Hi Bruce.
There’s a couple of options:
The rough & easy one is to smack the ends of the pipe flat so that instead of being a 2” circle it’s sort of a 3” X 1/2” flattened ovoid. Then it’s easy to weld at a rightangle
The other option is to cut pipe to length - not inside-to-inside but a couple inches longer & then hold a bit of scrap pipe perpendicularly against the edge & just copy thecurve with a marker. Needs a bit of practice & the nicer you get it - the easier the welding
Also, if you can imagine using a, say, 3” holesaw to cut a, say, 2&1/2” pipe in half and if you imagine the curve that would leave? That’s an option that can be very tidy
If you can put yourself in a situation where you cut the horizontals all to identical length & tack them to the legs BEFORE welding the legs to the table -that makes them less length-critical. That’s where it goes wrong - getting the length right
It’s all fun.
Any proper engineer would tell you my table is an abomination probably. But who cares if it works lol