I've told this story here before, skip if you've heard it!

When I worked elbow-to-elbow with Glenn Erickson at R+E Cycles in the early '80s, we filed all the miters at first. Naturally we got good and fast at it, with two hacksaw cuts to start that got us so close there wasn't much filing to do. We had angle templates precision cut out of fairly stout sheetmetal, at 1 degree increments, in the normal range of bike frame joints so it wasn't too many, and we learned to interpolate the in-between angles reliably to about 2 tenths, plenty good enough for bike frames. Closer tolerances were possible with more time spent, but you have to stop somewhere.

We made a lot of lugless frames too, so this is not just for lugs that would hide poor mitering. We were a bit fanatical about the miters even for lugs, beyond what was strictly necessary. With a little care we could get them "water-tight".

We clamped tube blocks to both ends of a tube before beginning, which ensured the two ends of DTs and TTs were clocked to each other. A trammel to mark out the lengths. We had half-round files in the sizes that cut the correct radius for each joint. Then the miter shape takes care of itself, and you only have to mind the angle and the side-to-side. (I could never understand the need for those templates printed on paper and wrapped around, but maybe those are good for a beginner who doesn't know what a proper miter looks like.)

Then we got a cute little Emco (made in Austria — not Enco) milling machine, and I quickly took to it and started mitering with holesaws, but Glenn preferred to stick with filing, said it was faster. I didn't believe him, so we raced. He won! Only by a little, seconds if I remember right, and my miters were just slightly more perfect, so I like to think of it as a tie. But his miters were beyond "good enough", and he was indeed faster, due to the setup time on the mill. I can't remember if he ever switched over to using the mill, in the remaining few years we worked together before he left R+E to go off on his own. I think not, I think he stuck to his files.

That was for one-off custom frames. The mill would win if you were making batches of production frames, but Glenn never did that.

So my advice for an amateur/hobbyist FB is practice with the hacksaw and files, and avoid buying a big expensive machine to do what you can do with your hands, and just sits there doing nothing most days.

Said the guy who just bought a mill! Eek, what have I done, now I have to get it downstairs and shoe-horn it into my tiny basement shop. It's an Enco (made in Taiwan, couldn't afford an Emco), the dreaded round-column mill-drill, RF-30. But it's heavy and powerful enough to take some biggish cuts in steel once you get it dialled in. It was cheap enough I couldn't resist, and has had almost zero use, it's like a time capsule (OK it's only ~20 years old, hardly an antique.) It came pretty well tooled up too. "Some disassembly required" to get it down the stairs, I am not a heavy equipment rigger. I've instructed Laurie to dial 9-1 and have her finger poised over the next "1" as I winch the heaviest pieces down... I did it with my lathe though, so I'm familiar with the technique.

Why did I get a mill? I dunno, just always wanted one. Hobbyists don't need to justify their hobby to anyone else, IMHO. I ran a Bridgeport at work years ago and a smaller knee-mill for a decade before that, and I've missed having one ever since. But there's just no getting a knee mill down my stairs, nor a place to put one. Tiny house, no garage.

Oh I did consider a Clausing 8530, a knee mill half (or less) the weight of a Bridgeport. But the seller knew how much those are in demand from hobbyists, due to the small size, and was asking about twice what I could afford. That would have been near perfect for me but a little weird, like with morse-taper spindle vs R8 on the Enco (R8 is the Bridgeport size, super common tooling), and the Enco has twice the horsepower. And one third the price. There's a huge community of RF-30 sufferers out there, so plenty of Youtube how-tos, add-ons, fixes for their weaknesses etc.

But I digress! Anyway, do as I say, not as I do.

Mark B