Just prior to Xmas I converted my manual Sieg SX3 to CNC using A promica kit (3 x Nema 23 270oz steppers, 3x double nut rolled ballscrews, 4th axis kit for a rotary table and intelligent controller ) all powered by MACH3  . I'm completely new to cnc so it's been a steep leaning curve just setting up the machine I use autocad inventor as part of work and have found Cambam very good for making tool paths and G- code from DXFs at a very reasonable price 

I tried to Edit but couldn't   The  rotary filler starwheel (photo above) is 300mm  Dia  acetal (Delrin) . Cut using a single profile and indexing 60deg, using a 4axis rotary table in the C axis position as it was to big to cut as a single profile  . I would like to be able to cut this using C rotation and X movements. rather than the XY movements and a C index. any Hints welcome  

Hello ninoz:
As I understand the problem, you would like to have the rotary table flat, with the machine Z axis perpinducular to the rotary table face. One way to generate a program to use only the X axis, and the rotary axis would be as follows.

Put a dowel pin, same size as the cutter you will use in the spindle collet.
Clamp the machined star wheel in the rotary table, and set the X0.00 on the rotary table center.

Start the measurement at the center of the shape. You only have to digitize one half of the shape cut-out.
Jog the X axis until it just touches the wheel cut-out at center. The rotary table is 0.00, and the X is some positive value.
Write down this X,A dimension. The A dim at center will be 0.00
Jog the X slightly + away from the star wheel.
Advance the rotary table 1 degree. Be sure the wheel does not touch the pin before the rotary table gets to the next degree position.
Jog the X axis in the minus direction again, until it just touches the wheel again.
Write down this X,A dim

Repeat this process until you reach the outer corner.
By the looks from the picture, one half of the wheel cut-out is about 20 degrees.
As the dowel pin get near the end of the pocket, the X will be rising faster, so you might want to make the A advance 1/2 degree per step.
Now you can copy the data points in reverse order, and join the two columns.
You should have a list of  X*.***,A*.*** coordinates that would drive the machine to cut one Star-wheel pocket.
You can increment the A dimension with G91 by 60 degrees, and repeat all the way around.

Have fun.

Hi mrprecise44, Thanks for your reply, I understand your process unfortunately I start with only a drawing of what is required  not an original part, as these are what is known as change parts to suit different bottle shapes.
I will look at the drawing and see if I could produce X,A coordinates for a toolpath  I would really like to use the drawing (DXF) to create an X,A toolpath not an X,Y Path  any tips welcome

ninoz:

Another possibility would to do the same thing in CAD. If you can enlarge the drawing section of one half of the star-wheel cutout (the vertical section of the drawing, and the center of rotation at the left side, you could produce an offset line in cad, which would describe the path of the cutter center.
Generate an angular line from the star-wheel center, that intersects the offset cutter/path line. The CAD program should give you the X axis coordinate, and you already know the line angle, which is the rotary axis degree. A series of points will be the tool path you need.

Another method would be to generate the star-wheel cutout shape, and do an offset line as above. Now, instead of drawing a line from the wheel center, just put in a series of points, and save the X,Y coordinate to Excel. You can now write a formula in Excel to give you two columns of numbers. The first column is the X axis coordinate, and the second column is the Rotary angle, which is from the drawing origin to the point. You can add columns for the symbol X, A adjacent to the numbers, and save an output to a text file, which will be the true cutter machining path.

Also, now that the data points are in Excel, you can add or subract a constant in the Rotary degree column, and make the beginning of the cutting path at 0.00 rotation degrees, making the program a little easier visually, with no plus or minus rotary angles.

Excel is a marvelous program, and I did this once to produce a ellipse tool path, wrapped around the outside of a cylinder for about 40 degrees of cylinder rotation, which included a Y axis offset for cutter comp, so this 2D problem is a walk in the park.

ninoz:

If you do not have a CAD program to play with, may I suggest the program, DraftSight. It is a free 2D CAD program, made by Dassault Systemes of France. They are the parent company of SolidWorks. Do not be put off because it is free. It is one powerful program! The free offer is so more people become introduced to CAD, and hopefully end up buying SolidWorks. You have to register your name etc., but they send regular email notices about amazing    things people have done with SolidWorks.

In addition, they have a huge number of videos for DraftSight (over 40) on Youtube.