Do I need a keyway?

[kingcreaky]

In my opinion, id say a grub screw is fine... dimple the shafts and use loctite on the grub screw... perhaps even use two grubscrews (on on either side).

personally, I just use one, with pointed head grub and do it up man-tight.

Matt

[John S]

Never use opposing grub screws, all it does is supply two pivot point for the shaft to rock on.
If you are using two then put them at 90 degrees so the screws force the shaft into a corner