Thanks so much Jordan, however when attempting to open the .ipt, I get the error message “Database schema for file C:\Users**********\Downloads\Aluminum C-Channel 1x3x1x35\Aluminum C-Channel 1x3x1x35.ipt is (20.0 (Build 200096000, 96)), which is newer than this version (19.0 (Build 190159000, 159)) of the software”
Which version of Inventor are you using? Do you know how I could fix this issue? Thanks!
EDIT: Nevermind, I just went ahead and opened the .stp file and it opened correctly. Thanks!
Inventor’s weight calculations for aluminum VEX parts tend to be a bit high. Based on the average density of VEX’s aluminum parts according to the weights VEX has on the aluminum product page and the volumes of those parts, I calculated an estimate of 0.195 lbs for the 1x3x1x35 C-Channel.
Yes, because I just quickly threw this part together at the time, I did not add iMates to it. I am actually considering not using iMates at all in my VEX CAD library for Inventor 2016, but that is another topic.
The diameter does not matter. I usually resize the diameter of all the geometries after adding all the iMates to make them very small (0.001"), but that is just an attempt to keep the iMate glyphs as close to the centers of the holes as possible.
iMates tend to slow down Inventor when all of the glyphs are turned on in a large assembly, and it also makes it very difficult to know which glyphs are for which part. I’ve considered multiple options, such as going back to the circular sketches I used to put on the parts (which can be turned on/off using the F10 key, I believe), or extruding the circles as geometry but not placing iMates on them.
I almost never use iMates. I tend to use a work axis for constraining to the center of the square holes, I’m told by a professional mech engineer this is not such a good way but it works well for me. The only changes I made to the VEX parts after importing them from the STEP files was to assign material, color and (sometimes) weight.
 Double click on the part to edit it
 3D Model->Work Features click on Point and select “Center point of loop of edges” and create points in the center of both (top and bottom) edges of the square hole in the part
 Click on Axis (in Work Features) and select “Through two points” and draw an axis between the two points created in step 
Now you’re setup to align this axis to any cylindrical hole or the center line of a shaft using the “Constrain” options in the Assemble menu.
Is that pretty much how you do it or is there an easier way?
I don’t know if it’s easier but this is what I do.
Create a work axis at the intersection of two planes, select the two adjacent faces inside the square hole. This places the work axis at the corner. Now, edit the two offsets for the work axis, change from 0 to 0.091 (assuming you are working in a standard assembly not a metric one). The holes are 0.182" square so this puts the work axis in the center. I usually create the two or three work axis I need to constrain a part such as a bearing block and then cut and paste the offsets, just takes a few seconds.
Slightly of topic, but help would be appreciated.
I was wondering how to create this corner cut(refer to picture below) in preferably Solidworks, but AutoCAD and Inventor are also fine. [ATTACH]9496[/ATTACH]
On the inventor part of the story:
I think you should create this part in sheet metal, and then go to the flat view, and then sketch on the plane a diamond or some shape, cut and pattern, and then fold again.
I personally went the easy cheating way – a revolve cut… Well, the lazy way…
Working axis? Check.
Easy insert? Check.
Adjustable insert offset? Check.
Look? Well, personally I think it looks better than a few hundred iMate icons crowding my part so that a c channel looks like a piece of fluffy white stuff from far away… lol