On Oct 2, 3:49*pm, 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

It sure would be easier if you could get a sample of the shape you
want, using that to cast a mould.

Re bending plastic, last time I did it I just dipped it in boiling
water. Works with some plastics - unfortunately I dont remember what
kind of plastic it was. Making a mould in thin air is going to be hard
to get just right.


NT