Fountain pens. Anyone familiar with the Jinhoa 100 thread size?

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I've been looking at getting some cheap nibs, but I was hoping someone knows what threads they have before I order them. I can't seem to find that info. This way, I can practice with cheap parts.

I find a lot of specs about it taking 2.5 turns to uncap and stuff like that, but no spec on the threads that hold the nib into the pen body.

I was hoping to find that info before I order a set of them so that I can also order the right tap to go into my chuck and thread these so that I can make my own body for the pen.

Just a crazy idea I have been considering. I have always enjoyed a fountain pen for writing things of importance, and seeing as I have some contract negotiations coming up this coming year, I'd like to make some custom pens just for this. Especially given the person I'm negotiating with, I know they will be enamored with such a level of care in the process.