Does the box section used for the chassis need to be extruded or can it have a seem running down it, as in the one shown in the attached photo:



Also is there a recermended amount of carbon which the steel should contain, or is bog standard mild steel ok?

Most people use what you have shown - ERW.

I did.

I don't think you can get RHS without the welded join, it would be prohibitively expensive for locost use anyway. Compare the price of ERW and CDS round tube to see what I mean.

Normal ERW is fine as is plain carbon steel.

The only thing carbon content increases is the strength in tension/compression of the tubes, so it is possible to use a thinner wall tube for the same yeild strength. Carbon content does not affect the stiffness (youngs modulus) of the tubes in anyway!

Most race series take account of this by not making exceptions in the rules for thinner wall tubing if something like T45 is used.

David

[Edited on 14/3/06 by flak monkey]

Plain low carbon steel -- that way there is virtually no danger of brittle fracture around the welded areas.

The thickness should be 1.6mm (16swg) or the nearest standard metric size 1.5mm.

Depending on the manufacturer the welded seam on the box section can be in the centre of a face or in the corner -- chassis have been built using both without any problems.

I made my own taking sheet steel and bending round a former then welding. Took a good bit longer but very satisfying
Alex

oh my god - respect !

(but why didn't you just buy it ?)

If you have any doubts about the strength of the weld, just cut off a slice and try beating it to death with a big 'ammer.

It should just flatten out with the weld intact - if the weld breaks then send the whole batch back!

David

I think he was kidding, like he fetched old washing machine sides and beat them round a former, locost style. I friction welded mine by rubbing them together really fast, it's the only way to do it properly

hmmm, was a rough day in the office (well helpdesk )

quote:

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Originally posted by lexi
I made my own taking sheet steel and bending round a former then welding. Took a good bit longer but very satisfying
Alex

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get out of here,

fred would have mined the ore with a steam driven something or other (having first rebuilt the steam engine over 10 years) then made the steel and as an after thought made it into box section whilst explaining in the olden days they'd do it ten times faster and to a much higher standard.

All the while we'd be gawping at the tv thinking we're not worthy. Always said he's the one bloke I never wanted my dad to meet even though they only lived 10 miles apart. Dad would have ended up being his go-fer / best mate / partner in crime.

Well the box section passed the smash it with a hammer test so it looks like I've got a supply of box, just need to make up my mind regarding a chassis design. Note a small lump hammer choosen for testing purposes.

Use a bigger hammer!

Caber