Bed levelling during the start of a print is awkward with the original small grey knobs, these new ones make it easy.
These knobs are as large as I could go without fouling the Y axis rails.
Each one takes two M3 nuts (5.5mm across the flats). The thread pitch is 0.5mm and there are 8 spokes on the knob therefore it is easy to adjust the bed by a known distance, 0.0625mm per spoke. I placed two nuts on a bolt and tapped them in to position so I knew they would work when fitted to the printer.
I tried printing them the other way up which reduced time and resulted in a better finish on the visible face but that meant having to clean up the hexagonal hole where the nuts go which was fiddly. EDIT Correction, the stl files default orientation, boss uppermost, gives better finish but needs the hexagonal hole cleaning a bit.
These won't fit on the Copymaster 3D 500 as the levelling knobs are tight to the Y axis rails.
They may fit other printers with an M3 thread. Overall diameter is 62mm, overall height is 11.5mm with the raised boss in the centre measuring 4.5mm.

Copymaster 3D 500

Doesn't Matter

Yes

0.2

20