I'm not getting the precise angle i need when trying to create 90 degree bends in 2" square tube. I cut the tube at 67 degree cuts (45 + 22.5), flip it, and it comes out at 45 degrees (more or less) when measuring the resultant angle of the 2 pieces together. But when i do it again to make the second bend, the three pieces end up coming out at slightly less than 90 degrees. Is my math completely F'ed or am i just going about it the wrong way??


See picture (http://www.ukjeeper.pwp.blueyonder.co.uk/jeep/angles.JPG) for visual aid. The red line on the wall shows what the parts look like when cut the way i'm doing it (slightly exaggerated for clarity). The arrows show the angles i'm creating to make a 90 degree bend.

Your math is correct. Your cuts are just a little off. You say you make the cut at 67 degrees but it should be 67.5. You are making four cuts and losing 0.5 degree with each cut. That will put you off by 2 degrees. If your cuts are not precise you may be off by another degree or two.
Now when you weld the two pieces together you will tend to pull the inside radius closer due to warpage. These things all add up together and you can easily be off by 4 - 5 degrees without even trying.

Try again but before welding everything up, butt the long ends against a 90 degree corner to see if your cuts line up the way they should. If not, clean them with an angle grinder before tacking them in place.
Go slow, you'll get it.

^absolutely right, next time before you weld put everything together and make sure it looks like you want, if not grab the angle grinder. I'd also put it in a jig or something to hold it while welding....and I'd turn the heat up on that welder if you can.

ukjeep,gaps don't hurt anything,in fact filling gaps with weld metal is stronger than butting them.cut the pieces close enough,clamp to a table the way you want them and weld 'em aint rocket science