Circular Interpolation - Milling a Circle on a Shaft OD.

[TChaseEngineer]

Hello CNCzone,

Machine - Doosan 2600SY
Cam - Edgecam 2017R2

I am having a awful time trying to mill and wrapped circle on the OD of a shaft.

I have been given this example code from doosan. Attached is a picture of the feature and gcode I want to create.

G28U0V0W0
G59G40G98G80
M35
T0303
G97S500M3P12
M90
G28H0
G0C0
G0Z-50
G0X80
G01X65.F300
G18W0H0
G07.1 H50000
G3K-20
G1X80.F1000
G07.1H0
G18U0W0
G0X200
G28U0W0
M5P12

Running this code produces football shapes not circles.
I am a little confused on what the 2 lines between the G07.1 are doing. Anyone have any insight?

I have played with changing the (H50000) and (K-20) and can still only make football shaped no matter what I change them too.

I have created circles by moving the Z and C together in small incremental moves but the circle comes out with a bunch of little flats and not a smooth finish.

I am thinking that this feature can be done with a feeding the Z axis in a straight line while turning the C axis simultaneously.

Has anyone been successful at creating this feature? What does your code look like?

Any help would be greatly appreciated.
Thanks,
Tyler


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[Fletch_CNC]

Running this code produces football shapes not circles.
I am a little confused on what the 2 lines between the G07.1 are doing. Anyone have any insight?

I have played with changing the (H50000) and (K-20) and can still only make football shaped no matter what I change them too.

I'm not 100% familiar with programming with Fanuc, but I'll toss out a couple ideas. First, the lines between the G07.1s define the shape you are wrapping around the shaft (so a G03 fuill circle, and a short G01 line). Second, are you sure you have the right diameter of shaft that you are working with? Also, have you tried changing the H50000 to C50., just to see if that makes any difference?

I don't know if that helps any.

[TChaseEngineer]

Hey,

Thanks for the response.

I tried changing the H50 to C50 and that made the c axis spin about ~30 times.

There is some relationship between H and K between the G07.1 that I don't understand. You would think you could just fudge one of the numbers and bring the football shape into a circle but no. I played with both numbers and it just stretches or squished the football shape. Sometimes it even rotates in 90deg to the z axis.

I tried to hand write this without a G07.1 command and also no luck.

Feeding Z in a straight line while rotating C at a constant feed creates a wrapped diamond shape.

I played around with adding radius moves to try to get a circle,

for example:
2" OD
1/4 EM
1" OD Circle

Z-1.25 C0;
G1 X1.95 F10;
G3 Z-.75 C30 R.375 F20;
Z-.25 C0 R.375;
Z-.75 C-30 R.375;
Z-1.25 C0 R.375;
X3;

This somewhat creates a circle but for some reason the Yaxis wants to move so the EM does not stay on the center line of the stock which makes for an imperfect wrap on the OD.

I am new to live tooling on lathes and would really like to figure this out! Why doesn't the Fanuc example work in my machine!!!

[mcode]

The H value should be X cutting rad. from spindle center (H65. or H65000) assuming your X Radius programming.

[angelw]

Hey,

Thanks for the response.

I tried changing the H50 to C50 and that made the c axis spin about ~30 times.

There is some relationship between H and K between the G07.1 that I don't understand. You would think you could just fudge one of the numbers and bring the football shape into a circle but no. I played with both numbers and it just stretches or squished the football shape. Sometimes it even rotates in 90deg to the z axis.

I tried to hand write this without a G07.1 command and also no luck.

Feeding Z in a straight line while rotating C at a constant feed creates a wrapped diamond shape.

I played around with adding radius moves to try to get a circle,

for example:
2" OD
1/4 EM
1" OD Circle

Z-1.25 C0;
G1 X1.95 F10;
G3 Z-.75 C30 R.375 F20;
Z-.25 C0 R.375;
Z-.75 C-30 R.375;
Z-1.25 C0 R.375;
X3;

This somewhat creates a circle but for some reason the Yaxis wants to move so the EM does not stay on the center line of the stock which makes for an imperfect wrap on the OD.

I am new to live tooling on lathes and would really like to figure this out! Why doesn't the Fanuc example work in my machine!!!

Hello TChaseEngineer,
The "H" value is expressed as the radius of the cylinder being cut irrespective of whether the Lathe is set for X Radius, or Diameter programming. The H address must be specified without a period, that is, in the number of Least Programmable Increments that equals the Radius of the Cylinder.

You must also ensure that the axis that is parallel to the rotating axis is set in parameter 1022. In the case of a lathe with C axis, the parallel axis set in 1022 will be either the X (5) axis, or Y (6) (if the machine has a Y axis). Many make the mistake that Z is the parallel axis, but this is not so. Think of it as the axis parallel to the edge of the unwrapped cylinder (the face of the work-piece). As you will see, the X, and Y axis are parallel to the face of the work-piece, whereas, the Z axis is perpendicular to it. Generally, its most convenient to set this parameter to X (5) and in which case, G18 will be used to set the Circular Interpolation Plane. The syntax for Circular Interpolation will then be:

G02 (G03) Z__C__R__;

Note: I J K Circular Interpolation format can't be used in Cylindrical Interpolation Mode; only R format is allowed.

Regards,

Bill