Copymaster 3D 500 bed levelling knobs

thingiverse

Bed levelling during the start of a print is very awkward with the original small grey knobs, these new ones make it easy. The heated bed cable needs re-routing under the Y azis instead of over otherwise it fouls these larger knobs, this involves unplugging the cable from the mainboard. This is relatively simple but involves removing a cover that exposes mains electricity so unplug the printer from the mains electricity. Also be wary of voiding any warranty. If you aren't happy about doing this you could just replace 3 knobs. These knobs are skinny (3.4mm) otherwise they foul the Y axis rails, the centre boss that contains the nuts protudes a further 3mm. The diameter is 112mm which is as large as I could go without fouling the Y axis limit switch. They need to be spaced off the bed frame with a thin steel washer, <1mm. I have included a printable washer. It is 18mm diameter with a 4mm hole and is 0.8mm thick, scale it in slicer for different thicknesses. I ended up making washers out of clear molded plastic packaging, the sort that may contain a torch or scissors and is virtually impossible to get in to without damaging yourself! I originally printed one with a built in spacer but that means printing with supports resulting in a poor quality rough surface. Each one takes two M3 nuts (5.5mm across the flats). The thread pitch is 0.5mm and there are 15 outer spokes on the knob therefore it is easy to adjust the bed by a known distance, 3 spokes = 0.1mm. I placed two nuts on a bolt and tapped them in to position so I knew they would work when fitted to the printer. Print with the boss uppermost and no support is necessary. I have printed in PLA as that is all I can use but I think a higher temperature filament would probably be better given the proximity to the heated bed and how skinny they are!