I am trying to make a clamp to hold a ball about 3.5" in dia. So I would like to make a bowl shape in a peice of wood for the top and bottom, (a mold). I am having trouble getting started. I am using Mach3, Auto CAD R14, and Corel draw X3. on a vertical mill. Could some one point me in the right direction?

Thanks
cut2spec

Do you want to do it with only the software you have?

If so, here's one way. Draw a profile view of your "bowl". Offset the line to the inside the radius of the tool you'll be using. Draw a line representing the top of the board. Then offset the "top" line down by whatever depth of cut you want, and continue to offset to the bottom. Use the intersection points of the inside bowl offset lines and the depth of cut lines to draw a circles, which will be your tolpaths. Put each depth on it's own layer. Bring this .dxf into Mach3, and assign the proper depth to each layer.

If you don't know what I'm talking about, do a solid model in AutoCAD. Subtract a sphere (your ball) from a box (your board) and export as an .stl. Download the trial version of MeshCAM from www.meshcam.com and create your g-code.

If I have this right you say I should draw a 3D picture of my mold and import it in to Mach 3, set my layers and try to cut it. This is what I thought I should do but I feel this will still be 2 1/2D not 3D. Move to the layer feed down, move to the new layer feed down. How do I get all three axes to move together?

No, it only needs to be 2D. I made it too complicated.

Edit: After I made these pics, I realized that the circles drawn are the center of the ballnose tool, not the tip. You'll need to offset your Z by the tip radius.

Draw you ball with a line through the center. Offset the ball the tool radius, and offset the center line down for each pass you want to make. You'll want more passes at the bottom. Then draw a line from the intersection of the depth lines and offset up to the center. Rotate the drawing 90°. Use the center of the original circle as the center for all the circles you'll now draw. Start with one that intersects the offset circle. Then draw a circle that intersects each vertical line. The depth of this circle is Z= 0 Each circle needs to be on it's own layer, and the depth of cut for each layer is the depth of the vertical line.

You'll want to add additional circles at each depth to remove the stock, and keep them on the correct layer for the depth they need to be. You can toggle the layers on and off to make it easier to see. Hope the pics help.

To program to the tool tip, do what I originally said, and draw circles through the intersection of your depth lines and offset circle. Then draw a line from the bottom quadrant up to the center line to locate the cutting path circle.