Press fit. We did all the math to make sure it won’t slip.
Starting in 2011 or so, we’d ream .001 under and just hoped it would work!
We tested torque required to slip and found it exceeded what we need by a good margin. I mean we used a 3-4 ft lever arm w/ some weights.
Awesome, thanks for the data point! I believe we used a 0.0015 press, which just worked for similar reasons. That was some fun math to do. You can treat the hex like a pressure chamber, and figure out the force required to slip it. I remember calculating that we needed 300 lbs of force to press it on.
This year, we left a step at the end of the bore so we could press it on until it hit the end of the CIM shaft. That worked well. You can see it in the model.
You could also leave a small pilot hole on the end to insert a pin gauge to determine the press depth and to relieve the pressure while pressing on the adapter.