Joined: Aug 2017 Posts: 1,922 Threads: 90
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Location: Ripon
I'll add to the comments about over-engineered design. GE and Colin Chapman were both great believers in adding lightness wherever possible and it is a common error to conflate thickness with strength.
If you're planning punishment for the finished car flexibility can be an advantage over rigidity and a flexible construction is less likely to be damaged.
I'd also stick to birch ply which is surprisingly strong in thin sheets. Thick birch ply is usually heavier than the ghastly far eastern rubbish and is much better quality manufacture. You are unlikely to find overlapped laminations and "through voids" with birch ply. This will allow for thinner material to be used.
Joined: Aug 2017 Posts: 3,217 Threads: 100
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Location: Darkest Bedfordshire
I used 1.5mm aircraft ply (from Chiltern Timber) for my Ulster rep's interior trim panels, and it is wonderful stuff! You can cut it out with scissors, roll it into a tube without splitting it, and yet with a slight curvature it makes a stiff panel. Weighs next to nothing.
Joined: May 2018 Posts: 1,918 Threads: 102
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Location: Llandrindod Wells
Car type: 29 Special, 30 RK, 28 C Cab
Thanks Ian, Duncan and Chris
Food for thought. Ian, your special looked a handsome car and similar to the look I was after. It seems I can drastically reduce the thickness of the skins of the sandwich I was considering and even leave one out!!
I may post the next progress report in a separate thread given the interest that has been generated. I'm restoring some Chummy scuttle headlights today, a Beaulieu purchase from last weekend!
Cheers
Howard
Joined: Aug 2017 Posts: 1,666 Threads: 46
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Location: Auckland NZ
Car type: 36 Nippy, 31 RM, 38 Special, 24 Works Rep
Howard, I attached a 1/8" ply trim panel inside the body with cup screws which would have completed the sandwich stiffening the sides to a point.
Black Art Enthusiast
Joined: Aug 2017 Posts: 862 Threads: 16
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Location: North Yorkshire
Having built various specials over the years, I would advocate using plywood! Never mind the expensive aircraft grade stuff, we are talking about Austin 7's. I use normal birch plywood in 3mm and 4mm thickness, if you build up the edges by laminating so they are around 12mm thick you get an incredibly strong structure. I use Evostick Resin W glue (the waterproof variety).
The Pytchley Special was built this way, the floorpan was based on my RL saloon and was made out of a single 8' x 4' sheet of 10mm plywood with 1" x 1" ash timbers along the edges of the transmission tunnel and rear heelboard.
If I was building an open Austin 7 special, I would base the body on an MG M-Type or Austin 7 Mulliner, similar to Ian's car featured above.
I achieved a fabric finish by covering the plywood shell with thin curtain lining material glued on with varnish, then an eggshell paint finish. Much cheaper than a normal fabric finish and it does not have that plasticky over stuffed look. It has been on about ten years and does not seem to be deteriorating.
Joined: Mar 2015 Posts: 5,196 Threads: 223
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Location: Scotchland
Howard,
You and Malcolm will be able to chat about this at Guildtown in person - you will also be interested in the special display tent organised as part of the GE focus, I am confident it will provide you with very useful information for your project.
Joined: Aug 2017 Posts: 1,666 Threads: 46
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Location: Auckland NZ
Car type: 36 Nippy, 31 RM, 38 Special, 24 Works Rep
Brilliant I bet the smell was fabulous!
Black Art Enthusiast
