Countersink Diameter for Flat Head Screws too Small

[Anonymous]

The countersink diameter created for flat head screw clearance holes using the Inventor Hole feature dialog is too small.  This causes the head of the screws to protrude above the surface of the part.  This is a problem.  The countersink diameter should be equal to or slightly larger than the "theoretical sharp" dimension to insure that the surface of the fastener is flush with or below the surface of the part.

[leowarren34]

Pretty much defeats the object of a countersink then...

[mschindler-mum]

Hi @Anonymous,

I can understand you what you mean, but in general you can edit the "Clearance.xls" located with the default installation of Inventor in the following path: C:\Users\Public\Documents\Autodesk\Inventor XXXX\Design Data\XLS\XXX2

Note:

• XXXX = means the version of Inventor, for example 2020
• XXXX2 = means the language pack you installed, (with languagepack) for example en-US, another is for example de-DE for the german localized installation of Inventor

I hope this help you, as Workaround at this time.

Kind regards,

Matthias Schindler
CAD/CAM/PDM technical specialist at

[leowarren34]

Cheers @mschindler-mum, a solution for now that if this picks up can be properly used.

[rhenstenburg]

I have edited Clearance.xls for my company but it seems silly to rely on customers to do this for themselves.  Autodesk should update their tables so the rollouts for each new version are correct.  One and done! 

[jtylerbc]

This can be a bit of a pain.  We don't use countersunk / flat head fasteners a lot, but when we do, we always have to fiddle with the countersink size.  I suspect we often miss it and the shop just makes in work despite what the print says.

Does anyone know where the default Autodesk values actually come from?  Just wondering if the values are something Autodesk came up with, or if there's actually a standard out there somewhere that tells us to make these holes in a way that doesn't make a lot of sense dimensionally.

[rhenstenburg]

I use the values in Machinery's Handbook for "Hex and Spline Socket Flat Countersunk Head Cap Screws" (Table 6 under Cap and Set Screws in my version). Don't use the machine screw values.

[leowarren34]

@jtylerbc Would definitely be interesting to find out where ADSK got their data from...

[corym]

This has been a problem for as long as I can remember - I have always just edited the clearance file. When I started my last job, they had about 30000 drawings using the out of the box Autodesk sizes. The machine shop always just made them to fit, rather than to print.

I would love to know where Adesk got their values...

[rhenstenburg]

My recollection is that the fasteners database was purchased.  So, where did the original company come up with their data (certainly does not match Machinery's Handbook values) and why wasn't the data vetted by Autodesk?

Speaking of vetting ... Beyond the matter of the countersinks being incorrect, have you noticed that there are missing fasteners in many of the series in the CC database.  In addition, there are some that are included in the database that I have never found on the market.  I have copied the fasteners that we use to our own library and I add and delete fasteners as we find the errors (and if I'm told about it).  A slow process.  Would have been nice if these were vetted as well.

[corym]

Agreed - I handle our content the same way here. We do not use the standard libraries for anything - other than a starting point...

[jtylerbc]

@rhenstenburg, regarding the fastener sizes in the table, my understanding is that they are based on sizes listed in the ANSI (or other applicable) standards, rather than the sizes that are commercially available.  So it makes some sense that there would be sizes in CC that are not commonly available in the real world, and that you might find sizes in the real world that aren't specifically detailed in the standards.

Not saying there aren't some cases in CC that are simply mistakes, but the "standards" explanation probably covers a significant portion of them.

[rhenstenburg]

Thanks for your point, @jtylerbc, and I understand the disconnect between published standards and what is commercially available.  Bottom line, copying the CC libraries that are commonly used, as a starting point, and updating as needed is a necessity to free designers from worrying about the trivia of fastener availability when solving the bigger problems. 

For those starting out with Inventor and CC, it would be nice to have a database that is as clean and accurate as possible.  I recall that this fastener database was acquired back in the days of Mechanical Desktop.  How carefully was it reviewed when acquired?  Has it been reviewed since (in the past decade)?  I can't say with absolute certainty but I believe that there are errors.

[jtylerbc]

I have no idea how often anyone reviews the default CC data - probably not often enough.  I was just pointing out that a portion of what appears to be erroneous may just be a case of blindly following the data from the published standards without regard to real-world availability.  I definitely wasn't saying that's the only type of error present. 

I found some myself when I built our custom families.  I don't remember specifics, but there were some problems that may or may not have been fixed in releases since then.  As I recall, most of them were duplicate lines in the table, that had a slight difference in the filename column.  When I changed the table over to my company's desired naming convention, the filenames became duplicates (because I had removed whatever differentiated them before) and I started getting error messages.