Why does everybody weld in plates at the end of the tubes, why not saw it off at the right angle.

a 90 degree becomes 2x45 degrees. It's much easier, nicer, stiffer and faster

something to do with planning i suspect. Had i planed, i would've done all the joins mitred, as it was it was only at the end i realised it was crap.

still, its not too hard to weld squares on.

One of the problems with mitred corners is absolute critical need to be accurate with them, if they are only 1/2 a degree out they wont be square its okay if the inside is slightly undercut but get it over cut and it wont meet, very time consuming also.

Trust me on this one, Im a joiner and often have to cut them in wood, enough said

Craig

well, I am using mitred corners. It look much nicerand is a lot stronger.

thereby I can use the CNC saw, so accuracy wont be a problem

I can't think of that many places on a chassis where you will need to mitre a joint. In fact I can't think of any only the square bit of the base that forms the seating area. You could make that out of one length of steel but it wouldn't achieve that much in terms of adding strength, just complicate it.

yours, Pete.

well, you can use it in any corner. eg 45 degrees becomes two times 67.5 degrees

formula: 90-(corner you need/2)

so 90-(45/2) equals 67.5

Mitres are fine for tree wood, but not for welded joints, they are weaker, have a massive potential for distortion, and start getting a little difficult when you have 3 dimenional joints.

If you want closed ends but dont want to use end plates, use double stepped joints, awkward to make but stronger than straight butts.

Can you explain what a double stepped joint is. I am not english, so i don't get the words.

Thereby I think that mitres are stronger, but I have to do a stress analysis on that. I will show the results

This diagram shows, you increase the welded area and reduce the tendancy to distort
Rescued attachment Not Mitres.GIF

Ok, I get it, can be done at a 90 degree corner. But it would be hard to do so at any other one.

I don't see that it would be that much harder. You just have to make an angled cut through three sides of a tube rather than a perpendicular one. Not significantly harder than the cuts for a mitre, I'd think.

Before you start cutting the tunnel the only tubes that I can see that would benefit from mitres are B1, V and the L assembly, though if you did LC the corners might interfere with the nosecone. Be nice if V were mitred in terms of flat sides to weld the round tube onto and bend the ali round, but I heed Mark's words of wisdom.