What Is a Bucking Bar?
What a bucking bar is and how it works
A bucking bar is a solid, dense metal block held against the tail of a solid rivet while a rivet gun drives the manufactured head. The mass of the bar reacts against the blows from the gun, so the rivet shank upsets and forms a tight shop head.
How a bucking bar works
Solid riveting takes two people or two hands. One side runs the rivet gun against the manufactured head. The other side, the bucker, holds the bucking bar flush and square against the rivet tail. As the gun hammers, the inertia of the bar forces the shank to swell and flatten into a shop head. The bar has to carry enough mass to react the blows, and it has to be held flat so the head forms evenly rather than tipping to one side.
Why bucking bars are made of tungsten
Mass is what makes a bucking bar work, and density is how you get mass into a usable size. Tungsten alloy is roughly 2.5 times denser than steel, so a tungsten bar delivers the same backing mass as a steel bar more than twice its size. That compact size is what lets you reach confined structure, hold the bar square, and work a long session with less fatigue.
Choosing the right bar
A bucking bar is chosen by three things: shape to match the access, weight to match the rivet size, and length to reach the joint. Start with how to choose a bucking bar, or run your inputs through the Bucking Bar Selector.
Common questions
What does a bucking bar do?
A bucking bar backs up a solid rivet while it is driven. Held against the rivet tail, its mass reacts against the rivet gun so the shank upsets into a tight, even shop head.
Why are bucking bars made of tungsten?
Tungsten alloy is about 2.5 times denser than steel, so it packs full bucking mass into a smaller, more controllable bar. That gives better access, a squarer hold, and less hand fatigue. See tungsten vs. steel bucking bars for the comparison.
How heavy should a bucking bar be?
Match the weight to the rivet size: lighter bars for small rivets and light gauge, mid-weight bars for general airframe rivets, and heavier bars for large rivets in thick structure. The bucking bar weight guide breaks it down.