Aluminium strip and box section

This is the place for Technical Tips, Questions and Answers.

Postby Tony James » 18 Jun 2007, 11:03

Thank you Richard. True and very sensible observations. Couple of thoughts.

The Frame File is an obvious first stop although John Alexander's later edition - The Expanded Frame File is the one to go for. It has full details of Joe Beeby's metal frame. And John has an amusing way of warning of the vanishing wing nut!

I use wing nuts but not to undo and remove. That's the road to insanity. But they are useful when you simply slacken them, allowing the pieces secured to fold.

Now here's a little tip. Don't use a bolt so short that it is only just long enough or slightly over slackening will result in a lost wing nut. Instead use a slightly longer bolt. However you can still lose these when they work themselves loose which they always do. And you might just catch yourself or a puppet on the protruding bit of bolt. So cover this with one of those so called bolt or screw covers.

These are soft plastic, often black (I've seen other colours) and come in a range of widths and lengths but look like a tiny bearskin hat soldiers wear. B&Q used to have them until they got rid of their small hardware section. The last I bought came from a kite shop and are used for covering the ends of plastic kite struts. They're just a push fit.

You need as tight a fit as you can get but if there remains some movement use a drop of weak PVA glue to hold in place. Then should you need to remove the wing nut it will cut through the trace of glue.

Beware of using steel bolts and washers and wing nuts with aluminium. The two metals react together resulting in corrosion due to a cathodic reaction. I'm no expert but imagine you would get away with it if you used fibre or plastic washers between the bolt head and the wing nut and the ali strip.

The biggest question mark in my mind is the strength of ali outside and the wind factor. We all know how strongly the wind can blow but it's the gusts of wind which tests frames. Town centres can be very difficult - wind bounces off the buildings, specially in squares and can come at you from different directions at once, twisting the frame.

I'm beginning to wonder whether most of those post war 'aluminium' frames (either made in the then running down aircraft factories or from surplus wartime materials) were actually Duralumin and not aluminium at all.

Just out of interest those of you who work events where old fairground rides feature will have noticed Helter-Skelters or Lighthouse Slips as they are known. Tall, look like lighthouses and stand out on fairgrounds. Look hard and mentally lay the thing on its side and what have you got?

The fuselage of an aeroplane and that's what they were, more or less. Made at the end of the war in the aircraft factories from aircraft metal and using the fuselage jigs. War Surplus was the genuine thing in those days and exceedingly cheap. The post war fairs and circuses were equipped out of war surplus and all sorts still turn up.
Tony James

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Postby Chris » 18 Jun 2007, 16:19

As far as weight for weight goes. My wooden one certainly wasn't three times as heavy as my aluminium one - but I suppose it depends on the kind of wood and the section size used. My wooden frame was certainly made many years ago, and there was a much greater choice of timber to be had even in the supermarkets.
As for the potential corrosion of duralumin. Well mine stood up to a good few years of cruise work including being sprayed with salt water on one occasion. That rack, still uncorroded, held some of the displayed puppets at the Bantock house Lanchester "do" earlier this year. Actually you can get a type which is (or used to be) called Aluclad - duralumin core with the outer surface in pure aluminium. This was the type Eric used on aircraft. I believe that at the end of the war several puppeteers who worked marionettes built aluminium puppet racks.
Actually it is not the strength of aluminium which I question. In many ways it is very strong. What bothers me is its twistability and its bendability in wind. And when it bends I, unlike Billy, have found it very difficult to get back into shape.
Of course things vary with the area you work and the type of shows you do. If you work mainly indoors then you don't have the problem. But where I live on the North Wales coast we do have plenty of wind. And once the booth is up, and well pegged down, it is pretty secure. Yet if the wind is strong it tends to twist. Rarely do you have a head on wind - since you don't set up for the wind but for the position of the sun. Thus the booth tends to distort from the square, as much as the guy ropes allow, and over time the metal distorts too.
Mind you, you chaps who like to keep making and remaking just won't need to bother. Because the making is to me just a chore that has to be done to get me to the interesting bit - the performance - I like things to last. I know other people get tremendous enjoyment out of remaking and improving and adding and tweaking.



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