Structural Engineering: Re: Aluminum Lag Bolts

Gerard,

Your situation is fairly common in the construction of aluminum frame skylights and curtain walls. Granted these connection are not generally directly exposed to the elements but normally we
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seaint Digest for 23 Jun 2007

Topics covered in this issue include:

1: Re: Aluminum Lag Bolts
by "Gerard Madden, SE" <gmse4603@gmail.com>

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1 Message:0001 1
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From: "Gerard Madden, SE" <gmse4603@gmail.com>
To: seaint@seaint.org
Subject: Re: Aluminum Lag Bolts

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Thanks Bob and Chris!

The project is in San Jose, Ca. The aluminum is not anodized to my
knowledge.

I appreciate your help gentlemen!

-gm

On 6/22/07, Robert Kazanjy <rkazanjy@gmail.com> wrote:
>
> 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.
>
>
> cheers
> Bob
>
>
>
> On 6/22/07, Gerard Madden, SE <gmse4603@gmail.com> 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.
> > --
> > -gm
>
>
>

--
-gm

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Thanks Bob and Chris! The project is in San Jose, Ca. The aluminum is not anodized to my knowledge. I appreciate your help gentlemen! -gm <div>On 6/22/07, 
Robert Kazanjy <<a href="mailto:rkazanjy@gmail.com">rkazanjy@gmail.com</a>> wrote:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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. cheers Bob<div> <div>
On 6/22/07, 
Gerard Madden, SE <<a href="mailto:gmse4603@gmail.com" target="_blank" onclick="return top.js.OpenExtLink(window,event,this)">gmse4603@gmail.com</a>> wrote:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">

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. -- -gm
</blockquote></div> 
</div></blockquote></div> -- -gm

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Sunday, June 24, 2007

Re: Aluminum Lag Bolts