Autodesk Inventor

[#1]

I use the Key Generator from the Design Accelerator and drag the red arrow to position the key under the gear.
Numbers change, and when i position the key they disappear.
There is no way to input a precise dimension. am i right?

[#2]

The only way I have seen to position it precisly is to dig into the part the Keyway was created in and Explode the Accelerator feature so you can modify the iFeature by itself.  The problem with this is that once you do this the Edit Keyway in the Assembly becomes broken.  Still not a bad way to get the features down to the part tree.

[#3]

Where is the command to explode the Keyway?

I right clicked the Key Connection, didn't find

[#4 · Accepted solution]

Find the key in the model browser, click on its flush constraint, and change its value.  Is that what you're trying to do?

Also, if you're tying to rotate the keyway, you can accomplish this at the part level with the "Move Face" command, set to "Free Move." Then select "Reposition Triad," move it to a point at the center of rotation, and you can rotate the keyway to a precise angle.  This method still allows you to edit the keyway from the design accelerator, too.

[#5]

Silly me, overthinking the obvious on that one.

Yes, just expand the Key Connection in the browser and adjust the constraint values, the iFeatures in the parts will follow suit.