Best hold in thin alumium?

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

Stormin Mormon fired this volley in news:14w9u.61461$ snipped-for-privacy@fx28.iad:

NO....! You just gently counter-drill in the hole, and it falls right off!

Lloyd

"Lloyd E. Sponenburgh" fired this volley in news:XnsA2616E5054A87lloydspmindspringcom@216.168.3.70:

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

What's wrong with a big honing rivet??? The limited access allow you to get a backing washer on the rivet? If so you can use Monel or stainless rivets with washers on both sides to spread the load. A sheet metal screw of ANY description is just trouble waiting to happen.

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

Rivets. Need to remove? Rivnut one, and screw the other.

YES ...! That sounds like what a machinist would do.

. Christopher A. Young Learn about Jesus

Or, use threaded inserts? Jack nuts? (what I said a few minutes ago....)

. Christopher A. Young Learn about Jesus

Try using a punched hole, like from an awl. The dimpled out material on the back side gives you a lot more material for your screw to bite into.

There used to be special punch sets made for this. They had a sharp point with different sized shafts leading to a shoulder so you didn't have to guess at how far to run your punch in.

Stormin Mormon fired this volley in news:g2A9u.26371$ snipped-for-privacy@fx05.iad:

'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

Or just go up one size with the pops.

Have you tried roll (thread-forming) taps? They have the advantage of forming threads by displacing metal, so the threads are somewhat more hardened than you get from thread-cutting taps. Beware that the tap drill for roll taps is a different size from thread-cutting taps, and a much more critical size as well.

If there is space behind the plate, another option might be Rivnuts. They fit into a drilled (and countersunk if need be) hole, are drawn somewhat like pop rivets, and provide a much longer thread.

Also -- since this is in the outdoors (and I presume an area where rain is common, rather than a desert area), you will need to consider the effects of different metals in contact in a wet environment. So perhaps you should look into self-tapping aluminum screws instead of steel. (Not sure what the results would be with brass screws in aluminum instead, but it might be worth checking out.)

Good Luck, DoN.

snipped-for-privacy@snyder.on.ca fired this volley in news: snipped-for-privacy@4ax.com:

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

An in between solution I have heard of (in this group actually) is to punch the hole in the bottom sheet. This creates an elongated cone and allows for more threads to tap.

_____________________ ______......____________ \ /

I think if you found the ideal punch it would have a straight shaft of the appropriate diameter with a hardened long conical point, and maybe a stop to avoid over driving.

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.

snipped-for-privacy@snyder.on.ca fired this volley in news: snipped-for-privacy@4ax.com:

Yes, he did. And they require a "receiver" as well.

Lloyd

I don't know how much room there is on the "back sides" but you might try Rivnuts which are a sort of threaded pop rivet. You can install the rivnut from one side of your sheetmetal and then use a bolt to hold things together.

Lloyd, where is the part which says he wants to take them apart?

I bought one of the HF gun kits and used it on my '91 F-150 doors to hold the trailer mirrors on. Worked like champs for years, and AFAIK, are still working. For $17, you cannot go wrong. Maybe he can use one of them.

Anti-seize is cheap.

All part of the fastener - of course.