[BUG] Thread Feature Exists in Model Tree but Geometry Shows Only Hole – Serious Data Integrity Concern

[office66YRG]

Hi all,

We have discovered what appears to be a serious issue from our company’s perspective, and I would like to understand what might have happened.

We designed a relatively simple part with threaded holes on the sides (M4 threads). As part of our internal process, another engineer always verifies designs based on 3D scans before manufacturing.

During a recent quality check, it was noticed that instead of proper M4 threads (Ø3.3 mm core hole with thread feature), the model geometry showed only a Ø3.0 mm hole. The quality engineer informed the designer and opened the feature to demonstrate the issue.

What was surprising is that in the feature tree, the operation was defined as a thread feature. However, in the actual geometry, it behaved like a simple hole with an incorrect diameter. After editing the feature and clicking OK (without making significant changes), the model updated and displayed correctly with the proper thread.

For this small part, the issue was manageable.

However, our concern is much bigger:

We have thousands of parts in our library. Most of them were verified in the past. If a customer reorders a previously manufactured part, we cannot be fully confident that the model geometry still matches the original approved design.

Rechecking every part before repeat production is not realistic from a business standpoint — it would be a massive waste of time and resources.

Unfortunately, I cannot reproduce the issue reliably. This is one confirmed example. I cannot say whether it was caused by a software update or something else. Everyone have same version of Fusion. 

For a company that designs and manufactures physical products — often heavy and expensive components — this type of silent geometry inconsistency is a serious risk.

Has anyone experienced something similar?
Could this be related to version updates or thread feature regeneration behavior?

Any insights would be highly appreciated.

I attached a small movie created by quality check. 

Thank you, Mat

[johnsonshiue]

Hi! The behavior does look concerning. It seems that the geometry isn't properly updated. Try going to Modify -> Compute All. Does the hole diameter get updated? If yes, it will be a bug. But we need to know how to reproduce it from scratch.

Many thanks!

[office66YRG]

Hi, I tried using the “Compute All” function, but it didn’t work.

Today the issue happened again. My colleague created some drawings with these problems. I opened them on my computer and the same issue occurred, so it doesn’t seem to depend on the computer. It’s probably something in Fusion.

For reference, I’m using a Windows 11 PC with an i9 processor, Nvidia RTX 4000 Ada graphics card, and 64 GB RAM. My colleague has an Intel Core Ultra 9, also with an RTX 4000 Ada card, and 128 GB RAM.

Please take a look at this strange behavior.

[jeff_strater]

please share the model that this is happening in.  It's hard to say what it going on without examining the model.

For the missing thread features, your video did not show whether this was a cosmetic thread or a physical thread.  If it is a cosmetic thread, there could be a graphics driver issue.

[office66YRG]

Send model in attachment. 

I think there is something related to the rectangular pattern of the main features and the additional features on those “patterned” ones.

Please check next movie. Something changes in the model when I move the slider between operations or when I click “compute all” — I even had some weirder behavior before, but I couldn’t record it. This model kind of has a life of its own.

Can you try check is it happening on your computer too ? 

[TheCADWhisperer]

@office66YRG 

Are you familiar with the setting for Modeled Threads?

[TheCADWhisperer]

@office66YRG 

[office66YRG]

Yes it was also my issue I mentioned few weeks ago, and this issue looks simillar. 

[office66YRG]

Yes, but these strange geometries appeared after I resumed the operation to check what was going on. I'm not sure why. I asked my colleague to redraw it to see if the issue still exists in the new project. 

[office66YRG]

This solution is unacceptable in our company. The reason is very simple: downstream users, such as CAM programmers or machine operators, cannot easily click on the correct position of the thread where they need to drill a hole. When threads are modeled this way, it becomes difficult to accurately select the hole position.

[office66YRG · Accepted solution]

Hi all, 

My colleague drew it again with the same features and sequence, and everything works fine. So I think the issue was caused by one of the older versions of Fusion or by changes between versions at the time she drew it.

Thank you for your attention in this topic, we can close it.