STOP PRESS – Since I first posted this article I have discovered a source of original and genuine Avdel Rivets – as used by Jaguar in 1965 when building the XJ13. They aren’t made anymore and are damn expensive (just over £1 EACH and I need thousands ….) BUT they are the genuine article and I don’t need to resort to modern-day Chinese equivalents 🙂
“We need some rivets” said Paul at the bodyshop working on creating my 1966 XJ13 recreation).
“OK” I replied, “What kind do we need?“. Paul scratched his head and answered, “Dunno – I suppose we need to find out what Jaguar used in 1966“.
Little did I know that this exchange would lead to. It seems that rivets aren’t as simple and boring as I had first thought. For the benefit of others who may follow us along a similar path I thought it would be worthwhile recording what I learnt about rivets (don’t laugh – rivets really do have an interesting history). Ever wondered how primitive man over four thousand years ago attached handles to the first metal tools and weapons? You guessed it – rivets. How do you attach an aluminium skin to an airframe when aircraft designers switched from wood to metal? – rivets. How do you join almost any kind of dissimilar materials (wood, bone, metal etc) when you don’t have welding or adhesives? You got it – rivets.
Check out the following picture:
What do you think these are examples of? You guessed it (see the common theme?) – rivets. Only this particular rivet is from the late Bronze Age (1000 BC to 700 BC). It is a copper alloy rivet with two domed heads and has about eleven longtitudinal facets – probably resulting from manufacture. Some of these faces have longtitudinal grooves, perhaps caused when parts of the surface were shaved off with a tool. The more eagle-eyed amongst you will note the domed heads aren’t parallel to each other but are at about 18 degrees from each other. The size, form and condition suggest its probably a rivet from a late Bronze-Age dirk, rapier or sword.
But what has this got to do with Jaguar, the XJ13 or the price of fish?
Probably not a lot but, skip forward a few thousand years and place yourself in the shoes of the XJ13’s designer, Malcolm Sayer. A man steeped in aerodynamics and a former student of aerodynamics at Loughborough University’s Department of Aeronautical and Automotive Engineering. After graduating from Loughborough he joined the Bristol Aero Company where he worked on various projects including their radial engine. Aircraft and aerodynamics were in his blood and he naturally settled on the same principles of construction to Jaguar’s cars. Chief amongst these methods of construction? Go on, hazard a guess ….
The fasteners of choice in 1965/66 were “Avdel” – short for “Aviation Developments”. Anyone think (as I did) that “rivets were rivets” and were pretty much like today’s pop rivets? There’s a bit more to it than that. The clue as to which rivets were employed by the builder of the car (the late talented Bob Blake) was given by Peter Wilson (someone who can genuinely lay claim to having participated in the build of the original XJ13). Peter recalled Blake’s use of “Advel” rivets and the fact that the car “looked like a porcupine” during its build. Those of us who have used modern “pop-rivets” will know that the stems are broken off during application but the stems of the original Advel rivets remained in place and the protruding stems were later cut off and the face of the rivet shaved flat. When the rivets were first applied the sticking-out stems gave the “porcupine” effect.
So how did these Avdel rivets come about?
In 1936 from a small shed in Godalming Surrey Stanley Thomas Johnson started a business called Aviation Developments.
The company was established to manufacture & supply riveting technology, to a number of industries, but primarily for the rapidly developing Aviation industry. This industry was soon to mushroom as the world responded to the antics of a moustachio’d individual after 1939. In 1936, wood was rapidly giving way to aluminium for aircraft manufacture and a reliable means of fastening was required. Initially these aluminium and steel structures were assembled using solid rivets that were slow to install, requiring two operators with access to both sides of the components to be assembled.
Working with the pioneering UK Aviation Engineers of the time one of Aviation Developments Engineers, Jacque Chobert, invented a radical new riveting technology, the Chobert® riveting system.
Initially Chobert® fasteners could only be installed one at a time. Aviation Developments Engineers soon recognised this limitation and set about developing a tool capable of installing multiple fasteners before requiring reloading.
The Chobert® system allowed rivets to be installed by a single operator using a hand tool accessing one side of the riveted joint – significantly reducing both assembly times and costs. The concept of assembly from a single side of the application became generically known as blind fastening. This advanced system was quickly adopted by the UK Aviation industry and proved invaluable in building more than 20,000 Spitfire fighter aircraft (yes – you read correctly – 20,000 Spitfires) over a period of eight years that were key to the success of the Battle of Britain.
During the late 40’s and 50’s the global aviation industry moved into the jet age and sales of the Chobert® increased as it became an industry standard fastening technology.
As well as expanding both the range and sales of the Chobert® system the company developed engineered fastener and assembly solutions for other industries. Unsurprisingly, Malcolm Sayer adopted these types of fastener for prototypes and racing cars. However, he did continue to make use of hand-applied countersunk solid rivets to minimise disruption to airflow where needed. The following picture shows examples of solid rivets which could only be applied if there is access to both sides of the join:
Malcolm Sayer was very much a perfectionist when it came to the aerodynamic properties of his designs and used these countersunk rivets as far as practicable. Indeed, Peter Wilson recounts in his definitive book on the XJ13 …
“… Bob Blake had found a small winged Jaguar badge which he thought would look rather nice on the front of the car. He carefully made a depression in the nose panel, the exact shape of the badge, such that it sad almost flush with the skin surface. No sooner had he done this that Malcolm Sayer made one of his regular visits to the shop to see how things were progressing. Malcolm took one look at the badge and obviously did not like what he saw. He asked Bob who had fitted it. ‘I did’ said Bob. ‘Well take it off!” Malcolm insisted. ‘It will disrupt the airflow over the front of the car.’ … Bob removed his badge and beat out the depression.”
The nose of the original 1966 XJ13 was left smooth by Malcolm – presumably for aerodynamic reasons. However, one of the many changes made during the rebuild of the crashed car in 1972/73 was the addition of a row of domed rivets across the nose of the car – clearly wrong when compared with the 1966 original. Needless to say, my 1966 recreations have the smooth nose Sayer intended.
Yet another difference is that the rivets used during the rebuild were larger than those used originally. This was probably because the original rivets were drilled out and so larger ones were now needed to fill the enlarged holes.
By the 1950’s Aviation Developments was focusing on providing new assembly solutions. The two part Avdel® breakstem aerospace rivet was introduced offering improved rivet strength, different head configurations, diameters and material options. When installed the stem breaks above the head and is machined off. When painted countersunk forms of the rivets where almost invisible. These fasteners were used in many areas of the aircraft including ailerons, flaps, engine pods, elevators, rudders, tail planes, fins, doors & floors. In 1961, to reflect its broadening product portfolio and cross-market/industry capability, Aviation Developments changed its name to Avdel® and opened its new manufacturing facility in Welwyn Garden City, Hertfordshire.
One of the first products developed by Avdel was the Avex® multigrip breakstem rivet. It was introduced to the market with the compact 734 hydro-pneumatic hand tool. The world’s first multigrip fastener quickly became a flagship product for Avdel that would remain unchallenged across automotive, industrial and electronic market sectors for the next 20 years. It is this product that was almost certainly used by Bob Blake when building the original XJ13.
Advel the company still exists today and they offer a close equivalent to the rivet originally supplied to Jaguar.
Sadly, the Avdel manufacturing facility at Welwyn Garden City was closed down in 2005 and manufacturing was transferred to Wuxi in China.
The words Jaguar, Jaguar XJ13, XJ13 are used in a historical/descriptive context and in no way suggest our recreations/replicas are approved by Jaguar. It is widely known that there was only ever one Jaguar XJ13 and any others can only ever be replicas, facsimilies, tributes, recreations, toolroom copies or similar.