G50 and G51 Scaling Mode

Overview

• The shape defined by a part program can be enlarged or reduced according to a required scale.

Command Format

• Syntax: G51 X.. Y.. Z.. I... J... K... P...
  
  
• X.. Y.. Z.. [opt] - Center of Scaling
  
• The center of scaling is defined by X, Y, and Z (absolute position in Local Coordinate System)
• If XYZ values are not provided, scaling origin will be at the Local Coordinate System origin point (0, 0, 0).

• I... J... K... -Scaling with different ratios per axis
  • I.. - Scaling along X axis
  • J.. - Scaling along Y axis
  • K.. - Scaling along Z axis
  • P... - Scaling with even ratio along all 3 axes
  • G51 P2.0 ← Twice the size
  • G51 P0.5 ← Half the size

• Negative scaling values
• Negative values mirrors the part

• Syntax: G50

• Cancels scaling if active

Details ¶

• If there are P and I J K scaling values specified in the same line, the P argument takes priority and I J K will be ignored.
• If any of the scaling values are 0 = an error will be generated.
• Does not scale the feed rate
• Only scales the XYZ positions at most
• E position will be scaled by the highest scaling ratio (if using I J K) or the same as the P ratio
• A,B,C,U,V,W will be scaled the same as the E axis
• Effects on offsets
• Doesn’t scale tool offsets or tool compensations
• Does not scale coordinate offsets
• Does not scale rotational offsets or degrees
• G02/G03 arc behavior
• requires scaling to be applied uniformly to the currently active plane (G17/18/19)
• For example, if Arc is on a plane XY, I and J scaling values have to be identical (can be negative). If the arc is a helix, the K value can be different to make the helix higher or lower.
• Mirroring
• Incompatible with Cutter Radius Compensation

Errors

• Commands not allowed:
• G51 P0 - scaling ratio 0
• G51 I5 J5 K0 - scaling ratio 0

Examples

• Scaling at LCS origin:
• G51 P5 - Scales the part x5 times along each axis
• G51 I2 J3 - Scales the part x2 X direction and x3 Y direction
• G51 J-1 - Mirrors the part along Y axis
• G51 P-2 - Mirrors and scales the part x2 (flips the part 180 degrees around the origin point)
• Scaling with the center at some position
• G51 X10 Y10 P5 - Scales the part x5 around (10, 10) position
• G51 X20 Y10 I-1 J2 - Mirrors the part along X axis, scales x2 along Y axis, scale origin at (20, 10) position.