centre punch

British  

noun

1. a small steel tool with a conical tip used to punch a small indentation at the location of the centre of a hole to be drilled

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Example Sentences

He kept a toffee hammer and a centre punch in his car.

From The Guardian

This being done, point b of the tram is rested in the centre punch dot before referred to, and with the other end a line c is marked, a straight edge is then rested against the ends e e of the cross head, and a line d is marked on the guide bar, this line being exactly even or fair with the end e e of the cross head.

From Project Gutenberg

But as soon as the crank pin has passed its dead centre, the cross head will begin to move to the right, and as soon as the end e e comes again exactly in line with the line d marked on the guide bar, we must stop moving the wheel, and again resting the point b of the tram in the centre punch mark before mentioned, we move its other end so as to mark a second line, which will be the line or arc f.

From Project Gutenberg

The next thing to do is to mark a fine centre punch dot, where c and f cross the arc or line a, and then find the point g midway between f and c, and mark a fine centre punch mark there.

From Project Gutenberg

This being done, we must move the wheel back into the position it occupies in the figure, and then slowly move it in the direction of the arrow, until with the end b of the tram resting in the centre punch dot, the other end of the tram will fall dead into the centre punch dot at g, at which time the crank pin will be exactly on the dead centre.

From Project Gutenberg