Start with the post log
When posting fails or gives warnings, Fusion writes a log. It names the error and usually the operation being processed. Many errors are deliberate checks written into the post, for example:
if (workOffset > 6) {
error(localize("Work offset out of range."));
return;
}A check like this is not a bug: it stops the post producing code your machine cannot run. The fix may be a CAM change, or a post change if your machine does support the feature.
Common problems at a glance
| Symptom | Likely cause | Typical fix |
|---|---|---|
| Post fails with an error | Safety check or broken post code | Read the log; fix the setup or the post |
| Work offset out of range | Offset number beyond what the post allows | Use a supported offset or enable extended offsets |
| Tool number error | Tool number above the machine's limit | Renumber tools or raise the limit in the post |
| Radius compensation error | Compensation mode the post does not support for that move | Change the compensation type or lead-in, or update the post |
| Arc alarm on the machine | Arc end-point mismatch, plane or format | Adjust tolerance, arc output or plane handling |
| Rotary turns the wrong way | Axis direction in the post or machine definition | Correct the machine configuration |
| Unexpected full rotary turn | Range or preferred solution settings | Set ranges, preference and rewind logic |
| Coolant missing or wrong | Coolant mapping does not match the machine | Map Fusion coolant types to machine codes |
| Rapids output as feed moves, no tool changes | Fusion for personal use limitations | Use a commercial licence for full output |
Post, CAM or machine?
- Post – the same wrong output appears for every part using that feature.
- CAM – only one setup or operation is affected, often due to settings such as work offset, compensation or tool orientation.
- Machine – the code is correct, but machine parameters, options or offsets differ from what the post assumes.
Posting a simple test part that isolates the feature quickly shows which one it is.
Arc problems
Arc alarms usually come from end-point mismatch or plane issues. Controls check that the start and end points are the same distance from the centre, within a tolerance. Small arcs, helical moves in the wrong plane, or R-format arcs near 180 degrees are frequent causes. The post can split arcs, limit them to certain planes, or linearise them. See G2/G3 vs linearised output.
Rotary axis problems
Wrong direction, full turns and limit alarms are almost always configuration issues in the post or machine definition. Check axis direction, range, cyclic settings and preferred solutions, and simulate with a machine model. See rotary axis limits and rewind logic.
After a Fusion update
If a post stops working after an update, compare output from before and after with the same file. Newer library posts can change defaults or property names. Keeping a set of test files and reference programs makes this fast.
Keep reference programs. They turn "it used to work" into a quick diff.
Fusion post support
See Fusion post troubleshooting, debugging and error fixing and testing and validation.