Machine-rosebits are represented by Fig. 841. It will be seen that the cylindrical part of the tool is provided with long narrow grooves, termed flutes. These are three in number, and are smoothly formed, to allow the oil or water applied to the tool while cutting to flow easily downwards to the cutting edges, and take with it all shavings that enter the flutes. These grooves also diminish the amount of bearing surface of the cylindrical part, and therefore lessen the amount of friction which would be incurred without them. Of the three grooves one is shown by the two lines in the Figure. Rosebits are used for smoothly finishing holes in objects of all classes, whether made of gun-metal, iron, or steel.