Ooper Custom Drum Pedals

G82

Introduction to G82

When making a part it is crucial to remove all excess material from the raw material so that there is only a little bit of extra material to remove for the finel contour on the part. The G82 cycle is used in Okuma to remove external material on the front of the part while machining radially.

G82 for rough facing

Removing excess material

In my experience the most common application of the G82 cycle is to remove external excess material on the face of the part. It can also be used to remove internal material but I will focus on the external and then move over to internal.

Here is coding example of a rough facing on a part with diameter 40 in an Okuma lathe.

G97 S1500 M03 G95 M08
G0 X45 Z3 T040404 ( WNMG 0.8 )
G96 S180
G85 NPLA D1.5 U0.3 W0.08 F0.3
NPLA G82
G0 Z0
G1 X42 G41
G1 X-1
G40
G80
G0 X120 Z12 M9

This is similar to using the G81 but when using G81 you machine axially instead of radially.

Explanation

setting up and G85

- First with G97 we set the spindle speed and on the same line I start the spindle and the coolant.

G97 S1500 M03 G95 M08

- Then I select the tool and approach the part, in this case the tool has position 04 in the turret. On the line after I use G96 to set the cutting speed to 150mm/min.

G0 X45 Z3 T040404 ( WNMG 0.8 )
G96 S180

- On the third line I use the G85 cycle were I define the parameters of the roughing such as depth of cut, feed and material to leave.

G85 NPLA D1.5 U0.3 W0.08 F0.3

Note the it is important to use the right X-values for positioning the tool before the G85 cycle. The X-value mentioned before compared to the final X-value in the G82 cycle has an impact on how the tool approaches and exits the part while it is running the cycle.

The contour with G82

- Now I have defined the parameters of the facing and set the feeds and speeds, all that is left for the facing is the contour, which I define with G82. It is possible to define the contour before G85, but I like to do it this way.

Before I write G82 I write NPLA on the same line, N is the letter denominating the line and has to be followed by either letters or numbers. In this case I call it NPLA from N-PLAne.

NPLA G82
G0 Z0

- After writing NPLA G82 to start the contour I go to the end Z-coordinate of the facing which is Z0, note that I have written W0.08 before which let me leave 0.08mm of material.

G1 X42 G41

G1 X-1
G40

Then I write the simple contour which is just two X-values. The first is slightly larger than the diameter, X42 compared to diameter 40, and on the same line I initiate radial compensation left. The second X-value is X-1 to make sure that the tool passes the middle of the part. I end the contour by writing G40.

G80
G0 X120 Z12 M9

Finally I write G80 to end the cycle and after that us a G0 to retract from the part. In the example above I turn of the coolant but not the spindle. I assume in the example that I will use a roughing cycle with the same tool right after the facing.

Back To G-codes

G81 roughing

G82 for contour roughing

Radial removal of excess material

The other way of using G82 is for roughing, both external and internal. In the coding example below there is a basic external rougning of a contour when it is wiser to use G82 than G81.

G97 S250 M08 M03
G00 X105 Z2 T040404(WNMG 0.8)
G96 S150
G85 NEXT D2 F0.25 U0.3 W0.08
NEXT G82

G0 X103

G0 Z-24

G1 X98 G41

G75 Z-10 L0.5

G1 X25

G75 Z0 L1

G1 X-1

G0 Z2

G40

G80
M05 M09
G00 X999 Z999

G75 - Chamfers

Code breakdown

First I start the spindle and load the tool now placed on position 4 and approach the part.

G97 S250 M08 M03
G00 X105 Z2 T040404(WNMG 0.8)
G96 S150

Then I set the G85 cycle just like I would for the same contour with G81. THe name of the line is set to NEXT as in N-EXTernal, it is very important that it does not have the same name as any other line in the programme.

G85 NEXT D2 F0.25 U0.3 W0.08

Then I name the line where the contour is starting and write the contour. Note that the contour uses left compensation whereas an external contour with G81 would use right compensation. More on this on the page on radial conpensation(G40, G41, G42) and the page on G81.

NEXT G82