Through screen and Normal to Screen Options

[treddie]

Sorry to rant here, but why is PTC so &*(%#*)(@?~! brain dead when it comes to something as simple and grade school as this:

In the attached image you can see that I have a horizontal datum plane, and I am looking at that datum plane edge on. You can also notice that I was able to put in a datum point that passed through an edge of the part, and through the datum plane. With those, I put in an axis that is normal to the plane and passes through the point.

Now, I know that ProE W4 has the ability to choose "Normal to Screen" as an orientation option, but why they brain fart and don't offer it in this case is beyond me and I'm tearing my hair out. The reason is that I simply want a new datum plane that is normal to the plane I already created (remember, I am seeing it edge on), and that passes through the normal to that plane (the axis I created) AND IS NORMAL TO THE SCREEN! Since ProE "knows" the orientation of the current view, then the viewplane is a momentary datum plane in its own right. Why it won't accept that as a parameter is beyond me.

And why they don't offer its cousin, "Through screen", is just as beyond me. This is simple linear algebra stuff.

What do I do?!

HEEEELLLPPP!

 

[treddie]

After some extra work, I found a somewhat inelegant solution.

Some of my work is based on imported, free-form meshes, so that the position of a given datum plane is open to interpretation. The meshes have to be converted into ACIS .sat, solid files so that ProE can make intersections between planes and solid. Once in ProE, the orientation of many datum planes have to be eye-balled. But this is Ok, since their final placements do not need to be incredibly precise. But that is where the problem was...when I would find a screen view that was "perfect" for the placement of a datum plane, how to tell ProE to create either a vertical or horizontal datum plane, normal to the screen and through a particular point on the model?



The convoluted approach I found was this:
1. Pick the spot on the screen where you want the vertical or horizontal datum plane to pass through. If the spot just happens to have a CSys there, ignore step 2.

2. At the point on the object where you want the plane to pass through, place an arbitrary CSys. IT MUST BE ON A NODE. It does not matter how it is oriented. when the "Coordinate System" dialog pops up, go to the "Orientation" tab, click inside the first, "Use" collector to highlight it and click anywhere on the model (line, node, anything selectable). This will rotate the CSys to a new orientation, and will also automatically highlight the second collector. Click anywhere on the model again, to set up the final orientation of the CSys, and click "OK".

3. Place another Csys on top of the existing one by selecting the old one in the model tree. When the "Coordinate System" dialog pops up, go to the "Orientation" tab. You will notice that its options are different for this 2nd CSys. Click on "Set Z Normal To Screen", and then click "OK".

4. The new CSys will be oriented with its x-axis parallel to the top and bottom of the screen, y-axis parallel to the sides of the screen, and z-axis perpendicular to the screen.

5. From this final CSys, you can build your datum planes.

It is somewhat of an inelegant approach because you have to create the 1st "sloppy" CSys (ProE will not let you create the 2nd CSys in the orientation you want without it being based on a prior CSys!). Unfortunately, you cannot just place an arbitrary CSys on the model somewhere and have this special screen orientation, without the prior CSys (go figure!)...ProE's Coordinate System > Orientation dialog is different for the 1st and 2nd CSys's. So you are stuck with the sloppy CSys as yet another feature cluttering up your model.