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Sunday, March 06, 2016

Showing Trimmed Edges in an Inventor Model

My father had many a humorous saying.  One I remember came from his days as an aircraft mechanic for over 40 years.

"Mark it with a micrometer, mark it with a chalk, cut it with an axe."

It was a humorous reference to the futility we all encounter in our careers, whatever it may be.

I was reminded of this saying when I was reproducing a part that had a note indicating that a piece of standard extrusion was going to be "trimmed to fit.".

Technical translation?  "Here's extra material, so you can make it fit in the field".


An example of "Trim to Fit"

But how do we represent that in the print?

In truth, there are several ways you could accomplish this.  The one I present here, is just one idea.

First, offset a work plane the desired distance from the edge to be trimmed, in this case, I chose the maximum of .093 inches.

The first step is creating the work plane.
After the work plane is created, choose the Split command, and chose the "Split Bodies" option from the dialog box.

Make sure to choose the work plane as your split tool.

Splitting the bracket

Once that is done, create your drawing as you normally would.  But you'll notice there's a bold line where the solid representing your bracket was split.




Now comes the trick!  I'm going to make the lines representing the trimmed section dashed.  This can be done by right clicking on the lines, and choosing "Properties".

Changing the lines from solid, to dashed

Once this is done, the part to be trimmed can be clearly seen!


The indicated lines are dashed! 
There's the trick, but why use it over several other methods, such as creating sketch lines in the model, or drawing or perhaps only splitting a face?

Here are my reasons, I only ask you to consider them.

  1. Splitting the part doesn't create any extra files, this approach keeps everything in the part (*.ipt) file. 
  2. Changing the lines is easy to do, the split creates a "natural break", which prevents having to create any sketch "trickery".
  3. The split can be moved pretty easily, by changing the work plane's offset.  This let's you represent the geometry more accurately if you desire. 


So there are the reason I chose this method.  Feel free to see what you think, and use this tip should you ever need it!



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