I'm building out an ERCF kit to go with my Trident - it would add a nice utility to the printer, so I want to explore that. I printed the calibration piece and aside from slightly sloppy overhangs on the M5 nut top edges, it all looks good. I tested the 8mm rod's that came with the kit (spot on 8mm diameter when I measured them) but the fit in the calibration piece is almost loose - there's a tiny bit of clearance, it slides in with near 0 resistance and spins easily in the hole. Is that a good fit or should it be tight?