For the bushing i used beside the Delrin high quality Steel from1.4548.4 /LN 668. The same I used for the Main Wing Bolts. The tensile strength is 1000Mpa, nicely to work with on the lathe- hard but nice.
Machined it down to approx. 10mm to fit the Delrin Bushing. For the very precise finish I took abrasive paper 240/320 and to polish 700. For the M5 bolt hole I started with 4mm drill, then 4.8mm and finally 4.9mm.
