The machine comprises a shield (1) and a mechanism with a boom (4) mounted on two vertical frames, one inside the other, the outer one (9) being fixed, while the inner one (10) swivels in it on a first vertical or horizontal axis. The boom pivots on the inner frame about a second axis at right angles to the first one. The outer frame has preferably a cam whose profile corresponds to the section of the tunnel or gallery to be driven, in conjunction with which there works a follower on the boom, so taht the latte cannot cut outside the desired tunnel outline. The outer frame can be arranged to slide on the tubular shield, whose shape and dimensions correspond to the tunnel to be driven, and travels along it as work advances.
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