Summary

If the Posted Code or the Program Error Checker displays the error:

The following op has an ambiguous positive side

the selected machining operation cannot determine the correct positive side of the geometry based on the current machine definition.

This error is not caused by the part file itself. It indicates that the Machine Definition Database (MDD) being used requires modification to correctly define or interpret the operation.

Table of Contents

Before You Begin

  • Save your part before making any changes.

  • Identify the machine definition (MDD) currently selected for the part.

  • If you are using a custom machine, verify who supplied the MDD.

Procedure

Step 1 – Verify the Selected Machine

Open the Document Control dialog and verify that the correct machine definition (MDD) is selected for the part.

If an incorrect machine has been selected, choose the appropriate machine and regenerate the posted code.


Step 2 – Verify the MDD

If the correct machine is already selected, the issue is typically within the Machine Definition Database (MDD).

The MDD contains the machine-specific configuration used during toolpath generation and post processing.

This error indicates that the current MDD cannot correctly determine the positive machining side required for the operation.


Step 3 – Contact the MDD Provider

The MDD must be reviewed and modified by the individual or organization that created it.

If the MDD was supplied by CAMCO or your post processor provider, contact them for assistance.

If your company maintains custom machine definitions internally, contact the individual responsible for maintaining the MDD.

Expected Result

After the MDD has been corrected, the operation posts successfully and the "The following op has an ambiguous positive side" error no longer appears.

Additional Information

What Is an MDD?

The Machine Definition Database (MDD) defines the capabilities and behavior of a machine within GibbsCAM. It determines how machining operations are interpreted and processed during posting.

Because this error originates from the machine definition, modifying the part geometry alone will generally not resolve the issue.

Common Causes

This error is commonly caused by:

  • An incomplete or incorrectly configured MDD.

  • Custom machine definitions that require updating.

  • Machine configuration settings that do not correctly define machining orientation.

Best Practices

  • Keep custom MDDs updated with the latest revisions.

  • Test new or modified MDDs before deploying them to production.

  • Maintain version control for custom machine definitions.

  • Contact the MDD developer whenever machine-definition-related posting errors occur.

Troubleshooting

  • Problem: The error appears only when using one machine.

Possible Cause

The MDD for that machine contains an incorrect or incomplete configuration.

Resolution

Have the MDD reviewed and updated by its developer.


  • Problem: The same part posts successfully using a different machine.

Possible Cause

The issue is specific to the original machine's MDD.

Resolution

Compare the machine definitions and update the affected MDD.


  • Problem: Editing the machining operation does not resolve the error.

Possible Cause

The error originates from the machine definition rather than the operation itself.

Resolution

Review and modify the MDD instead of the part file.

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Keywords

Ambiguous Positive Side, The Following Op Has an Ambiguous Positive Side, Program Error Checker, Posted Code, MDD, Machine Definition Database, Posting Error, Machine Definition, Post Processor, Machine Configuration