A question for you body builders

[Nick Lettington]

I have a Speedex Silverstone shell that is in poor condition and plan to strip out the existing corroded (but probably factory) steel mounting frame in favour of a more simple loose skin approach over a basic lightweight tube frame, akin to Keith Jenkins' (now John Paul Davies') car (pictured below)

I'd like to form some stiffeners to prevent the fragile fibreglass from deflecting, using thin sheet aluminium with holes with folded edges for stiffness without adding too much weight.

Can anyone advise me of the thinking behind selecting a grade and thickness of aluminium to use and the best way to form the edges of any cut outs.

I seem to remember Ian Williams posting some great pictures of forming panels for his special, but am struggling to locate them on here. I also seem to remember a white plastic chopping board being butchered to make a suitable tool..?

Any advice gratefully received, particularly in the form of step by step photos.

Also... if I may, If anyone has a Ruby chassis (in any condition)...

TIA

Nick

   

[Ruairidh Dunford]

Was it when Ian made the pressings in the new bulkhead of his Nippy?

[Nick Lettington]

I think so Ruairidh, but the old grey matter is struggling a little!

[Ivor Hawkins]

Having owned a number of Lotus Super Sevens over the years, I know Mr Chapman would have had half of those tubes out!

In answer to your question, would laying up paper rope strengthening ribs solve the problem?

[Nick Lettington]

Keith and John Paul are of the same mind!

[Ian Williams]

I was when I made the new body for my special, I am happy to repeat and clarify anything for you but if someone can find the body building thread I will save me a lot of repetition.

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https://www.austinsevenfriends.co.uk/for...hp?tid=332

Not sure if this will work??

[Nick Lettington]

Thanks Ian it works perfectly. 

What grade/ thickness of sheet did you use?

[Ruairidh Dunford]

A very nice car, that.

[Ian Williams]

Thank you Rury, that is kind. And I am pleased it helps you Nick, if any specific questions arise I will do my best to answer them for you. The car its self has languished in storage for the past couple of years as I have been through some major upheaval in my life. I recently collected it and brought it back down to my new home in Wellington, hopefully I can start working on it again soon, I will update the thread once that happens.

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I think I mainly used 1.6mm 5005, I would have annealed before working and it work hardens quite quickly, some of the structural panels will have been 1.8mm and there was probably a little 1.2mm used in some places.

[Duncan Grimmond]

I remember being impressed by Ian's techniques in his bulkhead pressing, excellent guide there. I'd also think about buying a set of dimple dies, usually available on ebay, very useful for strengthening/lightening holes in ribs with flanged edges. I tend to use 1.5mm 1040 grade aluminium as 1060 can be a bit hard to form and annealing evenly can be tricky particularly on stressed members.