Brandon, since an alignment table is the foundation tool in my shop, I like it to be as flat as possible within reason. In our frame shop in Ukraine we had a table made out of a slab of steel that was also ground in some manner. I’m not sure of that manner. Anyway it is kinda flat but is still out a couple of mms in the areas distant from the post. I’ve learned how to deal with that (our transportation frames aren’t expected to be made to expensive custom frame specs) but I would love to have the accuracy of my States based cast tables over there. To put it another way the alignment table is my primary building tool and I want it to be as accurate as possible and I would be willing to pay extra to make it that way.
It is possible to use a smaller surface plate around 2’ X 3’ if the post is located in the SE corner.My preference is for a larger table so I can also get the rear triangle on the surface at the same time as the front.My cast iron table is 3’ X 4’.However, I had my cast aluminum table from Wolverine Bronze made 32” high since those 4 extra inches aren’t that important (it is 32” X 48”).Keep in mind that the “picture frame” of the fixture I have laser cut and etched in Ukraine is 45” by 27” and it needs to lay on table when I’m using it so of course I’m biased to have a table as least that large.I think the answer to this question depends on several factors including how many frames you make in the future and the money you have in your bank account and how spacious is your shop.What I know is that you will not regret getting a larger table if you have money and space for it but you might be remorseful for getting the smaller one when working on a rear triangle.