How to attach t8 nut to plunge router & how to test life of router

the brass t8 nut is 10.1mm outer diameter
steel tube part of plunge router is 14.1mm inner diameter. I was thinking of 3d printing a bushing and using an epoxy to hold it in the tube, but worried it will become loose.
Maybe If I take Dremel tool and score the ID and OD so there are physical grooves.

Anyways these 1/4" bit routers seem to be able to be modified like the European Bosch can be with a little bit of hacking. As long as I can get this T8 nut secure in the tube I will be all set.

plan to run at lowest speed of 16000rpm and see how long brushes last
Can get this or the 2.5 hp harbor freight routers for around $45 in bulk. do people think this would be a decent cheaper alternative to the Ridgid R22002 which costs 3x more?

can you make a plate that looks like mickey mouse that would attach to the two screws above the shaft hole in the picture and then screw the lead screw on to that plate? My mouse drawing skills leave a bit to be desired, but you get the idea:

thanks for suggestion, but the tube goes up and down and those threaded holes would move.

brass piece needs to be attached to tube only