In article ,
Robert Swinney wrote:
"Leo Lichtman" wrote in message
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[ ... ]
I agree. Furthermore, after they have been removed and retightened a few
times, the holes will begin to enlarge, and possibly release. Threaded
pop-rivets might be an easy way to make the threaded holes.
Please explain a bit about threaded pop-rivets. I've not heard of them. Do
they leave a threaded nut on one side, or a threaded screw; or maybe a
threaded member on each side.
Not really pop-rivets. what you want are called "Rivnuts".
They fit in from the near side, and the tool draws the threaded far
side towards the near side, expanding a section in between. They often
have a rib which gets oriented in a notch cut from the hole to prevent
rotation if you don't pull it down tight enough.
You *can* pull them down with a stud in a pop-rivet tool,
thought there are much better tools for the purpose.
You can find some sizes at MSC, and perhaps some tooling, but I
go to eBay for this.
Here is an auction which has some steel Rivnuts in several
metric sizes:
Auction #3880108987
and here are some mo
Auction #4534138893
They come also in aluminum, typically with a greenish finish, though I
have seen plain aluminum. Here are some of them:
Auction #3879123472
As for the tooling to install them -- here is an example of the
kind which I prefer:
Auction #3880590104
Pull out on the mushroom head on the end of the handle, hold the Rivnut
on the screw at the other end, and push the mushroom back. This will
run the screw up inside the Rivnut. Place the Rivnut in the hole
(orienting it properly if there is an anti-rotation rib) and squeeze the
handle to set the nut. Then pull on the mushroom again to unscrew the
tool from the Rivnut. (Note that for a given size of Rivnut, a given
grip range, and a given thickness of sheet metal, you have to adjust
the threaded sections of the nose anvil to get it so it sets properly --
not too loose, and *especially* not too tight, which can rip out the
threads from the inside. With experience, you can develop a feel so you
won't strip them without adjusting, but this is meant as a production
tool (though there are air-powered tools for faster production), so it
can be set so the full squeeze does it right.
Each one of these is for a single size, so be sure to get the
one to match the screw size which you wish to use -- or collect them
all. That particular style ranges from 4-40 through 1-4/20, along with
a corresponding set of metric ones, which are much less common.
There are similar tools (tubular handle with lever to actuate)
which will notch for the orientation/anti-rotation ridge. They will not
have a mushroom handle, and they, also, will be for a specific size.
You *can* rebuil these for different sizes with kits of parts,
but I find it more convenient to have one of each size on hand.
There is a smaller one which is drawn up with a wrench, but it
does not appear in my searches today. I have a few of these (6-32,
8-32, and 10-32 IIRC) for use where there is not room for the
mushroom-handled tools -- but they are slower.
The air-driven one looks really nice at the moment, but it has
over six days to go, and already has several bids. :-)
I also have a hand-pumped hydraulic one, for pulling up the
larger steel Rivnuts.
However -- there are cheaper designs, which I personally would
avoid, which show up regularly. Here is an example of what I avoid:
Auction #4533826680
Note that I have no financial interest in any of these auctions,
though I may have purchased from some of the vendors in the past.
Good Luck,
DoN.
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