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best fasteners for aluminum outside

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  • best fasteners for aluminum outside

    A friend asked me tonite to help build a roof over a scooter for a disabled person. He already had the aluminum tubing bought, so after a couple hours into it I'm at the point where I need to choose from available bolts to assemble the mounting hardware. I can go with common plated steel hardware, or stainless. I suppose I could go with heavy galvanized, but it looks gross. Because this is tubing, I'll be inserting plugs to both cap the visible ends and give resistance to crushing from tightening the bolts. Only question I have is what's the best hardware to use-

    Basically, there will be two pillars holding a more or less flat frame which will have a piece of coroplast attached to it as a roof. The pillars have to attach to painted square steel tubing without having holes made in that. My plan is to pinch the mounting brackets to the tubing using some aluminum angle. That part is worked out, and if need be I can insulate the aluminum from the steel with more paint, or even use a glue of some kind. If the parts are immobile relative to each other, there will be less chance of bare steel becoming available to react with the aluminum brackets.

    So far so good- but I will have to bolt the brackets through the pillars. I would like to use those cap nuts to keep the bolt ends covered so it looks good and eliminates a hazard. Don't want anyone cutting themselves on a sharp thread-

    Anyway, since I live in macrame town, I can get any style of beaded lace or frilly decorative silky fabric I could think of, but I'm a bit limited to the general stock on hand in the various hardware and metal shops. I think I can get nickel plated cap nuts, and I think I can get those as nylocks also. I can get stainless threaded rod and bright plated threaded rod and nut and bolt hardware. A cap nut on either side of the assembly would look nice, but a bolt with a cap nut on the other side would be ok too.

    What would you do?
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  • #2
    I know we all tend to look at stuff via the tools we have, so this may not be a solution for you (and maybe you need this to be such that it can be dis-assembled easily), but had you considered mig welding it? That would be my method of choice without knowing any of the constraints you maybe under, construction wise.


    • #3
      Well, I think if it was me I'd just go with the stainless and be done with it. I made some stainless hinges for an outdoor gate and used stainless lag bolts to secure it to cedar posts, this was about 20 years ago and it looks like it was done yesterday.


      • #4
        I would tend to use stainless fasteners, but you should use something to isolate the stainless fastener from the aluminum tubing to prevent galvanic corrosion. Google a product called "Tef-Gel" to get an idea what I'm talking about. The plated fasteners always seem to get some rust bleeding through eventually, but even if you use the plated you should still protect against galvanic corrosion.



        • #5
          What is the rest of the scooter put together with? SS is expensive, depending on how much hardware you need, and there isn't much need for it to outlast the machine. Most scooters aren't weather rated (though I have no idea of the brand you are working with), and if you are building a "sun" shield, plated would look just as nice as SS.

          Whatever you choose, I would buy nylon locking nuts to match the bolts. Should be a lot of vibration which can loosen hardware pretty quickly. Also don't forget the anti seize if you do use stainless steel.



          • #6
            If tell me what size and how many........I might have something to donate......

            I have a few odds and ends of teflon coated hardware that would offer decent corrosion protection.

            Or if you have time...tell me what need and I could get some done with the next batch.


            • #7
              Thanks for the offer, Cuemaker. I think what I will do is look for stainless cap nuts- failing that I'll use nickle plated.

              One 'trick' I've used in the past is to wax the hardware with carnuba wax before installing it, threads and all. If the hardware rots after a few years, well they can just replace it. The scooter is put together with what looks like bright plated hardware, not stainless. But it's all steel also, so the possible problem with corrosion would be less. In my case, I'm not bolting aluminum to steel, I'm bolting aluminum to aluminum, which is pinching the aluminum bracket to the painted steel. There won't be an actual electrical connection between the two metals. If all I can get are nickle plated cap nuts, I'll just wax it all up and put it together.
              I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-