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Lathe cycles

Syntax, parameters and diagram for each cycle

G71

Longitudinal roughing

Removes material parallel to the Z axis in several automatic passes.

When to use: Cylindrical parts where most stock is removed along Z: shafts, bushings, rods.

passes paralelos ao eixo Z
Syntax
G71 U(depth) R(retract)
G71 P(start N) Q(end N) U(X stock) W(Z stock) F(feed)
Parameters
  • U (line 1) — depth of cut per pass, in radius
  • R — retract distance after each pass
  • P/Q — N of the first and last profile block
  • U (line 2) — X stock left for finishing
  • W — Z stock left for finishing
  • F — roughing feed rate
Example
G71 U2. R1.
G71 P100 Q200 U0.4 W0.1 F0.25
N100 G00 X20.
N110 G01 Z-30. F0.15
N200 X60.
G70

Finishing

Re-runs the P–Q profile in a single pass, using the F programmed in the profile.

When to use: Always after G71/G72/G73 to take out the stock left by roughing.

single pass on final profile
Syntax
G70 P(start N) Q(end N)
Parameters
  • P — N of the block where the profile starts
  • Q — N of the block where the profile ends
Example
G70 P100 Q200
G72

Facing roughing

Passes parallel to the X axis — stepped facing.

When to use: Flat parts with lots of stock on the face or deep radial profiles.

passes paralelos ao eixo X
Syntax
G72 W(depth) R(retract)
G72 P__ Q__ U__ W__ F__
Parameters
  • W (line 1) — depth per pass on Z
  • R — retract between passes
  • P/Q — profile boundaries
  • U/W (line 2) — X/Z stock for finishing
Example
G72 W1.5 R1.
G72 P100 Q200 U0.4 W0.1 F0.2
G73

Pattern repeating

Repeats the P–Q profile shifting it in X and Z until the final size is reached.

When to use: Pre-formed parts (forged, cast) — avoids cutting air.

perfil deslocado em X e Z
Syntax
G73 U(X shift) W(Z shift) R(number of passes)
G73 P__ Q__ U__ W__ F__
Parameters
  • U (line 1) — total X stock to remove (radius)
  • W (line 1) — total Z stock to remove
  • R — number of passes to the final profile
Example
G73 U3. W1. R3
G73 P100 Q200 U0.4 W0.1 F0.2
G74

Face peck drilling

Axial peck drilling: drills, retracts to break the chip, continues.

When to use: Deep center holes where the chip doesn't clear on its own.

fura → recua → fura
Syntax
G74 R(retract)
G74 Z(end) Q(peck depth) F__
Parameters
  • R — retract after each peck
  • Z — final hole position
  • Q — depth of each peck (in microns, no decimal)
Example
G74 R0.5
G74 Z-40. Q3000 F0.1
G75

Radial grooving

Cuts grooves in X with automatic chip breaking.

When to use: Grooves for locks, snap rings, thread relief.

canal radial com quebra-cavaco
Syntax
G75 R(retract)
G75 X__ Z__ P__ Q__ F__
Parameters
  • X — diameter at the groove bottom
  • Z — last axial position (if there is width)
  • P — peck depth in X
  • Q — Z shift between passes (width)
Example
G75 R0.5
G75 X28. Z-15. P2000 Q3000 F0.08
G76

Automatic threading

Threads in several passes with decreasing depth.

When to use: Metric, Whitworth, NPT threads — always in G97 (fixed RPM).

filete formado em passes
Syntax
G76 P(mm rr aa) Q(min. depth) R(finishing stock)
G76 X(bottom) Z(end) P(height) Q(1st pass) F(pitch)
Parameters
  • P (line 1) — mm = finishing passes, rr = chamfer, aa = insert angle
  • Q (line 1) — minimum depth per pass (µm)
  • R — finishing stock
  • X/Z — bottom diameter and thread length
  • P (line 2) — total thread height in µm
  • Q (line 2) — 1st pass depth in µm
  • F — thread pitch in mm
Example
G97 S1000 M03
G76 P020060 Q100 R0.02
G76 X28.16 Z-24. P920 Q200 F1.5