Parametric Constraint errors

[Anonymous]

I'm having a really difficult time maintaining my parameters when making changes to the part I've made in the attachment.  The control parameters for this part are:

-100 mm distance between 15mm circles

-1 of the 15 mm holes

-30 mm hole

I am new to inventor but I would also like to be able to set up my constraints correctly.  I'm also not sure if my sketches are ideal for this part either.  I usually get an error concerning my fillets from the base to the center support beam when I try to change the 100 to 75.

Any help would be greatly appreciated.

[JDMather]

Sketch1 is unconstrained - start here

http://home.pct.edu/~jmather/SkillsUSA%20University.pdf

and use equal (=) constraints rather than duplicate dimensions.

Sketch2 is unconstrained (and I think it was off-center, but did not double check).

Extra points in Sketch2 on circle.

Sketch3 is unconstrained.

[JDMather]

Top arc and right side (tangent) angled line.

The arc and line overlap each other.

Tip:  When creating a line tangent to an arc click the arc (I would assume at this point still a circle) and hold mouse button down dragging to next arc (Inventor will automatically add Tangent constraint).

Once you get the hang of sketching all of the needed constaints (except =, would be nice if Inventor would do that too) will automatically be added by Inventor - all you need to do is dimension.