What I speak of a generally called a frame fixture or jig. An apparatus that holds all the frame tubes in the right proximity to one another to allow one to weld/braze a bicycle frame. Believe it or not a most excellent job can be done without one or with minimal fixturing.
Yes, I have one. Actually I have three. What does it do for the professional? It makes us much faster while still being accurate. Time is money and in addition to that I am fully capable of screwing up at a moments notice. I have literally looked at a number and convinced myself it says something else so fixtures remove the possibility of making gross errors. It is much easier to look at the seat angle of my Anvil fixture and when the hash mark lines up with 73 degrees, its 73 degrees. Yes it’s a beautiful thing and I highly recommend the fixturing from any of the great suppliers.
I want to say this. If a fixture is not easily set up and accurate when set up I rather not even have it. Yes, I would rather build with a simple surface plate than have a fixture with a headache of a setup, is slow to setup and only opens me up to mistakes. So it’s either a well made fixture, professional solution or table.
Most students have the fixture/jig and numero uno priority when they get home. I press very hard that so much comes before this. Of course the basic hand tools, work bench, vise, torches but the next thing on my list is a flat surface of some sort. You cannot (yes I said it) you cannot do good accurate work with only a frame jig. You must have some way of confirming your work and therefore the surface plate is central to the whole process. Does it have to be a big heavy thing? not one bit. We are not looking for aerospace tolerances here. Many solutions will do.
Wait, there is more! Do you know you can use your table as a fixturing device as well. With some very simple hardware, much of it bought from tooling suppliers for very little money you can build accurately and quickly. One of my former students just did such a thing and I am very proud of what he has done. Pictures to follow. The concept is simple. It was relatively inexpensive and allows for great variations in design. Also it allows for the requisite checks necessary to ensure a well aligned bicycle frame.