drive constraint

[luiww]

I wonder if one can use drive constraint in sketch mode for blocks as I like to visualise how the links move when one dimension changes.

[JDMather]

Yes.

Manage>Make Components  ( I think there is an example in this paper http://home.pct.edu/~jmather/SkillsUSA%20University.pdf )

Post your file here if you can't figure it out.

[luiww]

I tried and not able to grasp the concepts well.  As such, I attached the sketch here.  I like to vary the angle of the link base from 115 deg to 65 deg and see how the link cam varies.

[pcrawley · Accepted solution]

JD's tutorial is awesome.  Here's an alternative that lets you drive sketch constraints without the expense of building an assembly.  I've used it counless times building all sorts of mechanisms that often never get fruther than a concept - hence no assemblies, just sketches.

Try this:

1. Go into parameters and rename your d12 (the 115deg angle) to something useful - like "drive_angle"
2. Go to Manage > iLogic Browser
3. Click the "Forms" tab of the iLogic browser, then a blank area of the tab, right-click "Add Form".
4. You'll see "drive_angle" in the left column.  Drag it under the word "Form 1" on the right.
5. Looking down, you should see some properties of the "drive_angle" parameter.  Find "Behaviour" then find "Edit Control Type" - change this to "Slider"
6. Now you can expand "Slider Properties" and set your limits (115 and 65 degrees, step-size of 1)
7. Press "OK" at the bottom of the "Form Editor" dialogue.
   
   
8. Everything disappears, but you should have a "Form 1" button on the iLogic forms tab.  Press it.
9. Drag the slider and try to stop grinning.

This works really well with sketch blocks too.  If you use skeletal modelling, you'll also appreciate that after using "make components", this iLogic form drives the assembly too.

[luiww]

Excellent instruction and thanks.