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EWNichol
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Aluminum Backplate Questions

Tue Jan 28, 2020 9:30 pm

I am in the process of making an aluminum backplate. The way I see it I have three options for finishing: anodizing, clear coating/painting, or nothing. At the moment I am leaning towards leaving the plate uncoated mostly because it is a lot easier. I could anodize it, but it would be a pain and cost more than the plate. I have read a few posts on ScubaBoard about galvanic corrosion on aluminum plates. I doubt it is as significant as some make it sound, but I would like to hear what you all have seen.

Questions:
- How have your aluminum plates held up?
- For those with uncoated plates have you noticed any corrosion?
- Is isolating Steel-Aluminum contact with a rubber washer worthwhile?

Thanks!

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Chris
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Re: Aluminum Backplate Questions

Tue Jan 28, 2020 9:41 pm

Nothing looks worse than a flaking coating. I go un finnished, but I also get my aluminum from a boat builder, there are different qualities of aluminum. I've been using mine for a few years now with no corrosion. Course, I rince my gear too.

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Chris
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Re: Aluminum Backplate Questions

Tue Jan 28, 2020 9:43 pm

I have not noticed any problems where my stainless bolts go through the plate. Although I do use a little bit of silicone grease on the threads.

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Formerly tripplec. Decided to use my real name since you guys aren't a bunch of flaky internet trolls.

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Bryan
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Re: Aluminum Backplate Questions

Tue Jan 28, 2020 10:00 pm

Being the Hillbilly I am, my 1st VDH aluminum plate was left to it's own devices from day one and I could care less how it appears then or now.
Good electrostatic plating holds up great.....poorly done it gets water underneath it and bubbles up quickly. Anodizing looks amazing but seems to scratch off easily. Cerakoting wears like iron till you get a good gouge in it but even then it can be touched up.
When I make them again I will do black electrostatic painting by the vendor that did them last because they have held up well and I liked the results.
I will admit that I'm not much for trophy shelf queens so when my equipment shows wear and tear I just figure that's part of the territory. I understand that others feel differently so that's why I keep looking.
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

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Nemrod
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Re: Aluminum Backplate Questions

Wed Jan 29, 2020 11:28 am

Marine applications of aluminum are usually 6061. There is a place in Wicheetau (Wichita) called The Yard Store. It carries a lot of surplus from the aircraft manufacturing here (Boeing, Airbus, Cessna, Beechcraft, LeerJet and in the past Funk, Stearman, Travel Air and some others) thus being called the Air Capitol. Or at least it used to. Pickings are pretty slim these days at The Yard. But, I can usually find something there. Scrap metal prices being so high they are just scrapping everything instead of surplussing.

I have five technical plates, three of which are bare aluminum, a SS Freedom Plate and now two VDH plates. The two VDH plates, one is powder coated (wife) and one is bare (mine) and it shows very little if any corrosion. My Hammerhead plates are 6000 series aluminum I think and they also show no corrosion. I built a few prototype plates, since recycled, using 6061T6 and they did not corrode in any significant way.

FWIW
James

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captain
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Re: Aluminum Backplate Questions

Wed Jan 29, 2020 12:31 pm

5036-H32 is probably the most corrosion resistant aluminum alloy used in boat construction.
Marine grade. Medium to high strength non-heat-treatable alloy. More formable than 5083. Excellent corrosion resistance. Most often used to build boat hulls (in addition to 5052 or 6061) due to stress corrosion cracking resistance. Best alloy for salt water.
Captain

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rhwestfall
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Re: Aluminum Backplate Questions

Wed Jan 29, 2020 7:59 pm

great timing for this discussion. I just picked up a "blem" aluminum plate for the wife. It was not sealed, and she asked about getting it "painted". Been toying with the idea, but didn't know which process. This has helped. I have access to a local company that does electrostatic. Now, to see if they can do the color she wants....
Bob

No Longer Awaiting my Kraken.....

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Chris
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Re: Aluminum Backplate Questions

Sun Feb 16, 2020 5:52 pm

Happen to be standing by my tanks so I grabben a pic of my most used plate. Many many dives on it with no more than a garden hose rinse. The only spot of corrosion is where I had an over the shoulder camera mount with a stainless bolt. I asume most of that is salt buildup that would clean out if I tried. A phew spots of corrosion where I welded on it. The plate is uncoated bare aluminium.
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EWNichol
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Re: Aluminum Backplate Questions

Mon Feb 17, 2020 3:49 pm

Thanks for the input everyone! I cut a plate out of some 5052 on Friday, and I had a chance to test it Sunday. I'm not going to bother coating it.
IMG_20200214_165000955_HDR.jpg
I set it up to use a Dive Rite harness I picked up some time last year.
IMG_20200214_165331769_HDR.jpg
The fit could definitely be better. The tank band slots are too high, and the slots for routing the waist strap are too low. This made it hard to position my regulator correctly and put my weight belt in a spot that balanced me well. It also forced the top of my wing to be crammed up under the cans. Overall, it came together pretty well for a first try. I have enough material to make another once I decide exactly what I want to change.
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