Display Pitch Diameter on an External Thread / Custom Thread Designation

[tdswanson]

Hey all:

When we make an external threaded part, like a stud or something, I'd like to save my lathe guys some time looking things up by showing the pitch diameters on the thread callouts.

I've looked through some posts on this and it doesn't seem like there's an easy way to do it in an automated fashion, even though the data is in the Thread.xls file.  I'd really like to not have to look it up to make every print.

First, I thought I'd just use the "Custom Thread Designation" field, but as soon as I changed it in the XLS file, I kept getting alerts in Inventor saying that there was an error in the thread family because the callout applied to multiple fit classes or something like that.  So that didn't work out very well.

So....

1. Is there a way to do this?

2. What is the point of the "custom thread designation" infrastructure?  Am I not using it correctly?

thanks!

[pcrawley]

Stick with your first thought - edit the threads XLS file.

The error you are getting is to do with the thread classes - some threads are listed with multiple class options and probably didn't apply your changes to all the class options.  I haven't explained that very well because I'm not sure how to... Take M10x0.5 - it's listed twice; once for 6g and again for 4g6g.  You probably only made your changes to the 6g entry - you need to do it for both.

To work around it, just backup a copy of the spreadsheet, then delete all the rows you don't need.  (You can always reinstate them from your backup copy if you need to.)  Remember to restart Inventor in order for it to re-read the spreadsheet after making your edits.

[tdswanson]

Well, I tried that, but I'm still not sure what the intent of that field is.  Please see the attached image.

The message seems to indicate that it's a problem that the "thread designation" field (column C) has more than one "Custom thread designation" (column D).  

I don't really understand why they wouldn't have placed the fit class within each field in (column C).  When you thread a part, you have to choose the thread designation and the fit class as two separate fields.  So even if I was to change column C to include the fit class, it would almost seem like a person could choose a descripition from one row and a fit class from another.

This doesn't seem to make a lot of sense to me.  Thoughts?

[tdswanson]

And here's a shot of my XLS file

[pcrawley]

I think the problem is that you've edited column D - "Custom Thread Designation".

Try deleting that, and just putting the extra information you need in column C - "Thread Designation"

[tdswanson]

I wondered about that as well, but won't that affect threaded holes as well?

I'll try that in a bit and experiment a little......

Thanks!

[pcrawley]

Will it affect threaded holes - yes.  

You could always duplicate the entire spreadsheet tab, give it a new name (like "Specials").  The different tabs in the spread sheet represent the different "Thread Type" options you pick when setting the thread specification.  Just use the "Specials" when you want your extra information shown in your drawings.

[tdswanson]

That's a good idea, hadn't thought of that.  Seems like a bit of a chore to go through, though.

Do you know what AutoDesk's intention is with the "Custom Thread Designation" field?  Am I not "customizing" in the manner that they intended?

I guess I'm basically asking, how's it supposed to work?

Thanks again for your help!

[pcrawley · Accepted solution]

Ah - I see where you are going.  The error you are getting in the earlier post is because you have 3 identical designations, but each has a different "Custom designation".  

This does not work:

3/4-10UNC       3/4-10-2A UNC

3/4-10UNC       3/4-10-3A UNC

3/4-10UNC       3/4-10-1A UNC

Because the three "custom designation" values are different.

This does:

3/4-10UNC       3/4-10-2A UNC

3/4-10UNC       3/4-10-2A UNC

3/4-10UNC       3/4-10-2A UNC

But the "custom designations" are not the correct values.

The only way to make it work would be to have three different "designation" values:

3/4-10UNC 2       3/4-10-2A UNC

3/4-10UNC 3       3/4-10-3A UNC

3/4-10UNC 1       3/4-10-1A UNC

Or something like that anyway! 

Custom designatons are typically only retrieved in the drawing using this:

[tdswanson]

Yes I think I see what you mean now.  Here are some random thoughts in my head....

1.  I now see why they can't make a "common" designation that includes the fit class....  Because Internals are 2A and internals are 2B and both internal and external thread pull the same designation from that field.  But I guess it is handy having both the internal and external thread data in the same table.

2.  I also now understand that both fields would likely need to be customized in order to accomplish this task (end goal is to display the pitch diameter on an external thread).  But I hardly see this as a victory since every tapped hole would now have a wacky number or some other distinguishing character behind it.  Since I probably do 25 tapped holes for every turned thread, it's probably not worth the questions I would get.

3.  So I'm considering doing what you suggested before: copying the data for the external thread to a new tab to make a "special" callout that will include the pitch diameter.  I'm reluctant to make something too extreme because all future parts would be dependant on opening this customized thread spreadsheet......  But come to think of it, I've already done that with some other styles of custom threaded holes.  So there are already IPT/IDW files out there that depend on this XLS file for their existence.

I'll do some more experimenting and post some more here with what I've found.  Is it me, or should there be a simpler way to utilize the data that's already in the supplied spreadsheet?

Thanks again!

[tdswanson]

OK, well here's what I did and what I found.....

I copied the ANSI UN sheet to a new sheet.  I renamed the new sheet, cleared all the Internal data, and changed the value in cell A1 to "I X Q" for Inch, External only, and TPI in Column E according to AutoDesk's comments in the cell.

Once I stared experimenting, I found these observations:

* When threading an external stud, going to the "Specification" tab reveals this.  The thread designation actually shows column D (not column C) and the fit class shows column F as expected.

* When making a callout on a drawing for this thread, the leader will display this <Column C> - <Column F> unless you choose "Custom Thread Designation" in which it will display Column D only.

So if I were to want to display the pitch diameter in a callout, I found that I had to choose between:

a) Add the fit class to column C, then put the pitch diameter in that cell, and clear the fit class field.

or 

b) Leave Column C as is, add the fit class and pitch diameter to column D.  For each leader, I'd need to change the leader to "Custom Thread Designation" so it would display column D.

Ultimately, I gave up on this project because every time I add an external thread to a part, I need to remember to change the standard to my custom tab, then I would also need to remember to change the callout to "Custom" per option B above.

I just found that it's a lot of jockeying around to accomplish what seems to be a simple goal.  I just don't see the other draftsman here remembering to do these things and I don't like messing with the guts of the program this much.  

In the end, if I'm going to have to remember to jump through several hoops, it's just as easy to open the spreadsheet and manually paste in the pitch diameter data.

Anyway, thanks for your help.  Hopefully all this rambling will help someone else wanting to do this.