade breakage. With dry white pine, you can sometimes get a smoother cut with a larger blade because a smaller blade is not able to remove the powdery sawdust from the kerf, causing the blade to get hot faster. This frictional heat causes the blade to expand and "stick" in the kerf, tearing the fibers.

Hardwood species also have considerable differences between them. For example, cherry is much harder than walnut and blade choice will vary accordingly. Also, there can be a lot of difference in the density (weight) within each species, which will again influence "blade choice. ||