Listen to Geordie as he be the king of coring! :iagree:
Yep .... back in the early '70s when it was a specialised subject with only specialised companies doing it - one of which I worked for - I made a core drill 3 feet in diameter and the rig to drive it.
The rig was powered by compressed air and it together with a diesel driven compressor was mounted on the back of an ex-army truck. A water bowser was required to keep the drill cool and it stood alongside the rig.
The job was for the (then) London Airport who wanted a serias of 3 feet dianeter holes in their runways and we tested the rig in our works yard one morning before the gaffer arrived.
I took great delight in drilling the hole right where he parked his car. He arrived sometime after 9am & was not best pleased.
I tell ye ... some folk just have no sense of humour!
Then there was the Eldon Square shopping Centre which was under construction at the time. The flloors were cast reinforced concrete and then the holes were sawn through for the escalators using Floor Saws which are circular saws with 2 or 3 foot dia. blades mounted on a glorified go-kart. We made the whole thing incuding the blades. Nowadays you just buy them.
Another nice little job was to make the core drills, extension shafts (I forget how many but they were each 10 feet long) and the rig to drill a series of 10" diameter holes throught this:
The drilling & cutting of reinforced concrete has come a long way since then & I have to take my hat off to the blaggers who did that Hatton Garden Safe Deposit heist.
That drilling was just pure quality!!
