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G73 / G83 Peck Drilling Reposition Location - Mach4

Symptoms

  • The control does not ascend high enough and bits run into the work piece and break. Or, it ascends too high and the cycle time is unnecessarily long.
  • High-speed peck drilling needs a different retract distance than the system default.

Solution

Mach4 has two machine parameters that affect the reposition behavior with regards to peck drilling.

In versions of Mach 4 older than 4.2.0.3779 (prior to 2018-05-04) these were pound variables.
Mach 4 Machine Parameters were added at that time, moving some system variables and pound variables to the machine parameter space.
Setting a pound variable in G code is done this way: #5114=500

These parameters are available in the MachMotion plugin. Disable the control, then

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SV_HSP_CLEARANCE / #5114

High Speed Peck drilling cycle (G73) rapid retract clearance.
(integer specifying .0001" or .001mm increments, depending on machine units)

This parameter defines how far the tool moves up above the bottom of each peck before rapidly repositioning and then descending for the next peck. If the value is set too small, the tool will hit the work piece and break. If the value is set too large, the cycle times will be too long.

g73-100.png

G code Examples

Machine units are inches
G00 G90 G54 G17 G40 G49 G80					(Safe start line)
G10 L50 N5114 R250 (0.0250")                (Set rapid retract clearance)
G11                                         (Exit parameter setting mode)
M06 T01									(Tool change)
M03 S2500									(Start spindle)
G00 X1.0 Y-1.0								(Rapid to XY position)
G43 H1 Z0.5									(Activate tool offset 1 and move to Z initial point)
G73 G99 X1.0 Y-1.0 Z-1.0 Q0.1 R0.25 F10		(Peck drill cycle start)
X2.0 Y-1.0									(Drill second hole)
X3.0 Y-1.0									(Drill third hole)
G80											(Canned cycle cancel)
G53 G00 Z0									(Return Z to home)
M30											(Program end and rewind)
%
Machine units are millimeters
G00 G90 G54 G17 G40 G49 G80					(Safe start line)
G10 L50 N5114 R600 (0.60mm)                 (Set rapid retract clearance)
G11                                         (Exit parameter setting mode)
M06 T01	    								(Tool change)
M03 S2500									(Start spindle)
G00 X1.0 Y-1.0								(Rapid to XY position)
G43 H1 Z0.5									(Activate tool offset 1 and move to Z initial point)
G73 G99 X1.0 Y-1.0 Z-1.0 Q0.1 R0.25 F10		(Peck drill cycle start)
X2.0 Y-1.0									(Drill second hole)
X3.0 Y-1.0									(Drill third hole)
G80											(Canned cycle cancel)
G53 G00 Z0									(Return Z to home)
M30											(Program end and rewind)
%

SV_FRP_CLEARANCE / #5115

Full Retract Peck drilling cycle (G73, G83) rapid clearance before feed starts.
(integer specifying .0001" or .001mm increments, depending on machine machine units)

This parameter is how far above the bottom of the (previous peck) to command a rapid movement to before starting feed rate moves descending for the next peck.

g73-750.png

For the G83 Full Retract Peck Drilling cycle, the behavior is the same, except every rapid retract goes to the retract plane (R parameter). The HSP parameter does not affect G83 behavior.

g83-peck-drilling.png

G code Examples

Machine units are inches
G10 L50
N5115 R100 (0.01")
G11

G83 X0 Y0 Z-2 R.5 Q.5 F20
G10 L50
N5115 R100 (0.01")
G11

G73 X0 Y0 Z-2 R.5 Q.5 F20
Machine units are millimeters
G10 L50
N5115 R250 (0.25mm)
G11

G83 X0 Y0 Z-50.8 R12.7 Q12.7 F500 
G10 L50
N5115 R100 (0.01")
G11

G73 X0 Y0 Z-50.8 R12.7 Q12.7 F500

Keywords: 14513

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