Jim Chestnut worked as a trim subcontractor in Connecticut in the mid-1990s when he first ran into the Hartford #62 Miter Clamp. The ingenious device wrapped around the mitered corner of door or window casing and pulled the joint tight with the flip of a lever.

Chestnut, a man who values a gap-free miter more than most people, was immediately intrigued.

“I saw how well the Hartford worked,” he said, “and basically decided I could make it work better.” It didn’t take long for Chestnut to produce his own version, the Clam Clamp.

Chestnut builds the 2 1/4-pound clamps from stainless steel and solid brass so they won’t rust and won’t wear out. Each of the right-angle legs of the clamp is equipped with small nickel-plated alloy pins that engage the edge of the casing. As the clamp’s handle is rotated, an internal cam forces one of the jaws inward. The pins grab the casing and the joint closes as tight as, well, a clam. The clamp can be used on paint or on stain-grade trim.

The Clam Clamp holds so tenaciously that as soon as the casing pieces are glued together, with or without a reinforcing biscuit, they can be picked up by one leg and hauled around the house without fear anything will come apart. Armed with a short stack of Clam Clamps, a trim carpenter does the work “better, faster, cheaper,” as Chestnut would like to tell you, saving the client money and increasing profits.

Other than the stamped metal plates of the clamp bodies and the screws, Chestnut fabricates all the parts and assembles the clamps in his small machine shop in the Florida Keys. A pair of clamps sells for $140, and discounts apply for volume shopping.

You can learn more about the clamps and tap into a library of trim-carpentry tips and techniques by visiting Chestnut’s website at miterclamp.com.