Centroid Community CNC Support Forum

Hello.
I'm doing my first experiments with a cnc milling machine.
I have a problem cutting a rectangular frame. I want to cut a square hole. The problem is that the machine does not cut a square but one axis is larger than the other.
I checked the axial movement according to the machine's reading and this part is OK.
Let me give you an example.
The tool is set to a 6 mm diameter cutter.
I programmed a rectangular frame with parameters:
Frame Type: Inside Rectangle
Center X: 0.0000, Y: 0.0000
Lenght X: 314 INC
Width Y: 314 INC
Corner Radius: 5.0000
After that I see that the program shows the value of the X axis as -152,000 and the value of the Y axis as 154,000 mm.
I understand that the program divides 314 mm by two and we get 157 mm and subtract the radius of the tool. Then we get 154mm, and the Y axis has the right value.
Why is the value of the X axis -152 mm, I don't understand? If I remove the value of the corner radius from the program, the values ​​of the X and Y axes in the program are the same. But I can't do that because I need a 5mm corner radius.

Please help solve the problem.

Ilmar

Did you try cutting the part and measuring it?

Did you look at it with F8/Graph, and use the rulers along the left side and bottom of the graph screen to see where your cutter center is?

The reason the ending XY position is different, is because Intercon "ends" a frame cycle at the end of the last corner radius. Since you asked it to cut a 5mm corner radius, using a tool that has a 3mm radius (6mm diameter), the G codes call for a 2mm radius arc at each corner. The last such arc, coming CW around the back left corner, ends at X-152 Y+154.

Thank you cncnw for the answer!
This is a very good explanation for the 2 mm difference in the program.

Now I can be sure that the error is caused by an inaccuracy in my machine, not a program.
I think I need to make a new setting of the motor mm/rev parameters by measuring the longer distance.