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Help on Simple Parametric part
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June 17, 2010, 09:13:51 AM
I am new to parametric parts.  I just went through the example with the two holes through the plate with rounded corners.  I'm having trouble with what appears to be a very simple upgrade from that example.

I have a rectangular plate with an elongated hole in it.  The hole has arcs on each end.  The trouble seems to be that, once I turn "Add Auto Contraints" on, I cannot dimension the elongated hole in relation to its position on the plate.  The hole is drawn in 2D, then the rectangle and the elongated hole is extruded.  I can move the hole around due to properties in the extrusion, but still can't dimension where the hole is on the plate.

Is this a limitation of v15.2, my computer, or my not knowing how to do this the right way?  Answers appreciated.

UPDATE:  I can get dimensions from the hole vertex to top & bottom edges of the plate, however, with Autocontraints on, they do not show as being Variables.  Then, when using Format / Parametric Part, the hole-locating dimensions do not show up with a Constraint field.
« Last Edit: June 17, 2010, 10:02:15 AM by T. Karlmann »


* June 17, 2010, 09:46:34 PM
I can't open your file because I have an older version.
I recommend doing another sample drawing since it is a simple part and make that one successful, then go back to your original file and try to edit it.
In the new drawing, keep auto-constraints on and draw the profiles ( rectangle and slotted hole). Then dimension the 2d profiles.
I usually add a center mark at center of each radius and make radius concentric to center mark. Then I dimension to center mark and radius moves with it.
The dimensions should show up as variables and you can move the slot relative to outer rectangle. Once it works in 2d profile, you can extrude.



June 17, 2010, 11:17:11 PM
I get  the same results on the retry.  I'm just trying it in 2D only.

I discovered the trim tool does not work when using constraints, and I therefore cannot locate the hole exactly.  I thought of adding a line from the edge of the hole to the part's edge, but there the only command that works is the N-snap, which prioritizes OVER Ortho, so it isn't exact.  If I measure from the arc vertex to the edge, then I don't get a variable -- as before.

It appears that parametric parts are not easy -- once one deviates from F1's example -- so I may have to get along w/o parametric parts for the present.  I'm sure there are secrets and tricks to using constraints, and it appears I'll just have to learn them on my own -- no problem.


* June 17, 2010, 11:47:59 PM
You might try arc vertex to a corner (not edge) of the rectangle.
It sounds like your snaps might be overriding what you want to select.

For distance between two parallel lines, there is a separate distance dimension tool.


June 18, 2010, 01:13:05 PM
I found a workaround to solve the problem I was having.  Thanks for the assist.