Stone Casting - sources of polystyrene

[puffernutter]

As some of you may know, I breed and show Clumber Spaniels. I'm also involved on the committee of the UK Clumber Spaniel Club and I organise an annual "Clumberfest" near Trowbridge. I'm always looking for novel ways of raising money for the club and as we have a stone masons just down the road (who sells or sorts of different cast objects) I mused about having stone clumbers cast.

It's along and complicated (and expensive) story, but I now have a mould for a life size Clumber in my garage. On Saturday we filled it with a sand/cement mixture for the first time and we'll see what the quality is like Wednesday evening (exciting!)

However, my problem is that this took 4 bags of sand and 1 bag of cement (125kg in total) so that is not a lightweight casting, turning it out is going to be fun to say the least. So it would seem a plan to partially fill the centre of the mould with polystyrene to take up space that would otherwise be occupied by the sand/cement and try and reduce the cost of the filler and the main reason, reduce the weight.

So apart from sharing my latest daft idea with you (pictures below) what is a good source of polystyrene. I've seen sheets in builders merchants, but what I'd ideally like is a square or rectangular section of say 150 x 150mm or 150 x 200mm that I don't have to make up out of thinner sheets.

Any sources come to mind?

The "original" - Henry (Whissgig Daddy Cool)

The clay model (almost complete), used to create the rubber used for moulding, but gets destroyed in the process!

The mould - waiting to be filled

The filled mould waiting (Wednesday 5th July!) to be turned out!

 

[Paul.]

You could try these, http://www.dssmith-foamproducts.com/contact/ they are local to me and I have done work for them in the past but I don't know if they sell small quantities though,

 

[Barking Mat]

I've got 60m2 of 100mm thick waiting to be floor insulation. I think it exists in plaques up to 200mm thick. Builders yards won't have offcuts as its sold by the plaque. Building site? Your local recycling center? You don't need much by the look of it. Its really not expensive.

Can't you 3d scan the beautiful clay model and then reproduce it on a 3 d printer to make the lost jobee? Just dreaming.

 

[Dieselman 63]

Yep, building sites are a good source - anything under a full sheet can't be sold back to the yard so they just get dumped then binned at the end of the job. I got tonnes of stuff working on one recently, timber, roofing iron etc, all scrap but nothing wrong with it.

 

[Barking Mat]

I know a bloke who works for a company who solely goes round sites picking up leftovers to dispose of them for the building companies. Nice job eh?

 

[WorkshopChris]

Could you fill a shoe box or similar with expanding foam and trim to size?

 

[Parm]

Could you fill a shoe box or similar with expanding foam and trim to size?

Probably the cheapest way

 

[captain-destructo]

does the plinth need to be that big?

keep an eye on every builders skip you drive past

 

[puffernutter]

I'm still experimenting. There doesn't need to be a plinth, so the next may be without and I'll compare the "look"

Cheers

Peter

 

[puffernutter]

does the plinth need to be that big?

keep an eye on every builders skip you drive past

Builder's skips are much less accessible than they ever were, I don't live near one or pass by or work on one, so not easy - but I will keep my eyes open when I'm walking Henry!

Cheers

Peter

 

[gaz1]

if your using foam then make sure the foam is way smaller to allow a good 3" thick concrete all around it

also to allow the mixture to come over the foam for the base of it so its all covered with 3" thick concrete all around this will make it alot lighter but give it a good thick area so frost dosnt crack it

 

[slim_boy_fat]

Could you fill a shoe box or similar with expanding foam and trim to size?

Beat me to it - I was going to suggest 'hard-packing' [i.e. tamping] a layer of sand inside the existing mould first, but looks like @gaz1 beat me to it too.

 

[puffernutter]

One option could be to do the plinth as an option and cast it separately. It would certainly be easier to move around!

Cheers

Peter

 

[slim_boy_fat]

It would certainly be easier to move around!

Thereby saving the thieves from having a hernia..........

 

[Pete.]

How are you going to hold the polystyrene core stationary in the mould? When it's used in formwork they usually fix it in place pretty well, and very often it still moves either from the concrete pour or from bouyancy.

 

[puffernutter]

Some more thoughts this morning was to try with Celotex (not too expensive to experiment with and available in a sensible size from Wickes). Was planning to create/sculpt the piece of polystyrene to size I can use (leaving enough concrete all around it and then place wires into the top to hold it. That will then be supported by a bearer over the top of the mould. I'd part fill the mould, insert the polystyrene, hold it in place through the wires and bearer over the top, complete the fill, let it start to go off and before I do the smoothing of the top surface (what will be the bottom) just pull the wires out. Hopefully the cast will have set enough to hold it in place.

Well that's the theory anyway!

Cheers

Peter

 

[I'm getting on a bit]

Maybe you could try this method using fast setting cement.
http://www.rutlandplastics.co.uk/plastics-moulding-methods/plastics-moulding-methods-roto/

You can control thickness this way, seen it on How It's Made

 

[gaz1]

another way i can think of is use perlite for the internal mix held in a bag or balloon with a 2" hole at the bottom

empty the perlite out leaves a cavity behind use the perlite again

 

[bigegg]

Perlite is about £20 for 100litres - if you substitute it for the gravel, it'll half the weight of the concrete.
It will also reduce the strength, but double the cement amount will counter that.
<edit gaz1 sort of beat me to it!>

 

[bigegg]

another way i can think of is use perlite for the internal mix held in a bag or balloon with a 2" hole at the bottom

empty the perlite out leaves a cavity behind use the perlite again

I wonder if a lost wax core would work?
Or just force a tapered, oiled block of wood in from the bottom.
Remove when the concrete has cured.