Grinding wheels used in welding and fabrication are strong, tough tools, but many in the industry have called them "rocks" or "stones," implying that they're unbreakable.

Watching the sparks fly as his dad welded a temperamental posthole digger mesmerized Derek Arnold. "I found the immediacy of something so permanent absolutely fascinating," he said. "I knew I wanted to weld."A hands-on welding education on the family farm drove Arnold to take his skills and creativity to the next level. In 1993 he graduated from the Maryland Institute College of Art in Baltimore. "I've been welding regularly since my freshman sculpture class," he said.

For about 40 years, a great debate in welding is whether to use constant-current or constant-voltage power supplies when using gas metal arc welding on aluminum. Constant-current power supplies made sense 30 years ago and are still used in some applications today, but for most applications, constant-voltage power supplies are suitable for gas metal arc welding aluminum.

When you heat or cool a piece of metal to a specific temperature, that metal goes through what's called a phase change, in which its crystal structure changes. Sometimes the change is obvious. For example, when a piece of metal melts, it goes through a phase change when the crystal structure breaks down and the metal goes from solid to liquid. When it solidifies it's also a phase change, as the structure re-forms from liquid to solid.

New methods for cutting tube and pipe have been introduced to welding shops in the last few years—methods designed not only to cut metal, but also to cut costs.

Some call them rosebuds, others call them multiflame heating heads, and a few call them heat sticks. No matter what you call torch attachments, this article is a frank discussion about these tools that use oxygen and a fuel gas to make a lot of heat quickly. When used properly, they can make quick work of many heating jobs.