The drop in twist style nuts damage the extrusions as the surface is small and ribbed. The wider ones that can only be inserted from the ends don't fit in regular slots (at least for the 2020 series), they only fit in the beveled openbuilds version to allow a wheel to run in the slot bevels. My favorite by far is the springloaded ball one. They can be inserted directly into the slot (needs some encouragement using a screwdriver sometimes) and stay put, even when you hold the extrusion vertical. This can be essential if you're halfway a build and you can't hold the nut in place due to plates/casing obscuring the slot.
I build my NFAN 3D printer exclusively with the spring loaded nuts and low profile M5 allen key bolts. I'd buy 300 nuts, I bought 200 and quickly ran out of them
You also probably going to need to buy 6, 8, 10, 12, 15, 20, 25, 30mm etc. bolts as well, since the slots are only about 5-7mm deep, the bolts really need to fit well unless you plan to cut them to length yourself. 8, 10,12 and 15mm ran out the quickest, so make sure you buy more of those.
Edited 1 time(s). Last edit at 01/25/2019 10:49AM by imqqmi.
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Kind regards
Imqqmi
NFAN CoreXY printer:
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reprap.org]