Marking-off and Drilling a Cylinder

Drillings of Circular Holes In any mechanical parts, we often drill holes on a circular pattern on the face of a cylindrical as shown in Figure 1. Figures 2 to 7 shows the procedure of a marking-off and drilling on a typical part.

Fig.1, Part Drawing

Fig.2, Marking the Center Lines on the Work Piece The work piece is set on a square block and securely fastened in the "vee" section. Find the center of the work piece and scribe a vertical a line across the face. Care must be taken to find the exact center otherwise the desired accuracy cannot be obtained.

Fig.3, Markings of Center Lines (continued) Turn the square block 90 degrees and mark the line across the face as it step one to achieve the intersecting line.

Fig.4, Marking with a Center Punch Find the center of each line at the exact location to be drilled and using a center punch and hammer, lightly mark the drilling position. Check the dimensions and if they are correct, re-punch the marks but this time using a bit more force.

Fig.5, Marked-off Material The marking-off process is complete and the work piece is ready to be drilled.

Fig.6, Processing of a Drilling Machine Secure the work piece in the drilling machine vice and drill the holes.

Fig.7, Completed Part The finished piece.

Using V-shaped Block A V-shaped block as shown in Figures 8 and 9 is used for the marking-off of a cylindrical part. Note, the vee block shown does not have a securing clamp so it is not as convenient to use as one with a clamp. Fig.8, V-shaped Block Fig.9, Setting of a part on the Block

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