holder-up
A bucker; one who bucks rivets, typically holding a heavy bucking bar against the bucktail of a rivet (heated if necessary till it is soft), while the riveter (or gunner or, before mechanisation, basher) uses a rivet gun (an adjustable-impulse pneumatic hammer) fitted with a rivet set, against the factory head to provide impulses which upset the bucktail into a field head.
holder-up: the anvil end of riveting
A holder-up is a tradesperson who supports the bucking bar during riveting operations. While the riveter operates the pneumatic hammer from the factory head side, the holder-up presses a heavy bucking bar against the opposite end of the rivet, providing the reaction force needed to form the field head. This is manual work requiring strength, timing, and the ability to withstand heat and noise.
The bucking bar itself typically weighs between 2 and 8 kilograms, depending on the rivet size and material being joined. Mild steel, aluminium alloy sheets, and structural steel are common substrates. When riveting hot, the holder-up must keep the bar in firm contact with the softened bucktail as the rivet set delivers rapid pneumatic impulses, usually at 2,000 to 4,000 blows per minute. The bucking bar does not strike; it simply resists, allowing the expanding rivet shank to plastically deform and fill the hole completely.
Variants and conditions
On structural steel work, hand-driven rivet guns are rarer, but where they exist, the holder-up's role is more intense. With pneumatic guns, the holder-up can work alone or with one riveter, depending on access. On large assemblies, scaffolding or temporary platforms position the holder-up to reach bucktails inside fuselages, ship hulls, or boiler drums. In these confined spaces, heat radiation from hot rivets can be severe, and proper ventilation or shielding becomes critical.
The position demands constant alertness. A bucking bar that slips risks damaging the surrounding sheet, wasting the rivet, or striking the holder-up's hand or arm. Fatigue degrades control. Many workshops rotated holders-up every two hours to maintain quality. The term itself is straightforward: the holder-up holds the bar up (or in place) against the load.
Mechanical and automated riveting has largely superseded hand and pneumatic methods in aerospace and heavy fabrication since the 1970s, reducing demand for skilled holders-up. Where hot riveting persists in heritage fabrication, bridge repair, or boilermaking, the role remains essential and physically demanding.