The Imac bevelling machines can carry out bevels in preparation of the welding on linear sheets of different materials having a thickness from 6 up to 45 mm in a very quick, noiseless and cheap way avoiding the production of smokes and dusts. The bevelling angle can vary from 22° to 60° by simply replacing the roller group and in the case of the variable angle model, by simply changing the working angle. The fixed angle bevelling machine models (CB18 and CB25) can carry out pre-defined bevels (22°; 30°; 45°; 60°) They can be equipped with a cart used for moving the machine self and for supporting it during the working of long and heavy pieces since the machine can be hooked horizontally to the piece that is being worked. The variable angle model can be set to produce bevels of various angles by simply adjusting the sheet feeder roller as required, from a minimum of 22.5° to a maximum of 52.5°