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Methods to screw aluminum to steel?

dyeager535

dyeager535

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Best practices I suppose.

Purchased aluminum rear interior panels, hopefully before too much time passes I'll get a chance to install them.

Plan to utilize the stock mounting methods (screws into the bedsides plus the stock supports halfway between the floor and bed rails). It's likely going to be exceptionally humid inside the truck for much of the year.

Stainless is a no-no with aluminum as I recall, so probably plated/coated steel screws of some sort? Plastic/nylon spacers to keep aluminum and steel from touching? Or will the paint on the panels and bed mounting points likely provide enough barrier to corrosion?
 
We use regular zinc plated screws with aluminum assembling signs and they don't corrode.

In my experience having both surfaces that are in contact painted keeps them from corrosion.

When we've had engineered assemblies, they usually call out neoprene washers for fasteners thru dissimilar metal panels.
 
Thanks for that info. I'm generally not one for aesthetics, but the panels are already black.

Is there something out there that's already coated/plated that comes black and would likely not corrode that you (or anyone) has dealt with? I know I could paint the screws, but I also know that wouldn't hold up as well as a good coating/plating.

I've had black oxide(?) screws before, but they rusted. I suspect that's just poor quality, but if I could find an alternative that was black and would hold up that wasn't ridiculously pricey, I'd certainly go that route.
 
There is black zinc coating. Example:

Screws, Black Zinc-Plated Steel, Number 10 Size, 3/8" Long

www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
www.mcmaster.com www.mcmaster.com
 
As suggested, use some sort of non-metallic washer on both sides of the aluminum panel to isolate it and prevent electrolysis. Also oversize the hole so the screw doesn’t touch the aluminum.
 
Plastic washers also work well. Fully coated screws is a must. Black oxide rusts no matter what the quality is.
 
Stainless is a no-no with aluminum? There's many bridges in Iowa that are constructed with extruded aluminum guard rails fastened with stainless hardware.
 
Pole barn sheathing screws, they come coated with a conical washer and rubber washer under it.

The aluminum is going to be the piece that gets corroded.
 
JoshHefnerX said:
How about panelbond? Do they need to be removable?
Click to expand...

Will I ever remove them? Probably not. Do I think that I need to make them removable just because? Absolutely. Lol

Actually, based on experience I'll need to be able to get at least the portion around the gas fill off, as that seems to like to rot.

What would actually be pretty handy for this might be something like the plastic rivet-nuts (rivet screw nuts? Lol) that are so prevalent on car undercarriages now. All the ones I've seen are pretty large though, I'd prefer to keep the holes about the same size as factory.
 
Black oxide is just a "pre-rust" coating. Generally useless in anything but a climate controlled building. Even in ideal conditions, it will still rust.

Stainless in direct contact with bare aluminum will result in galvanic corrosion of the aluminum. You need a barrier between the materials. Powdercoat or paint counts as a barrier, but it is subject to wear from vibration in that interface and will still eventually come in contact. Plastic bushings with a washer and bushing down in the screw hole would be ideal. It would prevent wear on the coating and act as an isolator between materials.
 
RaisedK5 said:
I used to use a lot of these in a former life assembling electronic assemblies. View attachment 477401
Click to expand...

With the right diameter, could you just screw directly into those sort of like a drywall anchor? I don't think this will have a lot of load on it, so a small insert like that is doable.

That said, I expect they make pretty small drywall anchors that could be used too??
 
Not so much as an anchor but as a bushing. If you look them up they have some really short ones for thin material. Drill holes in aluminum to the size of the "nipple" sticking out and use a regular sheet metal screw into the stock steel locations. If you're worried about the panel to bracket sandwich something like electrical tape on the back of the panel would "insulate" it from the steel.

Edit to add pic. Im a horrible artist.

1000032078.jpg
 
Your over thinking this.... It's not a jet or nuclear submarine.... They have MilSpec details up the wazoo for dissimilar metals touching.

Plain +;simple, how far do you want to over do it...

Plain steel sheet metal screws

Nylon washer under the screw


A little Teflon type grease on the threads

Back tape the aluminum any place it will contact steel.

You could even fasten with aluminum rivets.

Over the top , blind nuts + fine thread screws
 
I hate to feed the MAW fire, but given the chance to start over, I would love to eliminate sheet metal screws as the panel mounting method - it's too easy to strip out and never seems exactly aligned. You could use riv-nuts or weld regular nuts on the backside. You could also drill all the holes out and use the little spring clip brackets to accept the screws. At least when one of those breaks you can just swap it out. It would also be really cool to make little doors and storage compartments for holding stuff instead of just wasting the space in there, but now we're getting way off-topic.

On a related note, DIY4x powder coats their aluminum dashes and panels (is that what we're talking about here?) and they ship them with stainless hardware (or zinc) and use zinc-coated hinges.
 
Yep, diy4x.

I'm learning a lot about options I wasn't aware of, which is valuable. Kind of the point. If I was set in my ways I'd have no reason to ask.

I'm not there to check the mounting points, but I started thinking a door on the driver's rear would be handy (spare in the way on the other side) I think antifreeze and oil would fit. If the spacing is right for the mount points, I'd imagine cutting the panel vertically where it's still well supported, and using a piano hinge or similar would work decent.

I hate rattles and what not, so I suppose I'd need to just use the stock fastening method and have to undo the screws to get to the gear. But it would be stuff I have zero need to get at for the most part, so it wouldn't be a big deal. Line metal surfaces with high density foam to keep the stuff from rattling around and call it good.

I don't have the capability to weld aluminum, in that regard steel would be a lot easier to make accessible pockets and what not.
 
How? Use ones that are open through both ends and install with the shoulder out?
 
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