David Jenkins
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 posted on 23/7/02 at 01:01 PM |
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Metal thickness for a petrol tank
Another question! 
I have been offered a quantity of 0.8mm stainless steel, together with access to a BIG metal folder.
What's the general opinion of this thickness for a tank? I've seen the Lolocost tanks and they look just as thick (just as thin?).
Any views?
David
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Alan B
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| posted on 23/7/02 at 01:25 PM |
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David,
It's a bit like the old floor question really.
Sure it's strong enough, no doubt, but stiffness is the issue. You may have to add a few more ribs or baffles, but I'm sure it will be fine.
Are you good stainless welder? or do have access to one? This would be an important question IMO, as that is pretty thin for non-expert welders. TIG
job I'd say for sure.
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David Jenkins
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| posted on 23/7/02 at 02:33 PM |
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Alan,
I have a TIG (scratch start DC) that I have used to weld stainless. I actually found it easier than mild steel, as it forms a nice pool that's easy
to manage (apparently due to its poor heat conductivity).
I have used it weld some shim stock about 10 thou thick - no reason for it - just to see if I could! It was quite easy using the autogenic
technique... fold up the edges by roughly the thickness of the metal, clamp the folds together, then use the folded-up bit as the 'filler rod'.
I'm not bothered about the discoloration caused by the heat, as I intend to paint it anyway.
As I said before, my only concern is the thickness of the material - you're probably right about the ribs, etc. It could be more trouble than it's
worth, and it may be better to pay real money and get some 1.0mm or 1.2mm sheet.
cheers,
David
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Alan B
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| posted on 23/7/02 at 02:55 PM |
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David,
It doesn't sound like the welding should be any problem. You are right about the autogenous welds too, I always try to get a lip designed into parts
when I automate TIG (saves a wire feeder )
Part of what I do is here if you are interested.
http://www.desicodesign.com/Arc-welding.htm
The 5th picture is a stainless TIG application.
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David Jenkins
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| posted on 23/7/02 at 03:08 PM |
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You're right about the wire feed!
As you know, TIG requires the following actions:
1. maintain the arc length
2. work the foot pedal
3. move in the right direction
4. move at the right speed
5. feed the filler wire
My MIG is entirely manual - I can manage 4 out of the 5 quite well, but can't do all 5 together properly! At least autogeneous welds means I
haven't got to worry about the filler wire.
cheers,
David
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Nick Davison
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| posted on 24/7/02 at 08:06 PM |
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Is it possible to weld stainless with mig and stainless wire on a roll?
Nick
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David Jenkins
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| posted on 25/7/02 at 07:42 AM |
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Yes - but I believe it's nowhere as easy as mild steel.
I haven't tried it myself, I hasten to add. Something to do with the way that SS is a poor heat conductor - you get local overheating leading to
holes. I believe that you should use pure argon as well, instead of an argon/co2 mix, but don't quote me on that.
Othe people may have another view! I'm sure it's the way that most professional fabricators weld SS together.
cheers,
David
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Alan B
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| posted on 25/7/02 at 12:38 PM |
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quote:
Othe people may have another view!
Not me, I agree, it's a lot more difficult. One of the big problems is that the wire is very stiff and feeds badly and often you need to use a spool
gun (as you do with ali, but that is very un-stiff).
I'd be interested to hear from someone who does it regularly, as my experience of stainless MIG is limited and dated.
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stephen_gusterson
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| posted on 25/7/02 at 07:58 PM |
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i had my dad get a mate to weld a tank by TIG out of 1mm stainless.
It was 'seam welded' along the extreme edges, that allow effectively a big area of metal for less burn though (so I guess...).
my tank is temp out of the car, so if you want a piccy of how it was done, shout and i will send or put one up.
you MIGHT just be able to see how its done on the pics in my folder in TOL....
atb
steve
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