Parametric trimming/dividing in NX

[Raddy13]

I'm working in NX-7.5 and trying to make a parametric involute gear part; i.e., I want the user to be able to enter the number of teeth, pressure angle, and diametral pitch into the User Expressions and NX will spit out a gear (I know that such parts already exist out there, this is mainly a technical exercise). I've got my involute spline drawn and mirrored, and all the dimensions appear to change correctly as I vary the parameters. The issue now is how do I get NX to recognize where to trim the curves regardless of what variables are input so that the sketch can be extruded and patterned?

I want the tops of the involute curves trimmed by the orange circle, and then the radial lines from the involute curves trimmed by the green circle, and where those lines get trimmed will vary depending the parameters (as will the shape of the splines). Any help is appreciated!

 

[mmauldin]

When you select your curves for the extrusion, use the "Stop at Intersection" option and select the portion of the curve you want to use.

 

[Raddy13]

I tried that, but it didn't work when I changed the parameters. What did end up working was changing the sketch selection filter to "Region Boundary Curves" and it appears to be working correctly. I put two gears into an animation assembly and they meshed (using 3D contact, not the gear joint) without interference, right along the pitch diameter. I attached the file if anyone wants to take a look, it's free to use and feedback is appreciated. Thanks for the help!