National Post February 12, 2007
By David Grainger
Aerolithe Part Four
(The Secrets of Elektron Revealed)
Making the T 57 Bugatti Aerolithe body from magnesium seemed at first to be an easy thing to accomplish. Three weeks spent experimenting with magnesium alloy; an alloy once called elektron proved that nothing that we knew about forming aluminum, steel or any other metal applied to elektron. In the last column I described the challenges; here is how we got around them.
First, magnesium burns and does so with a light so bright that you can't look at it. This was our first concern. Just what is required to get it burning and more importantly, how do you extinguish it once it is involved? These are important considerations considering that the forming of metal and most especially its joining generates or requires heat.
We found that it is not as easy to ignite as one might think and that it is the ragged edges left from cutting it which look a little like broken plywood that are vulnerable to ignition. File those edges round and the risks are reduced greatly. Next of course, the filings and dust created while working magnesium are far more dangerous. The solution to that is a continuous cleaning process where each task is cleaned up on an ongoing basis, a bit of a challenge for the metal shop at times.
Magnesium's reluctance to bend like aluminum left us shaking our heads for a day or so. Every time we tried to from it, it would bend a few degrees and then snap.
It did not look good; we were not achieving even fifty percent of the angles we required to create the coachwork. Another discovery was made as well. If you tried a compound curve in two parts the material would forget the first bend as you were implementing the second, wanting to only take a simple curve and having an incredible molecular memory. Looking into the molecular composition of the metal we started to understand the challenge. Magnesium is composed of hexagonal molecules and these in relationship with its crystalline structure give it many of its unusual properties.
We did discover that in mass it was fairly difficult to set on fire so that opened the door to two processes that we thought might be barred to us. The first was welding. In order to create the coachwork it was becoming obvious that we were going to have to create each major panel from lots of little pieces and to accomplish this we were going to have to weld them.
Experiments with inert gas welding and using magnesium welding rod showed that it welded beautifully. The inert gas raises the safety level denying combustion.
That however did not solve another problem. We could not make some of the short and acutely curved sections by welding dozens of tiny little bits so how were we to do it? The solution required heat and just enough to make the material slump without turning it to a combustible liquid. Believe it or not, within short order we were slumping flat sheets of magnesium over a curved from and using oxy acetylene flame to accomplish it.
When I first heard they were experimenting on the floor below me with welding flames and magnesium I had a little conniption, visions of burning Bugattis, 50s classics, Muscle Cars, Exotics and one off Customs dancing through my head. The project manager, Mat Radman and I took an Oxy Acetylene unit outside along with a small chunk of magnesium. We also had a fire extinguisher to determine if it could be put out. Magnesium will burn in both a nitrogen atmosphere and carbon dioxide. Getting it going was no problem but it was just the edge that started to burn. The eye burning white flame was incredibly intense but moved rather slowly across the material. We used the extinguisher on it which actually did not extinguisher the flame as much as blew it into tiny pieces that burned themselves out quickly. Still, not ideal for in house work. The solution was to furnish vats of water into which the magnesium could be dropped and submerged. Its slow flame crawl rate would allow ample time to accomplish that feat.
So safety insured, we now had the beginnings of an incredibly elegant, strong and atmospherically light car body.
Curves could be created by slumping over forms; we could weld it and grind down the weld lines to invisibility and with a combination of English Wheel and Planishing Hammer we could make small pieces bend into the shapes that we required and keep their shape.
We had also determined that there was nothing that we were doing that the craftsmen of the thirties could not do just as well or better with the exception of welding with inert gases, but the same could be accomplished without inert gas, just with a little more concern for safety, and one has to remember that in 1935 you could still ride a bicycle without a helmet.