Tig welder to purchase.

[Cooper]

When welding 1/2" pieces does the total girth of the part matter? Is it the heat dissipating into bigger parts that the more amps are need for? This is what I don't understand. Say I have a 1/2"-1/2" part vs a 3' long 1/2" part. Is the penetrating just in weld area or is it more for a bigger part takes more heat to matain welding penetration? Reason is most all the stuff I'm thinking of (that size) will be relative small parts but thick. Not fully understanding the mechanics of needed amperages. And just now realizing that the welder is one part and the heads/torches ect are another expense in tig welding. Like Bo said I don't want to find out I should have gotten a little bigger to start with. I did read somewhere the newer inverters are better for small stuff vs the older transformer types. But as with anything with self learning from the internet I'm trying to sort out what is good knowledge and ignorance. I'm on the ignorant side (just not knowing).
Money pit? Yes , need to have, no, right now I've got more money than brains! Lol!! Slowly changing that ratio