topic Re: please stop automatic constraints in Inventor Forum

please stop automatic constraints

Anonymous — Fri, 10 Mar 2017 13:04:19 GMT

Another case of Inventor adding stupid constraints behind your back.

I'm modelling a screwchannel in a profile with enough parameters to have full control and the necessary geometrical coupling to keep my life simple. See what happens. This is a sequence that starts with a shared sketch controlling diameters and position, a single plus a patterned cutout.

Extrude, cut the open end, cut out free space for screwthread, pattern.

After doing this I check the position in the profile and move the channel to the left, to better align with the profile that is using the channel.

This is getting too close to the side but I know I have the ablility to rotate the open end. Let's see if we can use this as a solution.

Oops. "Houston, we have a problem."

What happened ? The sketch had a parallel constraint to keep it in the same angle as the cutout. Inventor added a horizontal constraint when the sketch was dragged in place. This was not in conflict with the original orientation of the channel, but now it is.

Whenever you drag sketch geometry around the automatic constraining kicks in. PLEASE STOP THIS. I'm the designer, I know how it is intended to work !

Alex

This was a failrly easy one to detect and correct. 🙂

Re: please stop automatic constraints

-niels- — Fri, 10 Mar 2017 13:16:59 GMT

I think this has to do with constraint inference, though i've never really played with these settings:

These are all enabled by default, which i guess most users will never change, but when you're doing parametric stuff like you're showing i can imagine it's not desirable behavior.

Hope these settings can help somewhat...

Re: please stop automatic constraints

Anonymous — Fri, 10 Mar 2017 13:27:35 GMT

I have a limited set of constraints being applied. After all you want some things happening when sketching 🙂

Most of my sketching however is done with one finger on "CTRL" which - contrary to the word 'control' - leaves the sketch uncontrolled by constraints. This free sketch is fully controlled by me afterwards. What happens with the sketch above is the result of dragging geometry in place. I didn't want to redo everything from scratch so I copied sketched geometry from one part to the other. Since 'paste' inserts the sketch at absolute coordinates I needed to drag it into (approximate) position. The moment you get your finger off the mouse button after dragging Inventor kicks in with automatic constraining. Silently !!!

Should I drag with my finger on CTRL to keep IV from doing this ?

Re: please stop automatic constraints

PaulMunford — Sat, 11 Mar 2017 11:50:42 GMT

There is an application option to turn constraint inference/persistence preference from horizontal and vertical, to perpendicular and parallel that might help you.

You might also find it helpful to 'Move' your geometry rather than dragging it.

I've no idea whether dragging with your finger on CTRL suspendes persistent constraints - did you try it? What happened?