Yes, had a nibble. was 75 cts in 06[stuck drill}.r$cov$r$d...

Yes, had a nibble. was 75 cts in 06[stuck drill}.r$cov$r$d **************read comments about expansion down the hole; weight of casing [good thinking] etc.IMHO with the casing in place; concrete is poured down the borehole; bonding the casing to the surrounding borehole.Now all things have a degree of elasticity and compressibility and different expansion rates;Imagine a 1 metre bar {reppresenting the casing} within a slab of concrete;{the latter representing concrete and surrounding mass of earth],and if the slab is heated to 300*C the slab{earth]; will expand and so will the bar [casing].[a greater expansion rate of iron is looked after by its compressibility and the elastisity of the concrete,] and there is no relative movement of the casing and the surround earth. a hump in the general area mabie. .