Nitrogeno25
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 posted on 27/7/05 at 02:04 PM |
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Riveted stainless steel floor
Hi I'm thinking of riveting a stainless steel floor in my chassis (about 1mm). I'm trying to stay away from corrosion and I can get the
stainless sheets pretty cheap (way cheaper than aluminium)
I saw Westfield rivet the floor so I think this shouldn't be an issue.
Any opinion would be appreciated.
Thanks a lot.
Gonzalo
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NS Dev
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| posted on 27/7/05 at 02:28 PM |
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I wouldn't see a problem with that, my floor is rivetted ally (1.2mm) but rivetted stainless would be fine.
I would have a think about what rivets to use, might be a good idea to use stainless rivets as well, don't know what sort of corrosion might set
in on alloy rivets used though stainless into mild steel!
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kb58
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| posted on 27/7/05 at 07:31 PM |
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That's what I did on my Mini, using Monel rivets because that's all I could find. Stainless sheet was used to avoid corrosion from stone
impacts, or worse, running over something that could potentially come through the floor.
However, doing it over... I'm not so sure I'd use it again. Stainless is nasty stuff to work with and it's heavy. Here in Southern
California I could have gotten away with aluminum. Oh well, next time.
Oh, and a buddy somehow got ahold of a sheet of titanium for his car project... bastard. Don't know how hard that stuff is to cut and drill
though.
[Edited on 7/27/05 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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The Shootist
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| posted on 27/7/05 at 08:54 PM |
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Why not weld it....
I think you can weld stainless to steel, at least for low stress apps.
[Edited on 7/27/05 by The Shootist]
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pbura
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| posted on 27/7/05 at 09:07 PM |
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Stainless is even farther away from steel in the galvanic series than aluminum, so potential for corrosion is higher. Good article here:
http://www.ocean.udel.edu/seagrant/publications/corrosion.html
Suggestion: Fasten the floor with 3M VHB tape, using stainless rivets at the beginning and end of each run. My reasoning is that a very few rivets
will not cause much corrosion of the larger steel parts they're attached to.
Pete
Pete
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MikeP
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| posted on 27/7/05 at 09:17 PM |
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I never really got this (my floor is welded). Why use rivets to attach the floor, since they're not any good in tension?
Are your floor panels generally bent around and attached with rivets at the sides? Or are you counting on the glue for tension, and the rivets for
countering any chassis flex?
If didn't weld it, I'd be pretty tempted to use self tapping screws + glue to attach the floor panel to the chassis. Are self tappers are
a bad idea?
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nanosleep
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| posted on 27/7/05 at 10:37 PM |
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You might use the same trick they use on boats. Electrically attach a small piece of zinc to the chassis. The more active metal will be the one to
corrode. This sacrificial piece of zinc will have to be replaced at some point. zinc->steel->stainless, this is the order of decay. So when
your zinc piece is gone the steel starts corroding. I'm not sure how well this will work on a car which isn't sitting in salt water. I
assume the absence of salt water can only be a good thing.
Galvanized steel is zinc (and other stuff) plated.
-Andy
2000 Mustang GT
2003 Mustang Cobra 450RWHP/450RWTQ
2004 ZX-10R
In progress: 67 Mustang with 520ci(8.6L) V8, 600HP estimated
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pbura
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| posted on 27/7/05 at 11:41 PM |
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quote:
Originally posted by MikeP
If didn't weld it, I'd be pretty tempted to use self tapping screws + glue to attach the floor panel to the chassis. Are self tappers are
a bad idea?
Whether using glue or the tape I mentioned earlier, the main objective is to prevent corner peel, so you don't need a lot of fasteners.
I'd lean towards rivets rather than self-tappers, because pull-out strength will be limited for the screws due to the thinness of the material
being screwed into. Probably only a thread or so will be engaged. It wouldn't be hard to do a simple test before committing one way or the
other.
A welded floor's got to be the best for torsional rigidity. I wouldn't worry about a bonded floor falling off, but it won't be as
rigid as bonded AND fully riveted (belt and suspenders). Mixing stainless and mild steel is a special case because of potential for corrosion, so if
it were my choice I'd use just a few rivets to hold the corners.
Pete
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MikeP
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| posted on 28/7/05 at 12:14 AM |
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Got it, the tape/glue is holding the floor pretty much on it's own.
You're quite right about the tape Pete, you don't want the panel to start peeling - I found it doesn't take much force to get the
parts to come apart if it's applied steadily at an angle rather than straight on. The tape bond seems to shear like a crack might propagate.
No idea whether the glue is the same.
It occurred to me that most of you can't get the screws we can in Canada. I use 1/2" #8 Robertson button head screws. The threads are
very deep, and maybe 1/16" apart. They hold really well in tension and I've never seen one show a tendency to back out. Way better in
tension than rivets plus they can pull parts together. Their one flaw is the head will shear off - the robertson head makes it easy over tighten
them, and they weaken if used a couple of times to hold parts for welding...
I think they'd be great for holding a floor in place and for preventing corner shear - easy and cheap as rivets. Unfortunately the robertson
head isn't very pretty, so I use phillips or allen head screws on anything that can be seen and rivets for anything in pure shear visible or
not.
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suparuss
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| posted on 28/7/05 at 05:24 AM |
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i was gonna use what may be similar to what you are describing there. they are jack point pan heads which self drill (bit like tech screws) and are
philips head. i sometimes use em in my job for fixing metal stud work in shop and office fit outs and they grab really well even in the thin tin
studding as well fixing the tin stud to steel roffing trusses etc which are about 4mm thick.
russ.
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MikeP
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| posted on 28/7/05 at 01:16 PM |
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I haven't tried the self drilling ones for anything like this, but I imagine they should work well. The self tapping ones I would use do need a
pre-drilled hole.
I don't really like phillips heads - they're designed to cam out when the torque gets high - fine on assembly but sucks on disassembly.
Robertson and Phillips got into a market battle, Phillips won in the US while Robertson won in Canada so they're very popular here. If
you've never seen them, a Robertson head has a square indentation that fits the driver very tightly. It stays put and you can apply a lot of
torque.
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pbura
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| posted on 28/7/05 at 02:42 PM |
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I've seen the Robertson heads before, but didn't know what they were. Very good design compared to the Phillips, I think.
Torx heads are great but woe if you don't have the exact screwdriver handy!
Pete
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suparuss
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| posted on 28/7/05 at 05:09 PM |
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ahh yes, ive used them for fixing down plywood flooring to steel beams, didnt know what they were called though. ive even got a selection of square
driver bits that i never use!
russ.
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madman280
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| posted on 29/7/05 at 01:09 AM |
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Metal buildings and some semi truck trailers here in North America have sheet metal panels held on with self tapping screws. They generally have a
hex head and a rubber or plastic washer. They can be driven in with a 6 point socket very tight into almost anything. I believe I noticed Deman
Motorsports is using them to hold floors in along with with adhesive.
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