On Mon, 8 Aug 2005, Mr. Plow wrote:
>
> Basically the pipe ends up being brittle, and in a roll-over it will shatter
> rather than bend, so you end up getting no protection, and possibly having
> shards of pipe protruding through different parts of your body. Fun right?
> :)
and that, ladies and gents, is why "pipe is for poop." If you're broke
and need a cage it's probably better than nothing, but it'll only work
once. as a material for a tube frame it wouldn't be up to the task at
all.
>
> The guys that build tube-chassis buggies for rock-crawling tend to use
> 1.5-2" OD tubing with 0.120" wall thickness. Good for strength and weight
> overall. But these buggies also weigh in excess of 2000 pounds, up to even
> 3000 or more.
> So, we all seem to be looking at building a machine that will weigh in
> (including driver) around 1000 pounds right? I'd suggest 1" (or even 1.25")
> tube with a 0.120 wall thickness, and that would definitely be damn strong.
FWIW, just a reminder that the UR machine I brought used 1.25" .035 wall
4130 chome moly tubing. The new rules are giving us a minimum wall
thickness of .065" so mild steel will again rule the day in mini baja (the
only reason for chromo was to maintain strength and get away with a .035
instead of .049 wall). When I get around to building mine I'm probably
going to go very close to baja spec and use 1.25" tube in the .065 to .090
range. There is one huge advantage to the thicker wall (as opposed to the
.035) - it's easy to bend. the paper wall tube just kinks in a bender
unless you find some MAJIK to make it work (like sand-packing the tube or
somethign like that).
>
> When you layout the structure, traingulation is a definite must as well, and
> you can put in little gussets to help in the corners and increase the
> strength of the structure.
gussets of course will up your weight significantly and change stress
vectors a lot (placing stress directly on tube walls in concentrated
spaces...) so I'd say it's better to just make it strong enough in the
actual frame design =)
Of course you could just screw some 2x4s together, or use pvc, fittings
and lots of cement if you want to be really exciting =)
-- MikeM I think I know something. el oh el!
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