Multiple Start Threading Example

Classic Control - Lathe Operator's Manual

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Multiple threads can be cut by changing the start point for each threading cycle.

The previous example has been modified to now create a multiple start thread.

To calculate the additional start points the feed F0.0714 (Pitch) is multiplied by the number of start points (3) to give .0714 * 3 = .2142. This is the new feed rate F0.2142 (lead).

The pitch (0.0714) is added to the initial Z-axis start point (N2) in order to calculate the next start point (N5).

Add the same amount again to the previous start point (N5) to calculate the next start point (N7).

% o60762 (G76 MULTI START THREAD CYCLES) ; (G54 X0 is at the center of rotation) ; (Z0 is on the face of the part) ; (T1 is an OD thread tool) ; (BEGIN PREPARATION BLOCKS) ; T101 (Select tool and offset 1) ; G00 G18 G20 G40 G80 G99 (Safe startup) ; G50 S1000 (Limit spindle to 1000 RPM) ; G97 S400 M03 (CSS off, spindle on CW) ; G00 G54 X1.1 Z0.5 (Rapid to clear position) ; M08 (Coolant on) ; (BEGIN CUTTING BLOCKS) ; G76 X.913 Z-.850 K.042 D.0115 F.2142 (1st cycle) ; G00 X1.100 Z.5714 (Z0.5 + Z0.0714) ; G76 X.913 Z-.850 K.042 D.0115 F.2142 (2nd cycle) ; G00 X1.100 Z.6428 (Z0.5714 + Z0.0714) ; G76 X.913 Z-.850 K.042 D.0115 F.2142 (3rd Cycle) ; (BEGIN COMPLETION BLOCKS) ; G00 G53 X0 M09 (X home, coolant off) ; G53 Z0 M05 (Z home, spindle off) ; M30 (End program) ; %

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