Consists of a chuck body and four contact arms. Designed to check ‘run-out’ or concentricity, straightness and alignment. Will indicate the position of a datum point on a component or fixture from the centre line of a machine spindle. Suitable for use on drill presses, lathes, milling machines, borers etc. \n\nChuck Body: \nHeld in the spindle using a suitable drill chuck or collet chuck (fig 1). The contact arms are retained in position using the knurled collar which lightly clamps the ball joint inside the body. Arms may be exchanged without the need to remove the body from the machine spindle. \n\nUniversal Indicator Holder \nThe detachable end will allow clamping with 2 and 3 piece dovetail clamping assemblies and when removed will fit standard 1/4” side clamp. This uses the spindle centre line to align component bores or spigots, check the flatness or squareness of workpieces or fixturing and check run-out of components. The spindle should only be rotated manually to avoid damaging the dial test indicator (fig 1).\n\nNeedle Point\nTo lightly mark out lines and positions on a component as a guide to subsequent operations, using the machine’s dials or digital read-out to position the scriber point (not illustrated). \n\nPosition the contact arm in line, but slightly away from the surface to be aligned. When finding the surface of a diameter, the ‘Disc' must be positioned as near to the centre of that diameter as possible. Run the spindle between 200 and 500 revs/min. The table or spindle is then moved slowly, to bring the contact arm closer to the surface to be aligned. The contact arm will tap lightly against the surface (fig 2) the movement of the arm will become less and less the nearer the datum point gets to the spindle centre line (fig 3). When the arm stops spinning in a straight line and starts to 'jump', this indicates the datum point (fig 4): \n1/2 contact dia + Edge = Centre \n1/2 contact dia - Centre = Edge\n\nBall Contact .250”\nUsed to find a datum point .125” ± .0005” away from a flat surface.\n\nDisc Contact .100” \nUsed to find a datum point .050” ± .0005” away from a convex surface.\n\nContents: Chuck Body, Universal Indicator Holder, Needle Point, Ball Contact, Disc Contact.