Hi all, have a problem coupling 0.25 motor shaft to 3/8 allthread and 1/2 acme leadscrews. 'Real' couplers are too expensive. Bought some cheaper couplers of the fork and rubber spider type in the appropriate sizes but there's runout on the thread section and the shaft moves around. Tried drilling and tapping smaller sizes to larger and still have the problem. Tool or my technique too inaccurate and the part is too soft to use the existing hole as a guide for the larger drill/tool.

Does anyone have any smart coupler methods that I can produce? Tool challenged here, no access to a lathe so its a drill press and table saw only.

thanks