When I built a mini-bike frame for my brother, oh about a hundred years ago in high school, It was done without the benefit of a frame table. We did have a prototype frame in the shop to refer to. We also had plenty of clamps and scraps of steel to improvise appropriate temporary holding fixtures. A lot of 'eye-ball' engineering involved, and plenty of opinions from the classroom peanut gallery as well.
Things weren't much different when I worked in a shop in the 70's. We did quite a bit of frame repair in those days. It usually involved referring to similar frames in the shop for checking measurements. Lots of made on the spot 'jigs' and holding fixtures. A large floor mounted vice, A couple of 'rose-bud torches', a lot of 'eye-ball' engineering, and plenty of advice and opinions from the shop peanut gallery...
Lately I've been checking out stuff on the web at various sites, looking at as many frame tables and jigs as I can find. Also going to dig out a bunch of old mags and see what I can find. The main reason for wanting a proper frame table is for the repairs I'm going to have to accomplish on the 1957 Triumph restoration. That pic of the rusty frame parts to the right there will hopefully resemble a straight motorcycle frame. For years I've toyed with the idea of doing some complete frames from scratch. The last frame repair I did was to one of my Honda SL-350's after I was hit by a three/quarter ton van. A large pole-mounted vice, a rosebud torch, large piece of pipe through the neck, and plenty of eye-ball. Managed to get it straightened out, but swore I was going to build a table someday. The last scratch-built frame I did is one for a yet unfinished recumbent three wheel bicycle.
The main criteria will be to have an adjustable neck holding fixture, jigs for positioning frame tubes, and jigs and fixtures for holding axle and swing arm pivot points in true alignment. It has to be highly adjustable and rigid at the same time. If you see any interesting frame table designs out there, let me know. The other thing is not to get too carried away with cost and details. I have found a few designs that are pretty basic, and some that are pretty exotic and involved, as they are designed with mass production in mind.
Someday, I might get ambitious and build my 'dream Triton'. A friend of mine has a featherbed frame I can use as reference. His was modified to hold a Vincent motor, that was returned to a Vincent frame. Another frame I'd like to do is a purpose built flat track frame for a Triumph motor. But for now I'll be happy to get my 57 Triumph frame back in shape.