Riveting is a fixing technique whereby metal parts are fixed to each other using metal pins known as rivets. Between 1875, when there was a major increase in building ships using iron, and 1950 all metal ship structures were riveted; from 1950 onwards riveting was almost replaced entirely by welding. Due to the use of riveting in a number of famous historic ship restorations the interest in riveting is starting to increase, also amongst private ship owners.
Materials and tools
In addition to the metal parts that have to be fixed together, you will need the following tools for riveting: a furnace (image 2) for heating the rivets, a punch and a drill for making holes in metal, a cutting and bending tool for making the metal parts into the required size and shape, a riveting hammer (image 21 and image 9), dollies (image 24) in various shapes and sizes and tongs (image 1) for holding the hot rivets. Riveting is hard work, that was previously undertaken using hand tools. These days pneumatically and electrically-operated tools are used in addition to the hand tools. Wear heavy-duty gloves, a face mask and hearing protectors.
Three or, preferably, four people are required for riveting: the catcher, the riveter, the holder-on and the heater-boy, who heats the rivets until they are red hot and then passes them on. The catcher (or the heater-boy in a three-man squad) pushes the red hot rivet into the hole. The riveter hits the rivet into the hole using the riveting hammer. The holder-on holds the rivet on the opposite side using a dolly. The following steps are performed for riveting:
- First of all you must accurately prepare the metal parts that have to be fixed to each other. Measure out new metal parts exactly and cut or grind them to size; the parts must be flat and without burrs. Bend or hammer the metal into the required shape as required. Existing metal parts must also be flat and clean and free from burrs, rust and other irregularities. This is important because you can only achieve a good fixing when the metal parts match each other and abut each other over the entire length of the riveted joint.
- Now measure the locations for the rivet holes, mark them, and drill them (or preferably punch them out). Attention: when drilling the holes in particular, make sure there are no burrs or metal swarf remaining around the holes that can get between the rivet joint. In the past, a pendulum punch was used for making the holes in the metal plate (image 26 Gijs, NB photo MvL): a machine with a heavy weight at the end of a pendulum that you could swing around by hand and which generated so much force that you could punch a hole through steel. These days hydraulic or electric punches are used. Size the hole so that a rivet fits through it exactly.
- The holes in the metal parts that have to be fixed together must be located precisely opposite each other. The rivets are to be equally spaced. The distance between the rivets is called the pitch.
- The holes on the side which will have the head of the rivet (the inside) are countersunk. A drill with a broad cone-shaped head is used to make the hole slightly wider so that the red hot rivet is easier to insert.
- Connect the metal parts temporarily at a few places using a few nuts and bolts; these will be removed later.
- Select the correct thickness and length of rivets to be used for the work piece. The length of the rivet is determined by the thickness and the number of metal parts that have to be fixed together. For thicker plates or for fixing more than two plates together longer rivets are required. If necessary, rivets can be shortened until they are at the correct length.
- Heat the furnace or forge. A coal-fired forge was used previously to heat the rivets but that could cause the rivets to become too hot and melt. These days a gas-fired furnace is used. The advantage of this is that it is easier to control the temperature so that the rivets do not become too hot. Another benefit is that a gas-fired furnace is lighter and smaller and can be taken to the site (image 4) where the riveting is to be undertaken.
- Heat a number of rivets in the furnace until they are red hot (image 5).
- Remove a red hot rivet (image 6) from the furnace using the long tongs. Work quickly to prevent the rivet cooling down too much, which would make it harder to work (image 23). Push the rivet through the hole from the inside of the work piece (image 13).
- The holder-on holds the rivet in place using a dolly (image 14). This is a strong piece of iron with a flat head. This is hard work because the holder-on has to absorb the blows on the rivet by the riveter on the other side of the hole (image 10).
- The riveter now hits the protruding side of the rivet (image 15) until the end is flat (image 18) and up against the metal plate (image 17). The metal parts are now fixed together strongly. As the rivet cools down it contracts slightly and draws the plates even more strongly together. In the past the riveter used a hand tool for this, a riveting hammer. There were also two riveters that hit the rivet in turns. In this way it was possible to work faster, given the rivet less time to cool down. These days the riveter generally uses a pneumatic riveting hammer, operating on air and for which a compressor is required.
- In the meantime the heater-boy has prepared the next rivet so that he can insert it into the next hole (image 16).
- NB (1) Proper preparation and flattening of the edges of the metal parts that are to be riveted together is very important. If space remains between the metal plates rust will form. Rust ultimately forces the riveting apart. What is striking is that there is usually no rust on old metal plates along the riveted joint; a sign of good riveting.
- NB (2) In the past tar paper was inserted between the riveted joints in order to prevent rust formation; it appears, however, that this is no longer available.
- NB (3) If the riveted joint has to be completely watertight the edges of the metal parts are hammered over each other after riveting using a hammer and chisel.
Gas furnace for heating the rivets
Riveting squad working on board
Red hot rivets in the furnace
Heater-boy grabbing a hot rivet
Pneumatic riveting hammer (2)
Riveting squad: riveter, heater-boy and holder-on
Heater-boy pushes rivet into the hole
Riveting tools: rivet tongs, riveting hammer and dolly
Riveter and holder-on riveting up
Riveting squad ready for the next rivet
The result: flat rivet
End of rivet is hit until flat
Pneumatic riveting hammer (1)
Red hot rivet inserted into the hole