[DonRotolo]

Madison, the two issues are both related to the threads:

1. The effect of the threads as stress concentrators on the rod. However, if the rod it thick enough, that is, not near it's strength limits, there isn't much to worry about..

2. The effect of the relatively small contact area between the rod and the bearing ID - that is, will the threads mush down from the force? You need to know the force (in PSI) on the thread tips from the bearing, and run that against the yield strength of the thread material (steel?) and if they're on the same order of magnitude, it's a problem. But, consider a 120 lb robot, maybe 10G force, and 0.2 SqIn of contact area (=6000 PSI) at 40,000 kPSI Yield, you're safe. (The contact area is very conservative here - it is likely more, and thus even better). I also ignored that there are two bearings, each taking about half the load, etc.

(There is another effect, the threads and their reaction to torque, but the effect is small compared to the capacity of the rod, and so can be ignored)

So, back of the napkin, seems OK.

Don