December 2011 / Volume 63 / Issue 12|
Making the most of metal sawing
By Tom Lipton
Saws are extremely efficient at cutting almost any material. Many metalworking shops underutilize their sawing dollars by machining or grinding material that could be sawed more efficiently. Sawing is more efficient because the operation’s thin kerf minimizes material waste and typically requires less horsepower to remove material than other processes. And the chunk scrap produced by sawing has a higher per pound value than chips from turning or milling.
If you’re just setting up a shop and thinking about what kind of saw to get, I strongly suggest a vertical bandsaw. It’s highly versatile and can cut almost anything—from meat to hardened steel to even glass. The key factors when selecting a vertical bandsaw are speed range and throat depth. Buy the maximum you can afford for both.
One of the great abuses of bandsaws is not changing the blade for cutting thicker material or different alloys. If I had unlimited floor space and a budget to match, I would have three vertical bandsaws, each set up differently to accommodate different materials and alloys.
The rule of thumb for blade pitch is to use lots of smaller teeth for thin stuff and fewer but bigger teeth for thick stuff. For most purposes, a shop can get along with two blade pitches. This helps reduce confusion for people who don’t reference the blade chart.
Band saw blades are often purchased in bulk on a roll, and in some operations the saw blade is intentionally cut prior to use. As a result, the blade ends often must be welded together.
If you don’t have a blade welder or you run out of silver solder, you can tungsten-insert-gas weld bandsaw blades with silicon-bronze rod. The weld is annealed a second time after grinding to remove brittleness along the heat-affected zone. Be sure to accurately line up the blade spine or it will make clicking noises as it runs through the guides.
After you weld, silver solder or otherwise connect the two stray ends of a bandsaw blade, remove the weld buildup and level the seam. Use a curved surface to expose the weld area to your grinding or other preferred abrasion operation. After grinding, peen the weld area on a flat dolly to level the seam so blade thickness is correct.
Before sawing with any kind of saw, protect critical surfaces with tape. A good grade of masking tape works well for a cutting guide as well.
Other types of saws that make a good investment are circular and miter saws. Use a woodcutting circular saw to cut aluminum plate. Be sure to wax the blade. Use the cheapest carbide-toothed blades you can find because high-quality blades don’t seem to last any longer. I have cut 2 "-thick copper with this setup. If you use a guide, you almost have a plate saw.
A woodcutting miter saw makes short work of aluminum and plastics. I add a fence with a recessed scale to prevent scraping off the stick-on ruler. With this setup, sawing 4 "-dia. aluminum is a snap.
Use a push stick to sweep the scraps off the saw table. Sweep from behind the blade toward you. If you were to accidentally hit the blade, you would get a good scare but still have all your fingers because the last time I checked there are no teeth on the back of the blade. CTEAbout the Author: Tom Lipton is a career metalworker who has worked at various job shops that produce parts for the consumer product development, laboratory equipment, medical services and custom machinery design industries. He has received six U.S. patents and lives in Alamo, Calif. Lipton’s column is adapted from information in his book “Metalworking Sink or Swim: Tips and Tricks for Machinists, Welders, and Fabricators,” published by Industrial Press Inc., New York. The publisher can be reached by calling (888) 528-7852 or visiting www.industrialpress.com. By indicating the code CTE-2011 when ordering, CTE readers will receive a 20 percent discount off the book’s list price of $44.95.
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