Light Aircraft Association

Does anyone know where I can source some blocks/sheets of styrofoam? I need this to form into an internal moul so many products wont work due to the limits of shaping them. Any help would be welcome.

Adrian

A Morris wrote:Does anyone know where I can source some blocks/sheets of styrofoam? I need this to form into an internal moul so many products wont work due to the limits of shaping them. Any help would be welcome.

Adrian

Moul should be mould !

Adrian
Custompac in Castleford or Millers in Leeds.
A bit of Googling will find their numbers....
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Also try Sheffield Insulations - http://www.sheffins.co.uk/contact.asp They have branches all over the UK. Put "styrofoam" in the product search box and there's several Dow products listed.

Good styrofoam is expensive and worth it /necessary only for permanent embedded aircaft parts /structure.

Bear in mind that for moulds virtually any old styrofoam/white insulation foam will do - the latter is used a lot in packing* and you can laminate /pin together thinner slabs with cocktail sticks etc to make up a thick piece for hot wire cutting & sanding to shape.

*Superstore skips are a good source

Steve Brown wrote:Good styrofoam is expensive and worth it /necessary only for permanent embedded aircaft parts /structure.

Bear in mind that for moulds virtually any old styrofoam/white insulation foam will do - the latter is used a lot in packing* and you can laminate /pin together thinner slabs with cocktail sticks etc to make up a thick piece for hot wire cutting & sanding to shape.

*Superstore skips are a good source

Only trouble is the finish and most polystyrene melts in contact with glass fibre resin.

Styro foam melts in both petrol (useful sometimes to dissolve a complex male plug mould) and polyester resin ( the stinky stuff as found in Isopon / car body repair kits).

If you want to use polyester (cheaper & quick to go off (too quick sometimes) ) then carvable urethane or pvc foam is used but these must not be hotwired (gives off cyanide gas)

To make hot wireable styro moulds, you need to use epoxy such as the West system which does not dissolve styro - or at least coat the final shaped styro male mould with a glass layer & epoxy before laying polyester over it

If you are faced with having to buy a minimum quantity of Styrofoam that is far more than you need, try contacting Europa Aircraft (01751 431773) who will probably be happy to sell you only what you need and cut it into convenient sizes for you on their hot wire cutting machine, if you ask nicely.

Andy Draper

http://shop.ebay.co.uk/?_from=R40&_trks ... Categories


Please tell me people aren't still using polyester for glass layups .......!

West is Best !

Cheap chopped strand mat glass with polyester resin is excellent for mould making - sets quickly & it seems a waste to use good epoxy for this - especially on larger moulds like cowlings etc

Oh but the quality luvvy - think about the quality

Having used West for 10 years, I wouldn't go back to polyester. The longer open time allows better use of resin - less - more options for finish - peel ply - lighter product, use of BID cloth gives great moulding and strength etc etc.

But there are many ways to skin the cat.

If you are only making a mould, I can see the potential benefit of polyester but for finished items - epoxy rules !

I agree - polyester (resin or filler) is total rubbish as a material for any actual aircraft product. Woven cloth, epoxy resin, epoxy based fillers & peel ply produce beautiful light parts.

Polyester also absorbs moisture so the finish falls off after a few years.

Polyester moulds made with a good gel coat can produce superb epoxy parts.

When I used to layup polyester on styrofoam, I used to seal the plug with PVA glue. This was for RC models and so quite small parts by comparison with GA.
However. You wont find a better explanation than that in Tony Bingelis's Sportplane Construction Techniques. ( Available from the LAA ! )