Here’s links to the original temporary build, as well as the heavily modified final build. They’re fairly lengthy, but I hope you enjoy perusing them.
It is a Vevor 0700C (Makita 700 clone)
The nut and 1/4" collet were both supplied with the purchased router, so I’m pretty sure that they aren’t mismatched, or if they are, they came that way from the factory.
Yes, I used the same nut for both the 1/4" (original) and 1/8" (Sienci Labs) collets.
The 1/8" collet has very little runout, even using the original nut that came with the 1/4" collet. The original 1/4" collet has a ton of runout with the original nut. It doesn’t seem to be an issue with incompatible taper or mismatch between the collet and nut, as far as I can tell. I’m thinking that It seems to be a defective 1/4" collet. I’m getting a new collet next week, so I’ll be able to report back then itf it fixes the problem