Tim Smith

Had a pleasant surprise today - General Profile Tolerance

Discussion created by Tim Smith on Aug 5, 2020
Latest reply on Aug 6, 2020 by Tim Smith

So let me preface this with a couple of items:

  • We have been practicing MBD for about 14 years now. We have done end runs, hacked the system, abused it untill we got models and assemblies looking the way we felt the should visa vie the specs. Over the years this has caused some gripes when it came time to play with the DimXpert module. It's been a long, and at times a rough road.
  •  I do give my VAR and Solidworks grief when something breaks or something new shows up that doesn't work as advertised. See my open letter to Solidworks post Open letter to the solidworks dev team. 

I accidentally discovered the General Profile Tolerance (GPT) tool in the MBD tool set, quite by accident yesterday. For a work flow background, we have tier one vendors that will take a fully MBD solidpart file and run with it. We produce dataset derivatives with tolerances and some overall gross dimensions for regulatory and tier two vendors. We also have a Faro arm with CAD to part inspection capabilities, so we have been doing incoming and in process inspections for about 14 years using this work flow.

When you are using predominantly CNC manufacturing capabilities and doing your QC/QA via CAD to part inspections, you quickly realize that parametric and non parametric product can be full constrained (Toleranced) using a much simpler application of GD&T.

I boils down to datum references and various levels of profiles of surface...….that's it.

Using single or composite profile of surface tolerancing you can control position, and size of pretty much all geometry from a CAD nominal model.

The missing piece of the puzzle was always what to do with all the features and geometry that didn't have anything other than "general" requirements for size and position?

In the past we hacked the system by using the old annotation tool set GD&T callout box. You could get a consolidated frame if you knew what you were doing. (See mbd1.jpg). This served us for almost the entire 14 years we've been doing MBD. Except for the release where they removed the annotation toolset for GD&T and tried to force us to use DimXpert. It didn't go well.

Very recently I've shifted to using collections of surfaces that fall under this "general" tolerance to apply a surface profile to. For simple geometry it isn't too bad to make collections, for anything over 50 surfaces it can be problematic.

So along comes the General Profile Tolerance. Only took 14 years! 

Currently, the way we implement it, it is 99% there. I set up my datums, apply any special profile tolerances, check the Tolerance Status button so make sure any critical geometry is green. Then using the note tool I insert the GPT into model space.

Note: My part and assembly template have a predefined "Global" annotation view.

I ensure this annotation view is active prior to inserting, or if you forget, you can right click and push is there. I just drop it into space, and before doing anything else click in front of the frame and type "ALL SURFACES ARE" hard return the go to the end of the frame, hard return again and type "UNLESS OTHERWISE SPECIFIED". This fulfills the requirements of the ANSI MBD spec. (See mbd2.jpg)

You can see why I am giving it a 1% demerit point as the formatting of the note is a little wonky.

At this point I can insert into the dataset derivative (drawing) the Global annotation view. It looks a little better here but there is still a small kerning issue with spacing. (See mbd3.jpg). 

My last little nitpick with the feature is the fact that in the model space the Show Tolerance Status shows everything green. This indicated that all surface are fully constrained. But in the DimXpert Manager tab the Part1 of the GPT is still blue. In DimXpert parlance, blue entries in this tab indicate a level of constraint, but, not full constraint. I'm off to beat this up a bunch more before I'm fully satisfied. 

Mathew Lorono, well done sir.Matthew Lorono

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