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Re: Aluminum Lag Bolts

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Where is the job site? Is the aluminum hardware anodized or just plain?

I do not remember the specification or material exactly but in aerospace apps  using SS fasteners with aluminum "skins" where the anodizing had been machined away (drilling for rivet or countersinking for flat head screw installation)  required the use of a zinc chromate primer ....I'm going from memory of work done in the late 80's

In any case, people have been attaching aluminum objects to other objects (wood, aluminum, SS) for years and most of the time do not spec (like never) aluminum fasteners.

In your particular installation I would suggest you consider good quality heavy hot dipped galvanized steel lag & heavy hot dipped galvanized

OR SS lags with the zinc chromate primer "dance" or a flanged bushing to handle the head & shaft contact.


On 6/22/07, Gerard Madden, SE <gmse4603(--nospam--at)> wrote:
Is there such a thing?

I need to fasten some aluminum to the exterior of a wood frame building and don't want to use steel lags or stainless steel lags due to dis-similar metals. Its a wood framed stud wall with plywood sheathing, then the aluminum right up against the sheathing. Need to lag into the wall studs. A 3/8" carbon steel lag about 4" long would work by calc.

I know I can put neoprene washers under the head of the lag, but the bearing of the shaft on the hole in the aluminum seems to be an unavoidable contact point.

I asked something similar a few months back, got a lot of helpful replies, but this project has surfaced again and need to figure out this connection.

I've browsed the web and found places that make aluminum screws of very small diameters but seem to be for sheet metal applications. But this can't be the first time in engineering history someone wanted to connect decorative aluminum to a wood building. :-)

any help is appreciated.