Concrete moulds

[spoiltbrat]

Hi i,m lokking to make concrete moulds similar to this one below does anyone have any ideas on how to punch out or fit cut metal spheres to get a rough idea or does anyone think i could do the same with box section and get the same end results all help and tips welcomed i,m going to make six of these as i need 150 blocks to finish off my banking around my home

 

[cumbriasteve]

You can buy hollow spheres from most of the ornamental steel suppliers, they would give you the 'dome' shapes for the mould.
I guess you know you would ideally want a vibrating table to settle the mix properly, I did a bit of casting years ago and was not very good because I just poured, tamped down and left without vibrating

 

[Welderpaul]

Flat plate with the holes profilled out, buy spheres if the size suits, or get them spun. Flat bar stiffeners welded in. Thats how i'd do it anyway.

 

[outofthefire]

My ex father in law used to do a bit of casting and he had reasonable results vibrating the board the mold was on with an air chisel.

It'll be a slow process making 150 blocks though you'll need to leave the blocks a day to go off then ideally at least 7 days to cure. When you take into account materials and your time plus the element of doubt of wether you will be able to reproduce them to a decent standard wouldn't it be easier and cheaper to buy them, or use foundation blocks and cement its not hard to wall them.

 

[madkayaker]

could you make the turrets square with box to make it easier?

 

[Nomolos]

What about ball floats, nice and cheap and would leave a good finish

 

[spoiltbrat]

hi i have thought about 100mm spheres and have actually bought them , then i thought100 mm box section , i will use a concrete poker to ensure i can get most of the air out i have looked at buying but the price for the concete blocks and delivery is really expensive hence the reason for looking at diy i know its going to take ages but i can do them at different stages over the next 5 years as it will be a long term project , due to the strength of the flowing water a normal wall is not feesable or id immagine safe , thanks for all the info and help i have priced up the steel and it works out at approx 200 a mould rather than 1500 x vat from a cetrain supplier

 

[gerrymoore]

Hiya...dead easy and cheap...make the moulds out of fibreglass using clay or wooden plugs. I used to make garden statues this way and it worked great with a little release oil and tapping the mould with a mallet to get rid of the air.

I'm just returning to live in the UK after 10 years in Spain...writing this in a bar in Santander waiting for the ferry....will post some pics in a few days when we're settled in and have an internet connection....fingers' x'dd ...can,t wait to get back to a land where I can talk to people...in ENGLISH!!!!!

 

[derekm]

these spheres just provide a molded location lug and skt
replace with bit of steel bar in the tops and plastic tube in the bottom

 

[outofthefire]

What about using Gabions there great for holding back embankments and would allow water to filter through

 

[chunkolini]

I was going to suggest gabions, beat me to it.
making the giant lego bricks looks like a job that could easily go wrong with the numbers involved.

Chunko'.

 

[derekm]

even simpler idea: cast 2 or more large holes (110mm waste pipe as the form) vertically in each block. As you stack the blocks fill the holes with coarse gravel and/or reeinforcing rod and/or concrete (note concrete can set underwater). where the holes for each level overlap you will get a strong interlocking joint.
You could even cast concrete pins

 

[spoiltbrat]

Hi thanks for all the replies i dont want to use gabions as the grass and weeds and all the other rubish will still grow and collect around the banking