Early miners at Lightning Ridge would dig narrow drives into the claystone level from the bottom of the shaft, looking for signs of opal. Until the 1960s, drives were excavated manually.
The clay, first dug out with a handpick, was then shovelled into a drum and carted along the ‘drive’ (or tunnel) to the shaft.
John McCabe, 1979
…Tom and I were busy sinking shafts, then driving tunnels in the opal dirt, below the sandstone, toiling hard for that elusive opal. While thus driving in opal dirt any blow of the pick might unearth a stone.
Ion Idriess, 1940
Power Tools and Lighting
In the 1960s many miners purchased electric generators for lights and compressors to operate air jackhammers and other power tools. These tools allowed miners to knock down the clay at the face of the drive more quickly. Small wheelbarrows or carts called rickshaws were used to move the clay to a bucket at the bottom of the shaft, ready for hoisting.
Miners began using electric lighting for illumination underground, replacing candles and fuel lamps.
Our mine [now the Walk In Mine] was the first to have electric lights and compressed air jackhammers. My father bought lots of 110 volt lighting kits, which were from US Army surplus, and sold these to other miners.
David Randell, 2013
The first diggers made at Nexo Engineering in the late 1970s went through a long phase of testing and redesign to improve performance and reliability.
To speed production up down below, I bought a 1530 Case bobcat loader, and a little D100 Case backhoe that I altered and fitted to the bobcat to use as a digger. … As small as it was, it proved a great success, and within a short time, Knud Nexo had designed one without the need of a bobcat or other machinery: a major breakthrough for the miners of Lightning Ridge.
Gary Stone, 2004
I had been testing some ideas for an underground digger with a couple of prototypes, when in 1977, I decided to build one for myself. I knew that Gary Stone had attached a small backhoe to the back of a bobcat and was using it to dig with, and invited him down to have a look. He went down first and I was still on the ladder, when he started coming up and I said to him: “I thought you were going to have a look at the machine?” and he said “I have. I want one.”
Knud Nexo, 2003
The first diggers were air powered; this was inefficient because the airlines down the shaft and along the drive were too long, and the linkages were different to those on a backhoe. Knud changed the design to use hydraulics which were more efficient. Knud made a heavier and stronger digger and told me to test it and try to break it. He made hundreds of diggers, they were very successful and many people copied them – he never took out a patent.
Wolfgang Johansson, 2013
Pillars and Props
In productive areas, miners may need to widen the face of a drive or to create larger spaces in order to remove more of the opal level. To support the roof, they choose to leave pillars of claystone between the drives, or to install props. Most props used are logs cut from cypress pine, standing on a base plate and with a cap and wedges above to hold the prop firmly in place.
The claystone has varying hardness and joints that can weaken it. In deeper mines, the claystone level is usually soft and it will move under pressure. The idea [of propping] is to delay the onset of roof collapse.
John McCabe, 2013