How to make a sundial artwork - casting the concrete post tutorial

The final big bit of 'making' with these sundials is casting the vertical support for the horizontal dial to sit on. Making concrete is actually a very simple process, by mixing cement, sand, chippings and water I can pour the mixture into a pvc downpipe to create a solid post.
By inserting a metal threaded rod into the centre of the drainpipe mould, I can make sure the concrete itself is supported but also allows me to slot the post into the carved oak base. Then at the top of the post, I can insert a few smaller threaded rods so that the stainless steel sundial plate is supported.
The only issue for me is waiting long enough to make sure its all totally cured...