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Help, please, understanding some constraints in a sample file.


HCb

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Hello, all. I'm still working on learning Inventor and I'm working through the book Mastering Inventor 2012. I'm often rebuilding from scratch the sample files provided with the book to try to learn the program and modeling better.

 

 

I'm attaching a file from the book examples which I'm trying to reproduce and I've found something I cannot duplicate or understand.

 

 

I started out by making the first sketch named Sketch1 which is the basis for Extrusion1. When I started trying to recreate Sketch2, the basis for Extrusion2, I find that the major rectangle there has only one distance constraint, the 40mm short side of the rectangle. I see no length for the X axis of the rectangle. I see nothing else which dimensions the rest of the rectangle by distance/measurement. I see no construction line across the rectangle which could be pinned to the Origin. I did the Show All Constraints. I see numerous Equal constraints and this has me baffled. When I hover the mouse over the Equal constraint at the right end of the smaller rectangle (for example) the program highlights the Equal constraints for both the horizontal (X axis) lower lines of the projected larger rectangle and the inner smaller rectangle, as well as the right vertical (Y axis) of the large and small rectangles, plus Equal constraints on all four sections.

 

 

How was this done? I cannot find any way to use the Equal constraint to constrain geometry to a ratio between two different lines which is what would appear to be happening here.

 

 

Thank you for your time.

 

 

--HC

mi_4a_018.ipt

Edited by HCb
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Nice.

 

 

Nevermind.

 

 

I kept at this and, true to form, only figured it out after I sent up a flare.

 

 

Easy enough to do, I see now.

 

 

Project geometry from the first Extrusion, the whole face to get a rectangle. Use the Offset and choose that projected geometry. Drag it inside and let it go. Apply a dimension constraint on one of the sides, in this case the leftmost short (vertical) leg was chosen and set it to 40mm. Boom, Fully Constrained inner rectangle with only one linear dimension applied.

 

 

8-/

 

 

--HC

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