Haas NGC post fails on indexed 4th axis tapping (DWO disabled) — why isn't this supported out of the box?

nate.schnase — Mon, 11 May 2026 21:20:22 GMT

I'm running Fusion 360 CAM on a Haas TM2-P with an HRT 4th axis rotary table. Machine definition is configured correctly. DWO/TCPC is not used — this machine does not support it (common on Haas 3 axis machines with upfit 4th axis). All 4th axis operations are indexed positioning only — the A axis moves to a position, clamps, and sits there while the spindle does the work.

When I post a tapping operation at any indexed rotary position (e.g., A-90 or A180), I get this error:

Error: Canned cycle 'tapping' is expanded, but following
command is not supported by post.
Unsupported speed-feed synchronization activation command.
Error in operation: '10-24 Tap'
Failed while processing onCycle() for record 2021.

After opening a support case (Case #25893545), Autodesk confirmed the root cause: when the post detects that the spindle axis and the forward direction of the section don't match — which happens at any indexed rotary position — it forces the tapping canned cycle to expand instead of outputting a native G84. The expanded cycle then fails because it cannot write the sync command.

What is the current "safe" workaround?

The only reliable workaround short of editing post source code that will then require testing, is:

Create a duplicate setup with no machine definition (3-axis mode)
Post the tapping operations from that setup to get valid G84 output
Hand-edit the resulting NC file to insert the correct A-axis index moves before each set of holes

Let that sink in. The recommended path for a standard shop operation on a standard machine is to hand-edit G-code — bypassing all simulation, verification, and back plot in the process. Any downstream change to feeds, depths, or positions requires repeating the entire manual process. This is not a workflow. This is a liability.

Why is this not fixed in the shipping post?

This is not an exotic configuration:

Haas TM2-P — one of the most common brands in North American job shops
Haas HRT rotary table — standard hardware
Haas NGC post — Autodesk's own actively maintained post for this exact control
Indexed rigid tapping at a rotary position — one of the most routine 4th axis operations in existence

Autodesk support provided a fix: a ~10-line edit to the .cps file that adds a conditional exception allowing tapping canned cycles to pass through when DWO is disabled and the section is not a true multi-axis move. That fix is known, but they won't say it works, and it is not in the shipping post.

The result is that every Fusion 360 user running a standard Haas NGC machine with a rotary and no DWO hits a hard post failure on tapping and is told post customization is outside standard support scope. Most machinists are not developers. The alternative — hand-editing NC files outside of simulation — introduces real risk of crashes, broken tools, and scrapped parts.

I am requesting:

This fix be incorporated into the official Haas NGC post in the Fusion cloud library
This case be escalated as a confirmed software defect, not closed as a support request

Has anyone else hit this? Is there an existing bug report or ideas post I can add my vote to?

Environment: Fusion 360 (latest) · Haas NGC post (latest cloud library) · Haas TM2-P + HRT · DWO: disabled · Indexed rigid tapping · A-90 · A180

Re: Haas NGC post fails on indexed 4th axis tapping (DWO disabled) — why isn't this supported out of the box?

nate.schnase — Tue, 12 May 2026 14:40:29 GMT

✓ Resolved — Root Cause Found

TL;DR FIX: Open your machine configuration → find the TCP setting → disable it. G84 will post correctly immediately. Why: Machine config overrides the post processor selections for TCPC and DWO

The problem was not the post processor itself — it was a TCP (Tool Center Point) flag enabled in the machine configuration inside Fusion. With TCP enabled in the machine config, the post treats every operation as a full simultaneous multi-axis move — including tapping canned cycles — which triggers the cycle expansion and the resulting sync command error.

Critical details: This machine config has worked for this in the past and only after the April update did this become a problem. I had already disabled both DWO and TCP in the post processor properties with no effect. The error persisted until I disabled TCP directly in the machine configuration. (which I didn't turn on or off at any point prior to the issue) The post-level toggles are overridden by the machine config — which is not documented or intuitive. You will not find this fix by adjusting post settings alone.

This configuration had been working fine for previous programs. A recent Fusion update either added the TCP flag to the machine definition and defaulted it on, or began actively honoring a flag that previous post versions ignored. Either way, a working setup broke silently after an update with no warning.

topic Haas NGC post fails on indexed 4th axis tapping (DWO disabled) — why isn't this supported out of the box? in HSM Post Processor Forum

Haas NGC post fails on indexed 4th axis tapping (DWO disabled) — why isn't this supported out of the box?

Re: Haas NGC post fails on indexed 4th axis tapping (DWO disabled) — why isn't this supported out of the box?