I use bushes for my rudders
They have a flange so can not slip up
or down shaft tube.
Have used delrin as the material
They have lasted 10yrs.
No UV so no problems
Suspect this was not the best choice of
Cutlass bearings are about 1/4 or 6mm
For a 1" shaft
My rudder bushes are about 8mm wall.
I intend to replace them with vesconite or
Same for my cutlass bearings, as vesconite
Is more suited for this use (bushes both wet & dry)
Vernier your measurement & have them made.
Talk to a plastics engineering firm for advice on minimum
I personally would not go less than 4mm
If using plastics.
I am not an engineer
so seek advice.
Consider having them made about .1mm
On the large side if you can not fit them
By freezing then take to them with 180-240 grit
Sand paper & keep checking the fit.
They are no good if loose fit.