tonyjeffs wrote:
Building a wall, making 8"x8"x9" ornamental exposed aggregate concrete
blocks.

Well I've finished my flat-sided tapered blocks and now I'm on to the
copings.

They are bell shaped, with quite tight 1.5" dia curves. The mould will
be to take 3 blocks, approx 8x8x9 each.

Any thoughts on how I can make the curve? I can use 3 existing blocks
in line as a guide.

I tried wrapping them in polythene, boxing them in, and injecting
expanding yellow foam, but it didn't match the contours tightly.

I tried soaking hardboard, bending it when soft, and letting it dry,
but was surprised how water and bend resistant hardboard is.

I'm trying papier mache. If it works, it mightn't last very long with
the wet concrete.

I thought about getting a sheet of thin stiff plastic, heating it,
fitting it, and letting it set into the correct shape. But how would
I heat it until it is soft? boiling water wouldn't be hot enough, and
a blow-lamp would be too unsubtle.

Or maybe any of those approaches'd work if I did 'em more carefully?

Any suggestions welcome.

Thanx
Tony

PS, this group has just cost me a fortune ;-)
After reading here about SDS drills - they sound a brilliant addidion
- I am absolutely itching to buy a decent cordless one. Not cheap!

I recently bought an AKG 12v cordless screwdriver. Best tool I ever
bought. Brilliant. Recommended
If the curve is in one direction only, look in B&Q for bendy MDF. It is
about 4mm thick and kerfed on one side to bend to a reasonable radius,
but I suspect not tight enough for what you want. It would be easy to
waterproof and you may be able to add more cuts to increase the bend
radius.

Malcolm