Strenghtening plasticard.

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Boxcar Willie
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Strenghtening plasticard.

Postby Boxcar Willie » Tue May 13, 2014 11:34 pm

Last night I sat at the kitchen table and spent a very pleasant couple of hours building a representation of the old CIE "B" wagon - the Bulleid designed corrugated ones that were everywhere in Ireland in the 60s and 70s. I had a donor Airfix chassis and set about making a superstructure from corrugated plasticard. The effect was quite pleasing - I managed to capture the "feel" of the subject if not the exact dimensions and the wheels aren't correct but a man on a galloping horse wouldn't spot it.

Anyway I found that the plasticard was a tad too weak and bendy (it's the stuff used to make corrugated roofs on sheds and the like) so I was obliged to glue it to some ordinary flat plastic. This meant that the inner surfaces of the wagon were smooth whereas they should, of course, match the outside and be, well, corrugated. If I put a load of coal or suchlike in it'll be covered up and so won't matter but I'd like to know if there's another method of strengthening the corrugated card without bracing it or glueing it to a base as I did.

Here's a pic of a "B" wagon:

Image

and here's a pic of my model:

Image

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Peterm
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Re: Strenghtening plasticard.

Postby Peterm » Wed May 14, 2014 12:29 am

Unfortunately, the only way I can think of doing it is by lamination. Corrugated, thin plain, then corrugated again. Using an odd number should prevent warping.
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Boxcar Willie
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Re: Strenghtening plasticard.

Postby Boxcar Willie » Wed May 14, 2014 12:34 am

That would work but the result might be too thick. I could, of course, use thin sheet metal for the centre lamination - that'd add a bit of weight as well. I will experiment further.

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Bufferstop
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Re: Strenghtening plasticard.

Postby Bufferstop » Wed May 14, 2014 9:28 am

In proportion the prototype must have had the same problem. When I was young most houses had the remains of wartime Anderson shelters in their back garden. Across the direction of the corrugations the sheet was quite bendy. The wagons must have had some form of bracing to avoid being deformed by the load. Perhaps a slight exaggeration of the bracing would add the strength you need. The top edge and the drop door frame look like contenders, making them a bit deeper rather than thicker might add the strength. Looking at the prototype you can see that the corrugations taper out to leave a vertical flat area which adds to the strength, you might get away by using a T shaped section either side of the door (the top of the T being inside). It may not be prototypical but an L section brace inside each corner may also help. The various panels are hot stamped to have the "flutes", access to a vacuum forming rig might be the ideal way of producing these panels in scale.
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alex3410
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Re: Strenghtening plasticard.

Postby alex3410 » Wed May 14, 2014 9:55 am

add some extra support in the form of metal pins? should be nice and strong but also small enough to blend in nicely when painted

could add some near the door section as well as at each end?


alternatively (no idea if it would work!) could you flatten the bit of plastic under something flat and heavy and maybe apply a little heat (low temp in oven? hair dryer?) to get it to hold its new shape? - not my fault if it all melts into a blob :lol:

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Re: Strenghtening plasticard.

Postby Bigmet » Wed May 14, 2014 10:10 am

Learn something new everyday, I had no idea such a design existed. Really interesting.

Trying to fabricate in metal: difficult. If it is soft and thin enough to take the corrugations it will be too weak alone. Thin flat sheet of tough and hard material with thin overlays soldered on both sides will be too thick.

I'd try ti with two sheets of corrugated plastic alone, laminated with mekpak. It may warp slightly over time, but that real wagon isn't all square either.

There are technologies that could make it accurately, my favourite would be nickel electroforming. That would come eye-wateringly expensive though...

peak experience
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Re: Strenghtening plasticard.

Postby peak experience » Wed May 14, 2014 10:47 am

very interesting thread. i build lots of factory, depot structures etc and often think about this problem. i've yet to find an answer that's adequate. with a building (apart from those that are open structures) at least it's possible to trick the eye into believing the walls are one asbestos/panel thick.

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Boxcar Willie
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Re: Strenghtening plasticard.

Postby Boxcar Willie » Wed May 14, 2014 11:02 am

I've come up with the notion os simply using a double thickness of the corrugated plasticard. A layer of polystyrene glue between the sheets should provide the extra strength when it sets hard.

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Bufferstop
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Re: Strenghtening plasticard.

Postby Bufferstop » Wed May 14, 2014 12:38 pm

:shock: Carbon Fibre lamination that's the Nerd's solution :roll: Seriously, if you want to make any number of these, Make a master for the panels. I haven't tried this but it would be in my list of possible ways to do it. You'd need to use some corrugated sheet and some filler to get the tapering flutes, then take a plaster cast of it (seems to me you'd need three types of panel, side, end and door). When the plaster cast is solid, grease it and start pressing in thin layers of fibrous paper or cloth soaked in PVA or resin. Finish by pressing the master into it to the rear to impress the shape. Let each harden then assemble with thin deep strengthening plastic sections in the joins. As the sides would be made up of separate sections I would make a top capping from a single piece hollow rectangle of thin plastic or even brass.
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outcastjack
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Re: Strenghtening plasticard.

Postby outcastjack » Fri May 16, 2014 10:12 am

Boxcar Willie wrote:I've come up with the notion os simply using a double thickness of the corrugated plasticard. A layer of polystyrene glue between the sheets should provide the extra strength when it sets hard.


that should work, I make a lot of stuff from 10 thou flat plasticard, and dispite a single thickness being as floppy as paper, laminating two pieces give more than adequate stiffness for trucks
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