eureka moment

[Tim Lamb]

First for the year:-(

New sandpit constructed for the grandchildren..... yes, I did try it out! Why doesn't play pit sand come out of moulds cleanly like damp sea sand?

Management is insisting that it must have a cover. Cats, Foxes, falling leaves etc. At around 2mx 1.5m not ideal for plywood offcuts.

Co-incidentally some left over tubular metal garden cloche ends match the 1.5m dimension and there are lots of 12mm o/d steel tubes more than

2m long. I don't have tig or mig welding tackle.

The cloche design used plastic spigots secured to the end frames which plug in to larger diameter tubing than I have.

The eureka idea is to plug the tube ends with some hot melt (glue gun) glue, grind the ends to match the cloche end, drill a hole to take a stainless woodscrew......:-)

[stuart noble]

If the kids use it more than once I'll be surprised, whereas a bag of sand with plastic pots.....

[Andrew Mawson]

We had about 40 kids with their parents here yesterday at a wedding reception for my daughter. A pile of hay bales kept them amused from noon until late evening - not a single tantrum or argument - quite amazing and relatively easy to arrange. Mind you the clear up is going to be a bit of an issue !!!!!!!

Andrew

[Tim Lamb]

AOL:-)

Straw is cheaper! Mind, dad and youngest are hay fever sufferers.

I take Stuart's point about usage but, if nothing else, it means I don't have to struggle (and can sell!) carrying the portable one out of the garage!

[Andrew Mawson]

But daughter insisted on hay as it's softer. Straw I could use for pig bedding, I don't need hay until next winter for the sheep and it's debatable what state it'll be in then - even the 40 or so full bales I managed to recover before the rain :(

Andrew

[Brian-Gaff]

Sandpits can be a real pain to keep animals out of of course, but one has to be sure the device for covering them is not itself dangerous.

as for making the right constituancy, there was, believe it or not a study done about the correct types of sand and mixture of water, to make good sandcastles as it was needed for a comercial project i seem to recall. the type of sand is very important.

I just wish I could remember what I was looking for when i found it by accident. Brian

[Chris French]

In message , Tim Lamb writes

Our kids used to love the sandpit when they were younger.

And I had one as a kid. Quite deep IIRC, sunk in the ground lined and floored with paving slabs. We spent ages playing in their digging tunnels for toy cars etc. playing with toy soldiers

[F Murtz]

Brickies sand?

[Tim Lamb]

In message , Brian-Gaff writes

I'm thinking of a light steel frame covered in waterproof woven plastic sheet.

Play pit sand is claimed to be *rounded* rather than *sharp* for safety reasons and also much finer than sea sand. The appearance is similar to moulding sand used in metal casting.

I tried whacking the moulds with a metal trowel but still failed to get a clean release.

Oh well. Another of life's imponderables:-)

[Robin]

Possibly one of many press reports in 2012 of paper by Dutch physicists in Nature's Scientific Reports. Synopsis:

"Just a bit of water enables one to turn a pile of dry sand into a spectacular sandcastle. Too much water however will destabilize the material, as is seen in landslides. Here we investigated the stability of wet sand columns to account for the maximum height of sandcastles. We find that the columns become unstable to elastic buckling under their own weight. This allows to account for the maximum height of the sand column; it is found to increase as the 2/3 power of the base radius of the column. Measuring the elastic modulus of the wet sand, we find that the optimum strength is achieved at a very low liquid volume fraction of about 1%. Knowing the modulus we can quantitatively account for the measured sandcastle heights."

I remember discussing at the time the possibility of a bid for EU funding to establish a consistent set of measurements and ratings for beaches across all member States. But we concluded the German's would be bound to get there first :(

[Tim Lamb]

In message , Robin writes

After Friday's rain this was certainly very wet sand. Not to the level of self slumping though.

I wonder if the granule shape leads to a higher contact area and more

*sticksion*.

:-)

[The Natural Philosopher]

stiction, IIRC...;-)