Ok, after reading all your advice, and to be honest all of you are really telling me the wright thing to do, its just im kind of in the 'denile' stage of thing(
), i went out to recheck everything, check measurements, angles... Here are my problems(ps having a book to hand may be handy, unless you know the diagrams off by heart). atm, the main thing is that u1, u2 dont fit in properly. I tried to figure out why, starting by measuring all the lengths. The only length that i cut that was out were ff2, and ff3, and the longer part for ff2 and ff3)the 290mm bit is about 292mm, but i think this is because the bend in the tube isnt perfect. Ok well what i said originally about ti being 9mm off if wrong, as i realised when i was measuring it i had taken all the clamps of the board as i needed them to hold tr1 and tr2 in place for welding. The meant that the whole thing has been raised by about 5mm and was supported by friction on the wood blocks that were used as guides along the drawings. This means that the front is actually 359mm not 355mm. the gap between u1 and tr1 is around the 4mm. So im nopt sure as to how to lower the frond without redoing the nose. I could also try cutting the bottom of ff2 and ff3 with a cutting disc and then weld that back to ff1 to fix it.
Also i was saying earlier that fitting tr1 and tr2 was very ight and required force as u3,u6,u7 and u8 may not have been welded completely square to the base. So i had to just bend it abit, but i was aware this would happen while welding, so i had only lightly tack welded u3 and u6-8 to the base.
Also the 3mm tolerance i was talking about only really applied to the diaganal between rectangle br7-10 which was just over 805mm rather than 808mm. Apart from this everything else is perfect