motion manipulation words g32 – thread cutting g15 & g16 – polar coordinates g50 & g51...

Motion Manipulation Words

G32 – Thread cuttingG15 & G16 – Polar coordinates

G50 & G51 – Scaling

G50.1 & G51.1 – Mirror image

G60 – Single direction positioning

G68 & G69 – Coordinate rotation

G68 & G69 – 3 dimensional coordinate conversion

Relates only to turning centers

Commonly taught in basic CNC courses:

G32 – thread cutting (turning centers only)

G32 not commonly mentionedBetter ways available to cut threadsUse G76 to machine threads

N165 G00 X0 Z0.2N170 G32 Z-0.75 F0.0625N175 M04N180 Z0.2

Example: Synchronize feed with speed




Not always taught in basic courses:G32 is similar to G01G32 can be used for tapping





G32 is similar to G01

G32 is like G01 except:1)Feedrate is synchronized with rpm2)Feedrate override switch is disabled3)Successive passes will be in same

tool path





G32 can be used for tapping

Many turning centers don’t have a tapping cycle

Since G32 disables feedrate override…

…use it for tapping on these machines

.

.N150 T0505 N155 G97 S500 M03 N160 G00 X0 Z0.2 N165 G32 Z-0.75 F0.0625 N170 M04 N175 G32 Z0.2N180 G00 X8.0 Z7.0 M03..

Relates only to machining centers

Used to specify positions with polar

G15 instates, G16 cancelsFanuc’s version not very helpful

Center must be program zeroX specifies angle, Y specifies radius

Polar coordinates

Most programmers stick with the rectangular coordinate system

Basic useHow G52 helps

Topics:

Polar coordinates

0

45

+

5.0 diaProgram zero

X45.0 Y2.5X: angleY: radius

Polar coordinates

0

45

+

5.0 diaProgram zero


Polar coordinates

0

45

+

5.0 diaProgram zero

X0 (or X360.0) Y2.5X: angleY: radius

Important limitation!Center of polar system must be program zero

Polar coordinates

Program zero

Polar coordinates can’t be used!




Polar coordinates



Topics:

Polar coordinates

Program zero

If your control has G52 (it’s an option), you can temporarily shift program zero

4.0

1.5

G52 X4.0 Y1.5G15G81 X45.0 Y2.5 R0.1 Z-1.0 F4.0

Since not all controls allow G52…

…many programmers ignore polar coordinates




Polar coordinates



Topics:

Used to change size of programmed path

Can be helpful with 3d workAll coordinates are modified

By scale factor

Scaling

Since CAM systems also allow easy specification of scale factor, this

feature isn’t widely used

Words involvedTopics:

Scaling

Words involved:

G50: CancelG51: Instate scaling modeI: Scale center in XJ: Scale center in YK: Scale center in ZP: Scale factorExample:

G51 X0 Y0 Z0 P0.5½ scale about program zero

Used to change size of programmed path

Can be helpful with 3d workAll coordinates are modified

By scale factor

Scaling

Since CAM systems also allow easy specification of scale factor, this

feature isn’t widely used


Relates mostly to machining centers

Used for right and left hand workpiecesSame program can be usedPolarity of coordinates are reversedGreat for hole machining operations

Milling reverses style (climb vs conventional)

Mirror image

ApplicationWords involvedExample

Topics:On a turning center?

Mirror image

Left hand Right hand

X+ X-

Same program can be used for both!

Mirror image simply reverses the sign for all coordinates in the mirrored axis

Mirror image


It’s not so good for milling operations

Mirror image



Conventional milling

Mirror image



Conventional milling Climb milling

Mirror image



Conventional milling Climb milling

What is conventional milling without mirror image becomes climb milling with!



Mirror image



Mirror image

Words involved:

G50.1: CancelG51.1: InstateX: X origin of mirrorY: Y origin of mirror

Example:

G51.1 X4.0 Turn on X mirror image, center of mirror is 4.0 from program zero



Mirror image





Mirror image


Topics:Full example program is

shown in the lesson text

On a turning center?



Mirror image




Mirror image

X+

X-

Z+

Z-

With most turning centers:

The larger the diameter, the more positive the X value

X4.0

Tool is at 4.0 diameter

With some turning centers,

the X axis is reversed!


Mirror image

X-

X+

Z+

Z-

With these machines

The larger the diameter, the more negative the X value

X-4.0

Tool is at 4.0 diameter

If you have some machines of each

style, it can be very diffic

ult to program

and operate your machines!

(Offsets are reversed too!)

Simply turn on X axis mirror im

age

for the machines you don’t lik

e!


Mirror image

X+

X-

Z+

Z-

Some machines allow tools to cut on either side of

spindle center

Additionally…

Tool requires plus X values

Tool requires minus X values

Some tools will have positive X values

and others have negative X values

Again, programming and

operation are difficult

Now an operator has to know

which tool does the cutting before

they can adjust an offset!

Simply turn on X axis mirror image for all tools that cut on the minus side and

program all tools as X plus!



Mirror image




G60 – single direction positioning

G60 is not often mentionedUse to eliminate backlash from movesCancel with G64 (normal cutting)

.N050 G60 G86 X2.0 Y2.0 R0.1 Z-0.85 F2.0N055 X5.0 Y5.0N060 G64 G80

Example: Single direction positioning

Not always taught in basic courses:

Use for finish boring










G60 ensures that backlash will not affect positioning accuracy

Tool is always approaching from X- Y-







G60 ensures that backlash will not affect positioning accuracy

O0001.N250 T06 M06 N255 G54 G90 S800 M03 T07N260 G60 G00 X2.0 Y2.0N265 G43 H06 Z0.1N270 G86 R0.1 Z-0.75 F2.5N275 X6.0 N280 X4.0 Y4.0N285 X6.0 Y6.0N290 X2.0N295 G80 G64N300 G91 G28 Z0 M19N305 M01.

Invoke

Compatible with canned cycles

G64 (normal cutting) cancels G60

Allows coordinates to be rotatedProgram in the easiest angular positionRotate and repeat

With subprogramming

Coordinate rotation

Words involvedExample

Topics:

Coordinate rotation

Words involved:

G68: InstateG69: CancelX: X center of rotationY: Y center of rotationR: Angle

Example:

G68 X0 Y0 R45.0Rotate all up-coming coordinates by 45

degrees about program zero


With subprogramming

Coordinate rotation


Topics:


With subprogramming

Coordinate rotation


Topics:Full example program is

shown in the lesson text

Allows variable plane selectionG17, G18, & G19 allow plane selection

But planes must be at right anglesAny plane can be defined

Regardless of angleUsed with five axis machining centers

When working on angular surfacesAllows high-level features with plane

Canned cycles, cutter comp, rotation, etc.

Three dimensional coordinate conversion



Words involved:

G68: InstateG69: CancelX, Y, Z: Center of rotationI, J, K: Vectors about X, Y, & ZR: Angle

Example:

G68 X0 Y0 Z0 I1.0 R45Rotate plane 45 degrees about X

Again, once plane is defined,

all features used in the XY,

XZ, or YZ plane can be used

at the custom-defined plane

This makes it possible to

manually program

complicated angular surface

on five axis machining centers

Allows variable plane selectionG17, G18, & G19 allow plane selection

But planes must be at right anglesAny plane can be defined

Regardless of angleUsed with five axis machining centers

When working on angular surfacesAllows high-level features with plane

Canned cycles, cutter comp, rotation, etc.



motion manipulation words g32 – thread cutting g15 & g16 – polar coordinates g50 & g51...

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