Install a spindle about 4" thick round it up sand it part off about 4" worth or length.
Drill an undersized hole in the end for the rod to tap into.
Then drill a 1" hole through the side for the sliding handle.
you can use a file, but I used a grinder to cut a slight taper on the end of the rod and then made 3 grooves going vertical about 1.5" in.
Now put a nice blob of epoxy in the hole and screw the rod into the handle. let it sit overnight. (note that it is IMPERATIVE that you screw it in straight).