[cncnewbstudent]

Hi guys, I'm new to the forums and G-Code programming. I'm taking a programming class and I still am scratching my head over how to express a radius, with I and K.

I know that, to create an Arc, you need to double the X, and the radius.
If the radius starts inside, you add the value of the radius, to the start diameter (please correct me if I'm wrong on this).

If the radius starts outside, you do subtract the radius from the diameter.

This is my general understanding on how to do an Arc, expressing it in terms of 'R', but I'd like to know the process of doing it for 'I', and 'K'.

I'm really struggling to understand the radius stuff in general.

[Geof]

The I and K values can work two ways:

One is to specify the center of the circle in absolute coordinates.

The other is to give the distance(s) from the location of the tool to the center of the arc or circle.

I think the second one may be more common.

[cncnewbstudent]

How do I go about calculating/programming these (R,I, and K?) could you show me an example? Thanks

[Geof]

I don't have an example for I and K but I have one for I and J on a mill. The idea is the same. See the pictures.

[txcncman]

Hi guys, I'm new to the forums and G-Code programming. I'm taking a programming class and I still am scratching my head over how to express a radius, with I and K.

I know that, to create an Arc, you need to double the X, and the radius.
If the radius starts inside, you add the value of the radius, to the start diameter (please correct me if I'm wrong on this).

If the radius starts outside, you do subtract the radius from the diameter.

This is my general understanding on how to do an Arc, expressing it in terms of 'R', but I'd like to know the process of doing it for 'I', and 'K'.

I'm really struggling to understand the radius stuff in general.

Freshman's Dream Syndrome.

You do not need to double anything. You are stuck thinking that a diameter is 2 times the radius of a circle. You are not necessarily cutting full circles. Especially on a lathe.

Get a piece of graph paper. Draw your part to scale with the radius in question and indicate your tool path. Then calculate the incremental distance on the X plane from the start point of the radius to the center of that same radius, positive (getting larger in X) or negative (getting smaller in X). This will be your I value. Then calculate the incremental distance on the Z plane from the start of the radius, (positive moving to the right in Z) or negative (moving to the left in Z). This will be your K value.

If you draw it out on paper, you will be way ahead in grasping the concept.

[cncnewbstudent]

Thank's for the help much appreciated.