Fastener puzzle

I've been trying to figure out the best way to do this for a few weeks
now, and I haven't come up with anything I like yet. I'm working on a
product where 4 pieces of 1/4" round aluminum need to be able to screw
onto four sides of both 1 1/2" OD aluminum tube and 2" OD tube. Both
tubes are .065. Picture a hat rack with the large tube being the
center, but that's not what it is. These parts will be assembled by
the buyer, so it has to be simple, and yes, it does have to be in
separate parts... it can't be welded. Having nuts welded onto the
inside of the tube would probably be best, but the tube is too long to
do that. The best I can come up with is to just send a 4-40 machine
screw all the way through the tube and two pieces of 1/4" at a time,
and put a nut on the opposite side, but the proper lengths for the
screws to do that don't seem to be standard in 4-40 size. It would be
great to figure out a way to screw the rounds directly to each four
sides of the center tube, but I can't think of a way to do it.
Any mechanical geniuses have a good idea?
Reply to
Dave99
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You're talking about square tubing, right?
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Either screw your 1/4" Al to suit or drill for a screw fastener and use the appropriate Rivnuts.
Tom
Reply to
Tom
This is a product that you intend to sell for profit, right? I missed the part where you mention how you'd compensate one or those who provides you with the idea(s) you profitably use.
Reply to
Don Foreman
Countersunk Rivnuts?
Reply to
Steve W.
rubber Wellnuts (TM)?
Reply to
Den
On Tue, 22 Apr 2008 21:44:21 -0700 (PDT), with neither quill nor qualm, Dave99 quickly quoth:
Pemnuts should do the trick for you, Dave.
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catalog page 3150
-- Happiness in marriage is entirely a matter of chance. If the dispositions of the parties are ever so well known to each other or ever so similar beforehand, it does not advance their felicity in the least. They always continue to grow sufficiently unlike afterwards to have their share of vexation; and it is better to know as little as possible of the defects of the person with whom you are to pass your life. -- Jane Austen, Pride and Prejudice, 1811
Reply to
Larry Jaques
On Tue, 22 Apr 2008 21:44:21 -0700 (PDT), with neither quill nor qualm, Dave99 quickly quoth:
Oops, I forgot one. I used to use one of these to put nuts in truck doors for permanent mounting of large trailer mirrors.
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-- Happiness in marriage is entirely a matter of chance. If the dispositions of the parties are ever so well known to each other or ever so similar beforehand, it does not advance their felicity in the least. They always continue to grow sufficiently unlike afterwards to have their share of vexation; and it is better to know as little as possible of the defects of the person with whom you are to pass your life. -- Jane Austen, Pride and Prejudice, 1811
Reply to
Larry Jaques
Those are all great ideas guys, thanks a lot. I knew there had to be something like that, but I couldn't find it. Sorry, I forgot to mention that this is round tube for the center, not square. But I would think one of these would still work though, right? Since it's just a 4-40 size, the heads won't be that big on the round tube.
Dave
Reply to
Dave99
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That is what I would suggest, too. It helps to have the right tooling, of course. The larger steel ones want hydraulic pullers, but for aluminum ones (the most common), try ebay for the tooling:
320242645479 10-32 puller. (Called a "speed tool") 290223988051 100 10-32 Rivnuts. Grip range .010 to .075 inch.
Scroll down to see what an un-set Rivnut looks like. It expands in the middle to grip the sheet metal from the inside, and leaves a threaded section beyond that.
320242645759 8-32 puller. (Called a "speed tool")
190216705352 Three sizes -- but they don't say which sizes. :-( Also called a "speed tool"
300218570212 Pneumatic powered -- expensive, but if you're doing serious production it might be worth while. This one is 6-32.
310043802502 Same, but 10-32.
(there are also 4mm and 6mm ones)
190217110740 Cheap, but you don't want this style if you have a choice These are slow and clumsy.
My ebay search string is designed to skip a bunch of things which I did not want when I was looking for these, and it seems to turn up a pretty clean search still:
rivnut* -damper -"reference cd" -cessna -helmet -"belly pan" -ford -raover -"cad plated aircraft grade bolts"
Note that for some Rivnuts there is a key on the underside of the flange, and there is a separate tool for notching the hole for the key to keep it from spinning inside the hole. It also has an angled handle like the speed tool, but does not have the mushroom shaped handle to pull out and in to spin the threaded arbor for the Rivnuts. This part is where the "speed" come from. The tool has to be adjusted to a specific set of Rivnuts and thickness of metal, but after that it is every easy to use. Don't adjust it, and you can strip the threads out of the Rivnuts.
Good Luck, DoN.
Reply to
DoN. Nichols

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