How to Cut Perfect Holes in Metal
In response to a question about how he cut the holes in the steel wings of a private art commission without any discoloration or roughness, Kevin shows how to use a hole saw.
First he shows the attachment that has a pilot drill to help get your hole started. The attachment has a locking mechanism with pins that lock into the holes in the back of the hole saw to keep everything together. You screw the locking mechanism into the hole saw, line up the holes and screw it down so everything locks together.
The hole saw has a bimetal cutting surface that dissipates heat well while staying sharp. Hole saws come in lots of different sizes, too. Kevin shows some of the ones he has, from 1/2" to 7/8" to 3" to 4". You can buy them as a set, but the sets he's seen only go from about 1/2" to 3/4" or require a big case to store them all in - hole saws come as large as 6", 7', 8" and 10".
The smaller diameter hole saws can be used in a handheld drill or a drill press, but the bigger ones perform better in a drill press because they can pull the metal or wood loose. With hole saws larger than 1-1/2" Kevin uses a drill press, clamping down the material on the drill press table. You can also buy hole saws individually. All of his came from Home Depot. Kevin has had good luck with the Milwaukee brand. There are also hole saws made of different types of metal and adjustable ones. He recommends going online and researching "hole saws" to see what is available.
As for using them to create a project, he laid out his bottom row along the straight edge, then measured in and across. Then he cut some 4" diameter circles out of paper and laid them on the metal so he could get his spacing right. Next he took his spring-loaded center punch and punched right in the center of the paper pattern.
Kevin takes a moment to explain how the spring-loaded center punch works. You put it up against the metal and press down. You hear a little "snap," which is the spring releasing a small hammer inside, which makes a dimple in the metal. You can come back with a traditional center punch and a hammer if you want to create a bigger mark, but using this spring-loaded center punch seems to do the job well enough for the hole saw's pilot drill to find the center point. (Sometimes he does it twice to deepen the dimple.)
Finally, he demonstrates how to use a hole saw. He puts a hole saw on his drill press, center punches a piece of aluminum, clamps the metal to the table, and drills a pilot hole through the aluminum. He then lowers the hole saw and cuts right through the metal.
Aluminum cuts more easily than steel; he uses cutting fluid when using a hole saw on steel. When he drilled the wings for his art commission, he clamped a large piece of wood to the drill press table, then clamped the metal to the wood to keep everything straight, and went a little more slowly.
Kevin has cut 1/4" and even 1/2" steel using the drill press and a hole saw. To see the art commission mentioned in this video, visit http://www.kevincaron.com/art_detail/lady_bugme.html.
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