Custom thread with Whitworth form BUG.

[HughesTooling]

Seems like custom thread files with a Whitworth form, modelled threads no longer work. There's an example file in this old post that shows it working. If you try now you just get a trapezoidal thread, the default if you don't specify the form. The form is specified in the XML file as type 7, Whitworth form.

This is what I get now. I've tried a couple of old XML custom files that worked in the past but they all fail now.

Just as a test to make sure there are no errors I copied the built in BSP thread XML file, added the thread form as 7 and this also fails. Not sure why the built in BSP XML doesn't have the thread form type set, seems like something that's hard coded into Fusion.

Here you can see the correct form using the built in BSP thread on the right.

Mark

[andypugh]

This does seem odd. 
This page specifies a ThreadForm tag:

https://knowledge.autodesk.com/support/fusion-360/learn-explore/caas/sfdcarticles/sfdcarticles/Custo...

But this is not used in (for example) the ISO Pipe Thread XML. However the thread is modelled correctly. 

I have created my own Whitworth thread XML using a spreadsheet tool that I have developed for the purpose:

https://github.com/andypugh/FusionThreads

And that _does_ include the Threadfrom tag, but to no effect. 

[MKadaner]

I tried all <ThreadForm> tag values from 0 to 10. You know what? Number 8 gives Whitworth form:

<ThreadForm>8</ThreadForm>

If somebody from Autodesk support reads this, please, please update the relevant KB article "Creating custom threads and thread standards in Fusion 360 (autodesk.com)" with this information.

Better yet please fix the hardcoded magic surrounding thread definitions.

For the reference, I attached a working file which produces Whitworth thread for me.

[MKadaner]

Another issue in this area. Even though I can create modelled Whitworth thread, Fusion "forgets" to apply roundings every time I change something in the design. If I edit the thread feature, just open and press OK without any changes, it "remembers" to model the thread properly. And it is NOT a rendering issue. If I export STL when the thread looks trapezoidal, the thread in the STL is also trapezoidal. If I "remind" Fusion the proper thread form, and immediately export again, the STL looks right!

[HughesTooling]

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@MKadaner wrote:

I tried all <ThreadForm> tag values from 0 to 10. You know what? Number 8 gives Whitworth form:

<ThreadForm>8</ThreadForm>

If somebody from Autodesk support reads this, please, please update the relevant KB article "Creating custom threads and thread standards in Fusion 360 (autodesk.com)" with this information.

Better yet please fix the hardcoded magic surrounding thread definitions.

For the reference, I attached a working file which produces Whitworth thread for me.

---

@Phil.E  Can you take a look at this?

Thanks Mark

[Phil.E]

The article references a 3rd party add-in. I can't decipher what is needed here by inference. Please be specific.

[HughesTooling]

@Phil.E I think this page used to have a list of settings for the type of thread. I've looked at a few posts referencing this page for the <ThreadForm> info but it looks like the page has been edited and dumbed down and no longer has the list of thread types! So I guess the question now is could the list be added back?

Looking at some XML files I have.

Sharp   1

Square 5

Whitworth   7 But now seems to be 8

Thanks Mark

[HughesTooling]

Found this copy\paste from the page before it wa dumbed down.

1. go to thread data folder--> [Fusion install path]\Fusion\Server\Fusion\Configuration\ThreadData

2. make a copy of the thread family that you want to customize, for instance: "ACMEScrewThreads.xml" copy to "MyThread.xml"

3. open the "MyThread.xml", change the "<Name>ACME Screw Threads</Name>" to "<Name>My Customize Threads</Name>"(any name is ok, just make sure it is unique)

4. define thread shape for your customize thread: add "<ThreadForm>0</ThreadForm>" under the <ThreadType>, 

        0----trapezoid; 1----sharp; 5----square; 7-----withworth

     if you don't add this, default shape is trapezoid

5. now you can customize anything, including the pitch/diameters...

[MKadaner]

@Phil.E could you also look at this issue please?

> Another issue in this area. Even though I can create modelled Whitworth thread, Fusion "forgets" to apply roundings every time I change something in the design. If I edit the thread feature, just open and press OK without any changes, it "remembers" to model the thread properly. And it is NOT a rendering issue. If I export STL when the thread looks trapezoidal, the thread in the STL is also trapezoidal. If I "remind" Fusion the proper thread form, and immediately export again, the STL looks right!

Let me know if you need more specific steps to reproduce this issue.

[andypugh]

Note that the Whitworth form isn't only relevant to an obsolete British standard, it is also the thread-form of ISO pipe threads, used everywhere except the USA (which uses NPT) 

[Phil.E]

@MKadaner 

@HughesTooling 

I'm asking the team responsible for thread modeling to take a look at these issues.  Thanks for compiling them here.