Help with programming a radius

modelubys said:

Hello, could someone help me with programming this radius using a 2mm radius plate? Here's how I think the program for the clean pass should look:
G0 X111. Z-19.64;
G1 X110. F0.2;
G1 X91.28 Z-29. F0.06;
G2 X83.28 Z-33. R8.;
G2 X91.28 Z-37. R8.;
G1 X110. Z-46.36;

This doesn't produce the correct result, anyone see where I'm mistaken?

Click to expand...

angelw said:

Hello modelubys,

The Start and End points of your radius are wrong. Because you're using "R" Format Circular Interpolation, the control simply calculates a centre point for a Radius based on the Start and End points supplied in your program. Because the instruction is geometrically possible, an incorrect shape (as far as you're concerned) is generated and no alarm is raised. Following is the correct code using I and K Format.

G00 X112.000 Z-15.326
G01 X87.966 Z-27.343
G02 X87.966 Z-38.657 I5.657 K-5.657
G01 X112.000 Z-50.674

and with R Format

G00 X112.000 Z-15.326
G01 X87.966 Z-27.343
G02 X87.966 Z-38.657 R8.0
G01 X112.000 Z-50.674

Regards,

Bill

Click to expand...

modelubys said:

Thanks! How did you calculate this though?

Click to expand...

angelw said:

Hello modelubys,

1.You have to find the I and K values of the Triangle shown in the following picture.
View attachment 212008

2.h (the hypotenuse) will be the Feature Radius minus Tool Nose Radius.
h = 10-2
h = 8

3.because the complementary angles of the triangle are 45deg (the included angle of the lines tangent to the radius is 90), I and K will be the same Absolute value; therefore I and K will be:
I = SQR((h^2)/2)
I = SQR(64/2)
I = 5.657
K = 5.657

4.The centre coordinates of the 10Radius can be obtained from the drawing; X103.28 Z-31.0

5.The centre coordinates of the Tool Nose Rad at the start of the 10rad will be
X = 103.28 – 5.657 x 2
X = 91.966
Z = -31 + 5.657
Z = -25.343

6.The above are the coordinates of the TNR centre; you need the coordinates for how the tool was set. From your original program, it can be seen that the Leading Edge in Z and the point on the insert closest to the machine centre line in X were used (Tool Type 3 setting)

7.To get the X coordinate subtract the TNR x 2 from X91.966
X = 91.966 – 4
X87.966

8.To get the Z coordinate subtract the TNR from Z-25.343
Z = -25.343 – 2
Z-27.343

9.For the tool position at the end of the radius, the X will be the same as at the start of the radius; Z will be the Z centre of the 10radius minus the K value from point 3, minus the TNR
Z = -31- 5.657-2
Z-38.657

When I/K Circular Interpolation Format is used, the I and K values used in the program are distances and direction (+ or -) from the centre of the TNR to the centre of the radius being cut.

Regards,

Bill

Click to expand...