Ahh no worries, I should of realised that there was no special tool.....apart from my eyes that is. Cheers guys. Got a gate to build, will post pics when complete
If you had a lot to do you could always do the opposite ends first, spend time to get them right then string across for the others...bit like a brickie does when laying blocks.
FH Brundle do a jig for welding heads to bar then put the bars in and weld to rail , tack and smack and weld and smack again is the best way , you can get the one at either end welded on , then clamp a straight bar between them then place the others on and tack , that works well !
If your working on a good level flat bench then make a small jig to hold at the right height and square to your top bar. Mark out the centres tack each one then stand up and eye them up adjust as necessary with hammer then tack opposite side check again for all looking square and in line if all good weld around.
Practice is the best method as said tack bang tack but yal get straighter with each one as u get used to them there's loads a factors curved or straight top style of gates I find if your matchin into really old houses your better ta not try to hard as little bits off can fit in well