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Turbo Talk => Problems => Topic started by: MK1_OZ on July 09, 2019, 05:02:43 AM

Title: Display or Real Error in Alignment
Post by: MK1_OZ on July 09, 2019, 05:02:43 AM
I have created a shape that I need to load into a CFD programme.  Due to CFD issues I have revisited my CAD model and identified a few errors/artifacts to clean up.  In doing so I created the blue shape in the attached file that is to be 3D Added to the grey part in order to form a single Acis solid.

In case it matters this is how I achieved it;
- created a cylinder of the correct diameter (59mm diameter with a centre that aligns with the centre of the round section on the grey object)
- created a temporary copy of the grey object (copy in place)
- quick pulled the flat rectangular face of the temporary grey solid out past the diameter of the cylinder
- 3D Intersect the cylinder and the quicked pulled face to generate the small blue shape

My belief is that the blue shape should therefore be sitting EXACTLY on the flat face of the grey object.

If you look at the attached screen shot, the blue shape is both offset to one side AND not touching the grey shape.  Further, the selection box of the blue shape does not actually align with the blue shape.  It should be noted that the display at that time was zoomed in to the max.  Using the rulers I have determined that the X-error is around 0.000005mm and the Y-error 0.000002mm.  The X-error I could likely live with but the Y-error I cannot as the blue shape must sit on the grey without a gap.

Is this a real error/mis-alignment or is it just due to the extreme zooming I have done?  I have attached the TC file just in case.

TC 2018 Pro Platinum
Title: Re: Display or Real Error in Alignment
Post by: Tim Stewart on July 09, 2019, 08:34:20 AM
Hi MK1_OZ,

    first thing I would recommend, is to increase the precision to 10.
    That gap is not helpful, and, isn't parallel with the grey object.
    Perhaps redraw?

Regards Tim
Title: Re: Display or Real Error in Alignment
Post by: Jeffin90620 on July 10, 2019, 04:15:14 AM
First off, there were no grey objects, so that was confusing.

Instead of a Copy In Place followed by a Quick Pull, I used Extract Entity / Extract face from body (after setting Options / Space / Precision to 10 as suggested by Tim).

The result (on layer New Object) looks like it meets your requirements, but there's a problem.

Your name for this file (Inlet Valve) indicates the Cylinder, Loft and New Object are going to be hollow.  Oddly, New Object cannot be 3D Added to the other pieces.  Trying to Quick Pull the flat surface of New Object requires layer x1 be visible (there's a prior version of the one on New Object there), even though the Quick Pull is being applied to an object on another layer.

Even after making layer x1 visible, Quick Pull fails (probably because of the zero-width sides resulting from the 3D IntersectShell Solid won't work on it (you could draw a Polyline around the edges of New Object's flat surface, then use Offset to the preferred shell thickness and then

I doubt you are going to get what you want from this collection of objects.


Title: Re: Display or Real Error in Alignment
Post by: MK1_OZ on July 10, 2019, 04:30:56 AM
Tim, precision 10 done.  I cannot understand why the parts are not parallel given the method I used to create but will take a look :(

Jeff, lets call it a very dark grey!  Yes the completed physical valve will have a hollow but what I am drawing here is a model of the airflow i.e. the inside hollow part of all these objects are actually solids.  I will play around with what you have discussed and see.

It would appear then that the display issue is actually a real issue and the parts really are not lining up correctly :(:(