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**wonwinglo** · 18-07-2004

One of the most useful and attractive features of perspex is the ease that it can be shaped,when heated to 140 degrees C.it becomes quite pliable.
The easiest and most straightforward way of heating is to immerse it in boiling water.
But before you do this dont forget to remove the protective masking first.You can do this by washing the sheet in warm water,this removes all of the gelatine coating a the same time.Now,before boiling the water be sure to get all of your jigs and formers ready.These are the things that shape the perspex and you will probably find a lot of these items around the house,you can put metal spoons to good use for example,strips of perspex can be easily wound around rods,jars etc.
One tip is to never boil the perspex,always boil the water first and add the perspex when the water is just off the boil,the time the perspex is left in the water depends on the thickness of the sheet but generally it is between two and ten minutes,it is ready for use when sufficently pliable to bend by itself when lifted out of the water.
Take care when handling and use tongues or a similar tool,taking care not to mark or dent it while it is still soft.Wipe off all of the moisture and place the plastic in or around the shaping former.
To stick perspex requires special cement called perspex cement,however if you have difficulty in finding any buy a bottle of acetone from the chemists and soak shavings or small broken pieces of perspex of perpex into it for 48 hours,this makes a very acceptable adhesive.
Make sure that the product you are working with is proper perspex and not acrylic sheet an entirely different material.

OOLILISSIMA · 21-12-2006

I've just registered, and I'm really pleased to find such a great forum!!

Barry, I'm planning to make a 1/3 scale canopy for an Auster A5. The sheet before moulding will be something like 1100x370mm, and the canopy shape is complex. I'm therefore thinking that the need to keep the material soft for long enough to work it around all of the plug former might make the boiling water technique difficult for me.

I wonder if you have any experience of anything of this sort of size, and whether you think that an electric paint stripper (with controllable temperature, of course) would work.

OOLILISSIMA · 21-12-2006

Another quick one if I can, please Barry. You seem to imply that acrylic sheet other than Perspex is not suitable. Could you possibly say in what way you mean, please?

alan2525 · 21-12-2006

Isn't Perspex a brand name for Arcylic?

You can also get two different grades of Acrylic sheet, drawn or cast Acrylic. Cast sheet is best for forming.

OOLILISSIMA · 21-12-2006

Thanks Alan. That's what I had understood, but i'm new to this and I'd like to know the differences before I jump in with both feet.

While writing, I should correct my first post above. I meant that I am planning a model of an Auster Mk 5.

**wonwinglo** · 21-12-2006

Paul first of all forget moulding a canopy with such a deep draw out of sheet employing this method,it simply will not work,what you need to do is to vacform the canopy,best to make up the plug from block balsa or even softwood,take or send it to a specialist who will run you off as many as you wish.
True Perspex is no longer made and my notes are out of date,modern clear commercial sheet is called Acrylic,it has a distinctive sweet smell to it when moulded and used a lot in the double glazing industry,persex was used originally in making full sized aircraft canopies as it was good for getting things optically perfect,its use can be quite critical as regards working temperature.
Also do not forget to slightly undersize your plug to allow for the thickness of the clear sheet.
There are also many other clear sheet materials with obscure names,some have plasticizers added others without,check out craft suppliers such as Opitec who may be able to assist with vac forming supplies,vac forming is much preferred for anything with a deep draw to it.

alan2525 · 21-12-2006

I've got access to a vac forming machine if you have a former I'd be happy to vac form some.

OOLILISSIMA · 21-12-2006

Barry, many thanks for your advice.

Alan, that's very helpful. Could I contact you again when I get a plug made? It might be a month or three, as I am in the early stages of design and building, although I'll give making the plug as much priority as possible in view of your kind offer.

alan2525 · 22-12-2006

Do you have any images of the Auster A5? I could only find images of an A3 online. Would the canopy be vacuum formed in sections?

OOLILISSIMA · 22-12-2006

Alan, it's actually an Auster Mk 5 (or Mk V). This is the military version of the Auster J/1 Autocrat. The only difference in the superstructures of the two is the length of the canopy. The Mk 5 canopy extends back past the trailing edge to facilitate military observation duties. I am not familiar with all of the Auster planes; maybe there is also an A5, although I tend to think it should be Mk 5.

So far, I have only a few images from the net. I haven't spent much time looking for them, so you'll easily overtake my efforts by "Googling" these Auster Mks in some appropriate phrases.

I have been and photographed a real Mk 5, which is the property of the Leicestershire Museum Service. If they have no objection, I'll let you have copies, either through the forum or to you individually. If you're wanting to scratch build a model, their volunteer Auster specialist is very helpful with drawings and advice. He is also very knowledgeable. He can provide extracts of your choice from Auster's factory drawings. They also have very good three-view and other modeller-orientated drawings, prepared a few years ago by an enthusiast. You'll find the necessary contact details on the Leicestershire, Leicester and Rutland County Records office web site.