Stone Cropping
For cropping or guillotining stone we use a hydraulically powered Steinex 120 tonne stone splitter with a 5 metre conveyor. This allows us to process the large pieces of rock from the quarry into usable walling stone.
Our 8 tonne excavator then breaks the boulders with a hydraulic breaker into sizes that the boys can manoeuvre on the Steinex.
When the rock comes from the quarry it usually arrives in large boulders up to 200 kg each which is unusable in normal walling applications.
The stone is then loaded into a conveyor that is controlled by the Steinex operator. Each piece is then selected by hand and turned to obtain the best piece of walling stone.
The cropper head has individual teeth that adjust to the shape of the stone. This gives a far cleaner and straighter cut than a conventional straight blade. Below is BMQ 100-150mm cropped random building stone. The cropping or guillotined stone will have at least one usable face, this may be a cropped face or a natural face.
A typical bag of BMQ random walling stone. 
150mm Random BMQ used in conjunction with surecav to form a cavity
All our stone is cropped to 150mm bed width (footing width). It is a maximum of 150mm and a minimum of 100mm, therefore it is not suitable for building a free standing or cavity wall and will need a backing block or surecav.
The 150mm measurement does not relate to the height or the length of the stone; they are both completely random.