Circle object probe

How do you use carbide motion on a circular object. Not how to cut a circle but how to probe and set in a circle

It doesn’t have a specific facility for this.

Two techniques I’ve used are:

  • use a center finder and mark the center and zero there using a V endmill
  • Cut a pocket the diameter of the circle in a piece of scrap (or the MDF) and place thus
1 Like

I don’t use CM so I cant speak to that, but you can get pretty close by doing the following:

  1. Put in a bit with a sharp point, alternatively use the ground rod supplied from C3D.
  2. Jog the bit to somewhere near the widest point on the left side of the circle and Zero your X-Axis. It doesn’t actually need to be in the center. If you are using a sharp bit put the point on the circle edge. If using a round bit, make the bit tangent with the circle.
  3. Jog only right until you reach the antipodal point. Look at DRO and divide by 2. (I’m not sure if you can enter coordinates in the DRO but if so enter the new number.
  4. Do the same for Y-Axis.
  5. Profit?

When you create the job you do the material set up. In the setup you have an option of the origin as several places and one is the center of the material. So when you add objects to the material everything is relative to the origin you set. If you had a 4" X 4" material and drew a 2" circle and used the origin for X and Y as the center you would simply select the circle and use the alignment tool to place the circle in the center of the material. The alignment tool does not have to have the center as the origin to align things to the center but you must measure your material very carefully or you will be off by a few thousands if your material is not measured perfectly. I use the center a lot and put a piece of painters tape in the center and use a ruler to draw an X from each of the 4 corners. That is the center of the material and when setting up the Shapeoko you use a vee bit to find that spot and set X and Y zero there.