Best hold in thin alumium?

I have a problem holding thin aluminum, about .080", together for a period of 3 - 4 months in an outdoor environment. I have tried drilling and taping with # 8, 10, 12,
fine & course thread machine bolts, which last a few cycles then strip out. The force needed is about 3 - 5 lb compression. I only have limited access to one side of the joint. I'm now thinking of a finer thread screw such as drywall screws which are designed for metal studs. Any thoughts or suggestions?? To reply to this message please remove the AT after the kgs1 in the reply to address. To a conservatist's it truly is a free country, YOU may do whatever they wish. KG
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On 10/22/2013 10:22 AM, KG wrote:

Wonder if pop rivets would work? Aluminum rivets, you can shear the head off with hammer and chisel, later. Push the rest of the rivet through.
Or, use threaded inserts? Jack nuts?
. Christopher A. Young Learn about Jesus www.lds.org .
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NO....! You just gently counter-drill in the hole, and it falls right off!
Lloyd
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> fired this volley in
Besides, There are some dandy blind nuts which fit in an oversized hole, and expand on the back-side of the metal the first time you torque the screw down.
Lloyd
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On 10/22/2013 10:52 AM, Lloyd E. Sponenburgh wrote:

Or, use threaded inserts? Jack nuts? (what I said a few minutes ago....)
. Christopher A. Young Learn about Jesus www.lds.org .
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'Expanding blind nuts' ARE threaded inserts, but they're designed to fit snugly in a hole (sometimes knurled to press in tightly), then when the screw is torqued, they expand on the back-side of the work to prevent them from being pulled out front-wise.
Most of them are designed to work flush to to bolting surface, so they don't interfere with a close fit. They're not 'free', but they're not expensive, nor difficult to install.
Lloyd
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On 10/22/2013 10:50 AM, Lloyd E. Sponenburgh wrote:

YES ...! That sounds like what a machinist would do.
. Christopher A. Young Learn about Jesus www.lds.org .
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Stormin Mormon wrote:

I'd second the idea of pop rivets. If you need something stronger than hardware store rivets, you could use Cherry aircraft rivets.
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wrote:

Or just go up one size with the pops.
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snipped-for-privacy@snyder.on.ca fired this volley in

Hasn't anyone noticed that he wishes to disassemble this thing from time to time? C'mon! Pop Rivets need to be drilled out. How about flush expanding nuts?
Lloyd
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On Tue, 22 Oct 2013 17:00:19 -0500, "Lloyd E. Sponenburgh"

He didn't say it had to come apart - only that it needed to hold for a number of months. If it needs to come apart he should install Dzuz (1/4 turn) fasteners.
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snipped-for-privacy@snyder.on.ca fired this volley in

Yes, he did. And they require a "receiver" as well.
Lloyd
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On Tue, 22 Oct 2013 19:25:57 -0500, "Lloyd E. Sponenburgh"

All part of the fastener - of course.
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On Tue, 22 Oct 2013 19:25:57 -0500, "Lloyd E. Sponenburgh"

Where in "I have a problem holding thin aluminum, about .080", together for a period of 3 - 4 months in an outdoor environment." did it say it needed to come apart? or how often? He just said it needed to stay together for 3 to 4 months - which his method was not doing. If he gave us an idea of the application we could give him an intelligent solution. He says he only needs 4-5 lbs force but does not tell us what shear strength he needs. He did not say how often it needs to come apart and go together either. Mabee a latch, like a Dzuz is required. Mabee a riveted on piano hinge with a removeable wire would be the proper solution. Mabee it should have a thick bar fastened to the back of the back sheet, threaded for bolts or machine screws. If the holes are near an edge, mabee he should use tinnermans. Mabee he should rivet on nut-plates.
If it only needs to stay together for up to 4 months, once, nothing wrong with pop-rivets - either use backing washers, or just use enough that they hold - do like Zenith Aircraft does - use 50% more than you might possibly need for the calculated forces. (he uses avdels - which are really just "super pop-rivets" and not NEARLY as expensive as Cherries)
Different horses for different courses - and we have NO idea what his application or requirements really are.
(and he DID say he "taped" the screws into the metal - what kind of tape did he use - mabee better tape would do the job - I ASUME he meant he TAPPED them. - but that's not what he said - - - - )
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snipped-for-privacy@snyder.on.ca fired this volley in

"I have a problem holding thin aluminum, about .080", together for a period of 3 - 4 months in an outdoor environment. I have tried drilling and taping with # 8, 10, 12, fine & course thread machine bolts, WHICH LAST A FEW CYCLES THEN STRIP OUT."
I guess you're so intent on defending your position that you ignored the last part of his statement.
You critcize his spelling, but make your own redactions of his words to fit your meaning?
Lloyd    
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote:

Cycles of WHAT? Assembly/disassembly, or thermal cycles? I can easily imagine either interpretation.
Yes, without using an anti-seize coating, I can imagine #8 screws in .080" sheet would be pretty fragile in continuous outdoor exposure.
Jon
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On Tue, 22 Oct 2013 23:00:35 -0400, snipped-for-privacy@snyder.on.ca wrote:

************************************* Further information
The aluminum is two 1/1.7" enclosed extrusions which need to be held together till spring, then totally free to move back and forth across each other until the next winter. We live on the Great Lakes and they are storm doors for 70 feet of sliding glass windows walls, kg To reply to this message please remove the AT after the kgs1 in the reply to address. To a conservatist's it truly is a free country, YOU may do whatever they wish. KG
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KG wrote:

Well, tapping #8 holes into extruded aluminum that is outdoors full-time is not going to last. There is corrosion, and daily solar heating that works the panels against what is under them. Some kind of fitting with ability for the panels to slide a bit will help. The mention of Dzus fasteners is a good one, they are used lots on aircraft for this reason (corrosion + thermal cycling) and have stood up well over probably 80 years, now. But, not as easy to install, as you need unrestricted access to the rear part to install the fastener. There are lots of outfits that make specialty fasteners for aluminum things, possibly looking at the Thomas register will give you some leads.
Using liberal amounts of an anti-seize coating on the screws might prolong the life of the threads in the rear part. Also, there may be a screw material that is optimal for use in aluminum, some steel and stainless screws make the corrosion MUCH worse, and the threads will gall massively the first time the screw is removed.
Jon
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KG wrote:

How about an internal expanding rubber plug? Like a boat drain plug but smaller. 1/4" or smaller rubber tubing on a small screw with a washer and nut to draw down and bulge the rubber. Use stainless or bronze for the screws and it shouldn't corrode. Put plug in hole, tighten nut to expand rubber. You could even get fancy and use countersunk heads to ensure expansion.
--
Steve W.

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wrote:

I take it this is two door panels sliding past each other? The two extrusions "move back and forth across each other " when the panels move - what's wrong with going through BOTH sides of BOTH extrusions and putting in a pin????
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