It's been done before. It'll be done again. If something goes south, you really aren't out much. I don't hear many failure stories....
I do tend to agree that taper pins are quite stout. Depending on what size tooling and "stuff" you have, it's not "necessarily" going to be "that much" better. How hard can you yarn on that knob? That's a good metric. How hard is your power feed going to yarn on that knob? That's real when you're facing off a surface that was a little more irregular than you first guestimated. You figure it out right quick, but the power feed gears know exactly what's happening, instantly....
Personally, I would do a press fit and/or use a chemical retaining compound. 603 comes to mind, and here's why. It's NOT for securing press fits, but I'm gonna recommend it that way. Don't worry about reaming to a fit, instead, bore your pilot hole. There will be tool marks. That's good. Dial those in close, as you don't want "much" interference at that size. (I'm thinking half to 3/4 of a thousandth interference, leaning towards half), it's a small amount, but verify that as I just pulled that out of my I just think I remember that). It won't take a large press to a very good press fit here (although it wont' hurt). Anyhow, the "texture" from less than perfect "regular" pass on the boring (no finish pass) will give you tool marks that will make the press fit still press and take torque, and (in theory) hold the whole thing together as is. Although it is defnitely a compromise over a "perfect" finish on both parts, the "backwoods" way I'm describing still holds "most" of that. And the Loctite... The loctite retainer compound will still have somewhere to sit, so it doesn't get pushed to the bottom of the hole, where it's useless. It will give an excellent bond in this use case. Best of both worlds, and it makes strong joints. Not for NASA stuff of course, but for one off jobs that aren't getting the plans reviewed by a proper engineer... That's what I'd do. How strong? Better than either joint by it's self, but not the "sum" of the two possibilities if they could both be done properly on the same piece (which they can not, they're mutually exclusive if done correctly).
Dimensionally speaking, I'd probably shoot for a 3/32, or 0.100 inch wall thickness on your bore in the 5/8 section. (no those are not "the same", that's the ballpark figure area. There's no blueprints here). The larger diameter of the "outside part will have a much easier life than the "geometrically challenged" pin on the other part will. Save as much of the "pin" as you can without making the bored wall "too" thin.
Maybe one of your reamers comes out close to that? I'm not doing the math.... But like I say, if you can get a "OK toolmarked finish surface finish inside the bore though, overly pointy tool, or overly aggressive feed to "thread" it a little... Press plus a retainer compound that actually stays... There's some engineers screaming and hollering right now, but it's an option. Unquantifiable, but tested, stout, and functional.
FWIW. That's my thoughts on a subject with as many workable solutions as their people on the internet posting solutions....
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