▲ the pitch angle should be determined through calculation or by using the chart below. ▲ the standard threading holder is supplied with a 1.5 ° inclined insert seat and a shim without angular correction. Hence the Tool holders are delivered with an angle of inclination β of 1.5 °. Calculating the helix angle β: For trapezium: 20 = constant β = Helix angle (°) TP = Pitch (mm) DMIN = Nominal diameter (mm) From the flank Ø in the diagram, a line is drawn vertically upwards until it intersects with the line of the pitch of the thread to be produced. In the color-coded region in which it is now, a horizontal line to the edge of the chart indicates the appropriate factor. 20 x TP 15 x TP DMIN DMIN 20 x 1,5 mm 24 mm β = Important Information about Standard Shims Method 2: Diagram Method 1: Calculation Without the appropriate correction of the helix angle, the following may occur 1 2 3 4 5 6 7 8 9 11 10 12 2.5 3 3.5 4 4.5 5 6 7 9 11 14 18 24 β = 0° 2.25 mm 1 2 3 4 5 6 7 8 9 11 10 12 2.5 3 3.5 4 4.5 5 6 7 9 11 14 18 24 2.25 0 50 100 150 200 Pitch TP Feed Towards Chuck Feed Towards Tailstock Flank-Ø (mm) TPI β = 2,5° β = 1,5° β = 0,5° β = - 0,5° β = - 1,5° β = 3,5° β = 4,5° β 1,5° Standard Shim Tool holder Pitch angle ▲ the profile will be distorted. ▲ insufficient clearance angle. ▲ the tool life of the insert is greatly reduced. β = Pitch TP Example calculation External thread M24 x 1.5 Feed towards chuck DMIN = Nominal Ø: M24 = 24 mm TP = Pitch: 1.5 mm calculated pitch angle β value Correction angle α 0,0°–0,49° -1,5° 0,5°–0,99° -1° 1,0°–1,99° 0° 2,0°–2,99° +1° 3,0°–3,99° +2° 4,0°–4,99° +3° 0,0°–(-0,49°) -2° -0,5°–(-1,5°) -3° β = 1,25° Separate - Toolholder Separate - Toolholder Thread turning Technical Information
