Chassis fabrication

What am I doing wrong here and what can I do to fix it my nodes lineup but the tubes aren't in a perfectly straight line. The fit up on everything is good. Is this something that I need to be concerned about or am I good to weld it out and not worry about it

Are there more tubes that will complete an "X"? If so, I wouldn't worry about it, if the lengths are different between the three cross member bars they won't cross perfectly through the center of the middle tube.

If no other tubes, that would make me lose sleep...

The near bar is too short and the far bar is too long. Not by much though. When I built my chassis I tended to cut everything a bit long, then hand fit it by carefully grinding material away with a flap disc. It's time consuming and dirty. Also, did you mark the center point of the cross bar and measure to that point? As for it being slightly off of straight, it wouldn't bother me, aside from the aesthetics. What's the chassis going to be used for?

Looks like one of the tubes is too long or short. You need to check your angles to find out which. To fix it, you would have to recut the tube. 

Personally, I'd fix it. 

Also, when building something like that, I tack everything. Check, fit, square, straight, everything. Then weld joints one at a time and check everything between joints. Welding will make steel move a lot. 

Structurally it's fine.  You have two little triangles that meet triangulating the big rectangle.   That "kink" is something you are creating in your mind force won't care.  It will go down one hypotenuse, find that cross bar which will resist it moving and then go down the other hypotenuse.   

Generally you want a straight line because a bend increases the likelihood of buckling.  be cause that cross beam exists any buckling concerns are now down to just the length of the two shorter diagonals.  

I would be unlikely to redo it because big round tube is expensive.   Unless it's hugely visible and people are going to mention it all the time I wouldn't worry.  

In reply to jgrewe : no those will be the only tubes in that area 

It's hard to tell from the photo... are you trying to hit the center line of that crossbar? If so, I don't think the long straight diagonal want's to cross the bar at that point.

In reply to nocones :

Thank you for the information this will be my first tube chassis so all the info helps

In reply to DeadSkunk (Warren) :

Road racing

I'm sure someone here could run this through some finite element analysis software and show you how much strength you'll lose with the center lines not matching.  I played with FEA designing chassis' about 25 years ago and can tell you you will get more strength with a well designed tunnel and cowl than something like this in the floor.

If it was me, and I had enough tubing, I would cut it out and try again. Use those pieces for something shorter somewhere else. My trick for an X is to use mason's twine and run it the whole length. Don't go with the center line, place it where you want the edge of the tubing to be. That way you can get a fairly accurate dimension to cut your fish mouths to. I go with the long side because of the way the tubing is held in my notcher.

I have spent over an hour getting one X to the point I liked it.