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Pop riveting is a
technique that is used to join thin pieces of metal and it can also be used
to join plastic sheet. The rivet has two parts; the pin and the rivet. The
pop rivet pliers are used to pull the pin through the rivet and as this
happens the rivet is deformed slightly so that it joins the metal or plastic
pieces. This is explained in detail below.
1. The two pieces of plastic or aluminium are drilled to a size slightly larger than the rivet
Pop rivet gun only £14.99
2. The pop rivet is passed through both holes in the sheet plastic / aluminium.
3. The rivet pliers are pushed on to the pin of the rivet and the handles are pulled together. As this happens the pin head is pulled into the rivet and the end of the rivet is expanded. Eventually the pin will break off leaving the rivet permanently fixed in position holding the two pieces of plastic / aluminium together.
A ONE-DAY WORKSHOP.
Held at Hampshire County Council Museum Service, on 18<sup>th September 2003.
Rivets are everywhere, both in museum collections and everyday life. Small rivets are found in jewellery, clothing and clocks; large rivets in ships, airplanes and bridges. They date back into prehistory, have been made of various metals, and are still used today. What I wanted to know was how are rivets applied, and could I do it?
The one-day riveting workshop, organised in conjunction with the Metals Section, was held at Chilcomb House, Winchester, the HQ of Hampshire County Council Museum Service. Acquired in the 1960’s the site now houses their reserve collections, conservation workshops, documentation, curatorial staff, design and exhibitions. The event was lead by Ian Clark (Ian Clark Restoration) with the enthusiastic assistance of the social and industrial conservators at HCCMS; Mark Holloway, Sean Wiles and Fred van de Geer.
Eight participants attended the course, each with different interests and metalworking skills, including museum and private conservators, a museum volunteer, a TV presenter and a sculptor.
Introduction to riveted objects.
Following a welcome from Alistair Penfold, the Principal Museums Officer (Collections), we moved to the Large Object Store for an introduction to the subject of riveting. The collection, which includes vehicles, engines and farm machinery was used to demonstrate how widely rivets have been used. Whilst we were shown the various generic rivet types it soon became obvious that there have been numerous designs and sizes of rivets tailored to particular functions, jobs and trades.
Ian went on to compare the relative merits of riveting with other joining methods (screws, bolting, welding), and showed us where several techniques had been used on the same object depending on the requirements of each join. Generally rivets tended to be employed in the construction of objects whilst nuts and bolts were more practical in the assembly of component parts.
Many of the exhibits in the store had been fabricated by hot riveting, a technique that we would try for ourselves in the afternoon. The main advantage of this process is the very tight join that can be achieved as the hot rivet cools, contracts and pulls the metal plates together.
Historically this was an important technique suited to seams that needed to be air, steam or water tight, and allowed the manufacture of structures such as boilers, tanks and ships. The seam also had the flexibility needed to compensate for any movement between the metal plates during use, when a stiffer welded join might have cracked. Before use, a hot riveted seam would undergo testing and any leaking rivets were repaired with a metal ‘caulking’ tool. This process which beats down the edge of the rivet leaves tell tale marks around the rivet head that could be seen on some of the objects.
Conservation / restoration concerns.
The conservation and restoration of riveted museum objects, particularly working exhibits, is a specialised area and the conservators discussed with us the points that must be considered before any treatment can be undertaken. The main themes were as follows.
Practical session – small rivets.
Back in the conservation workshop we looked at a display of objects from the collections that demonstrated riveting on a smaller scale. These included an Anglo-Saxon brooch with gold and silver rivets, a riveted wrought iron pipe repair cage and a metal riveted leather fire hose. Then, with the assistance of the conservators we had the chance to try our hand at the following small riveting techniques.
The morning ended with a chance to view the beautiful restoration work being carried out on a 1926 Thornycroft Petrol Tanker.
Practical session - pneumatic hot rivets.
In the afternoon things literally began to heat up as we watched a demonstration of pneumatic hot riveting and then attempted it ourselves. Ian began by running through health and safety precautions and in addition to our overalls and steel toe-caps we were issued with ear protectors and safety goggles.
A cylindrical steel test piece had been prepared with rows of holes in three different diameters. We would be using a portable pneumatic riveting gun with a repercussive hammer action and an inter-changeable concave domed head that gives the finished rivet its rounded shape. Various types of riveter have been used, this one was introduced around the beginning of the twentieth century. Throughout the afternoon Sean operated the pneumatic jam-back, a piece of equipment that fitted inside the cylinder to hold the rivet securely in place with enough force to resist the blows of the hammer.
The rivets were approximately 4” long with a pre-formed mushroom head at one end. Although originally they would have been heated in a brazier or forge we used an oxy/acetylene torch, as it is more controllable under classroom conditions. The quality and composition of the steel used for rivets would have been important and it therefore would have come from a batch of metal certified to be of a known grade.
During our attempts it took four participants working as a team to carry out the process. Since the rivet begins to cool as soon as it is removed from the forge speed is essential. The procedure was as follows:
The hammer action was very noisy and it took a lot of force to keep the riveting gun in place. As the holes progressively got larger more pressure was needed, and the riveting became competitive! With encouragement from the rest of the group we all managed to complete the ¾ inch diameter hole, although with my small frame I did need assistance. Along the way we managed to reproduce examples of badly formed rivets similar to those that had been pointed out to us in the large object store.
Removal of rivets.
Ian then demonstrated the following procedure for the removal of rivets.
The day ended with a quick tour of the other storage areas and conservation sections. We left with a comprehensive handout folder of interesting literature, and a surprising amount of knowledge and practical experience. We had also found a new respect for the skills of the industrial metalworkers who had applied hundreds of rivets a day.
Although this type of training day may not be directly applicable to the regular benchwork of many conservators it is invaluable for understanding metal objects. The information that we acquired will be very useful when discussing artefacts with conservation and curatorial staff, explaining techniques to museum visitors at public events, and giving gallery talks. It is also essential when assessing this type of object for tendering to specialist conservation companies. Oh yes, and with such good staff support it was a great deal of fun!
Applied Arts Conservator,
Museum of London.