Do you know that CAM-POST can automatically switch between Polar and Cartesian interpolation to avoid over-travel errors?

Do you know that CAM-POST can automatically switch between Polar and Cartesian interpolation to avoid over-travel errors?

The LIMIT/POLAR command defines conditional Polar interpolation, which enables the post-processor to automatically switch between Polar and Cartesian interpolation as required to avoid over-travel errors. Mill-turn centers often support native polar interpolation. CAM-POST can emulate polar interpolation on a milling machine by rotating the part (with a rotary table) in place of a linear axis.

For example, the machine shown in the image below has only 60mm (2 3/8”) of Y axis travel in the negative direction, but significantly more Y axis travel in the positive direction. This type of machine is an excellent candidate for automatic Polar/Cartesian switching.

Do you know that CAM-POST can automatically switch between Polar and Cartesian interpolation to avoid over-travel errors?

The LIMIT/POLAR command defines conditional Polar interpolation, which enables the post-processor to automatically switch between Polar and Cartesian interpolation as required to avoid over-travel errors. Mill-turn centers often support native polar interpolation. CAM-POST can emulate polar interpolation on a milling machine by rotating the part (with a rotary table) in place of a linear axis.

For example, the machine shown in the image below has only 60mm (2 3/8”) of Y axis travel in the negative direction, but significantly more Y axis travel in the positive direction. This type of machine is an excellent candidate for automatic Polar/Cartesian switching.

The complete LIMIT/POLAR command syntax is shown below.

We can use the following command to tell CAM-POST to use polar interpolation, with any available rotary axis, so as to keep the Y axis output in the range -60:500 mm. The “SCAN,ON” couplet causes CAM-POST to be more proactive in determining when polar interpolation would be beneficial.

LIMIT / POLAR, AXIS,AUTO, YAXIS,-60,500, SCAN,ON

The two videos below show the effect of running the same program with and without automatic Polar/Cartesian switching.

With MODE/POLAR (good output)

Without MODE/POLAR (bad output)

Benefit to User
Over-travel conditions can be avoided by having the post-processor automatically switch between Polar and Cartesian output methods.

For more information or comments, please do not hesitate to contact Phil at TechTipTuesday@icam.com