voteshanequinn
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| posted on 23/3/11 at 11:57 AM |
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the best Steel Size
hi everyone.
im building a formula stye car that ive done a rough drawing which ive uploaded. but cant seem to include in a post.
i have just finised gathering some parts and m now moving on to chassis design,
i would very much appreciate if you could let me know the best type (circular or Box Section) of steel & size to use to make a still yet light
chassis frame
Thanks For your help
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daniel mason
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| posted on 23/3/11 at 12:19 PM |
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This thread could get nasty! Or at least the last one like this did. Depends what you mean by best really? A box section is generally easier to
manufacture and to fix to.( bodywork and brackets etc)
take a look at the last thread regarding this, and get your popcorn out.some People on seem more and more interested in arguing with each other at the
moment. Hope you get the info you need and good luck!
[Edited on 23/3/11 by daniel mason]
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deezee
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| posted on 23/3/11 at 01:02 PM |
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If you're starting off, you're going to be better off falling back on what the locosts chassis uses, rather than try an reinvent the
wheel. So 18 gauge, 1" box section. Also may I recommend double checking your post as I had to read it twice to fully understand why
you'd want a "still yet light chassis"?
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40inches
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| posted on 23/3/11 at 01:22 PM |
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Open your image from archive,copy the tag at the bottom and paste into your post.
And allow space for the Locostbuilders "watermark".
 
Description
[Edited on 23-3-11 by 40inches]
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voteshanequinn
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| posted on 23/3/11 at 01:48 PM |
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Thank you; DM, DEEzee & 40" some useful advise
yes i appolagise i ment stiff instead of still (Spelling Grammer is not usualy a Mech Engineers strong point)
I was more intersted in the Dia/size of the steel to uses eg 1 inch Box or 1 inch Pipe. By best i mean i would like to know where the compramise is
between two small ( too weak) & too big (too heavy)
thanks
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deezee
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| posted on 23/3/11 at 02:05 PM |
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quote:
Originally posted by voteshanequinn
I was more intersted in the Dia/size of the steel to uses eg 1 inch Box or 1 inch Pipe. By best i mean i would like to know where the compramise is
between two small ( too weak) & too big (too heavy)
thanks
Like I said, most of the locost space frames are made from 1.6mm thick, 25x25mm box section. I used 2mm thick as it was easier to get hold of and
only adds around 5kg to the chassis weight. Obviously you would now far more than I, being a mechanical engineer, of the strength / torsion benefits,
versus the weight of the box section.
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hughpinder
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| posted on 23/3/11 at 03:25 PM |
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For a 7 style car, 1 inch box 1.5/1.6mm thick is the standard, (with some 20mmbox*1.5). If you use thinner material with a larger box, or higher
tensile material, you start to get into practical problems with welding the thin sections. There are also problems with the higher tensile grades as
HAZ (heat affected zone) aroud the weld may need special treatment to restore the properties of the steel. People tend to use square rather than
round as it is easier to fabricate, even though nomimally heavier for a given tortional strength. If you aer going for an exoskeleton design like the
atom round tube looks better. Thinner material will also be proportionally more quickly weakened by corrosion. There have been some threads where
people have posted the chassis weight. I think on average a 'standard design' with roll bar/back braces and cross brace weighs about 65kg.
If you go for 1.2mm 25*25 and 20*20 box (the next size down) you would save only about 7kg.
Just some things to think about
Regards
Hugh
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designer
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| posted on 23/3/11 at 06:02 PM |
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Stick to the metal from the Locost and you will not go far wrong.
Apparently square is 33% easier to make compared to round.
But, a tube chassis will always look better that a square one.
Is the car for the road?
If so, why bother with the 'bath tap' pedals position, make it a flat floor.
[Edited on 23-3-11 by designer]
[Edited on 23-3-11 by designer]
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Doctor Derek Doctors
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| posted on 23/3/11 at 11:08 PM |
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If you are making and designing from scratch then use 18 Gauge round tube, if you are using th crappy 16 Gauge Box that Locosts use then you might as
well just buy a locost.
Whats the point of designing something properly and then comprimising on the very bae material? Renders your chassis design effort moot.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Peteff
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| posted on 23/3/11 at 11:15 PM |
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quote:
Originally posted by Doctor Derek Doctors
If you are making and designing from scratch then use 18 Gauge round tube, if you are using th crappy 16 Gauge Box that Locosts use then you might as
well just buy a locost.
Whats the point of designing something properly and then comprimising on the very bae material? Renders your chassis design effort moot.
It's probably the same as Westfield and Caterham use as well, it can't be that bad. If you are designing something to be built out of
1" 16g tubing then 1" 16g tubing is the best material to use. If you are designing for round tube then that is the best, a lot of the
stiffness will come from the position and length of the tubes as well as what they are made from. Are you a real doctor?
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Bare
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| posted on 24/3/11 at 02:18 AM |
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Curiously Lotus and Caterham used 18 gauge steel ..Not 16 ga. And Round is considered better all round :-) than square.(which is good in bending,
should the design be so inept as to place the tube in an unfortunate bending condition.
Round though is much harder to join neatly. Also square is easier for pop riveting ali sheet to.
Costin, in his book has a listing of tubes , relative strengths and weights.
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Doctor Derek Doctors
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| posted on 24/3/11 at 02:02 PM |
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quote:
Originally posted by Peteff
quote:
Originally posted by Doctor Derek Doctors
If you are making and designing from scratch then use 18 Gauge round tube, if you are using th crappy 16 Gauge Box that Locosts use then you might as
well just buy a locost.
Whats the point of designing something properly and then comprimising on the very bae material? Renders your chassis design effort moot.
It's probably the same as Westfield and Caterham use as well, it can't be that bad. If you are designing something to be built out of
1" 16g tubing then 1" 16g tubing is the best material to use. If you are designing for round tube then that is the best, a lot of the
stiffness will come from the position and length of the tubes as well as what they are made from. Are you a real doctor?
Not a real Doctor but I am sat designing Parts for F1 cars as I write this. And round is definately a better base material than square if performance
is your goal.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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voteshanequinn
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| posted on 1/4/11 at 12:24 PM |
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the smallest i can find is a 30mm box with a wall of 2mm
or 27mm tube wall = 3mm
has anyone used either of these
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Doctor Derek Doctors
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| posted on 1/4/11 at 12:40 PM |
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quote:
Originally posted by voteshanequinn
the smallest i can find is a 30mm box with a wall of 2mm
or 27mm tube wall = 3mm
has anyone used either of these
Those are both waaaaaaayyyyyy to thick and rather odd sizes.
Can you not just order some CDS 1" 18SWG? Its not that expensive, you can even get it from ebay if you want it quickly.
Or you could even use seamed tube which would be cheaper and strong enough for wahat you are doing.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Ninehigh
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| posted on 5/4/11 at 04:42 AM |
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Now if I remember this right box tubing is easier to weld and generally work with, while the circular tubing is lighter for the strength/stronger for
the weight, but more of a pita to work with as you have to cut fish-mouths (is it?) at each end
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britishtrident
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| posted on 5/4/11 at 06:55 AM |
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Most racers are a mixture ------ square is particulary handy where you have to rivet sheet metal on --- eg the floor.
Your design is going to be a very long wheel base, the structural members that the brunt of compression loads might be best made with 1.6mm
(16swg) to reduce the danger of Euler buckling.
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tug
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| posted on 5/4/11 at 06:24 PM |
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Damn!
I went over board with mine !
Roll over cage is 48.3cm 3.5mm thick, the two main bars are 30x60cm 3mm thick, the rest is 30cm 2mm thick.
pic of chassis in question :
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