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Old July 11th 18, 11:29 PM posted to rec.bicycles.tech
John B. Slocomb
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Posts: 547
Default drill/tap in frames

On Wed, 11 Jul 2018 07:42:26 -0700, sms
wrote:

On 7/9/2018 11:16 AM, David Scheidt wrote:

he was also wrong about many things. Every bike I've ever had has had
holes drilled in it. Clearly, there is a range of holes that do not
cause failure, and some that do. The question is where does a rivnut
fall? I wouldn't drill a 5 mm hole a on 26mm diameter tube, but they
work fine on large diamter ones.


Did you drill those holes and install the Rivnuts or did they come from
the factory that way. Were these steel or aluminum tubes?

Rivnuts in very thin tubing need to be installed very carefully. Drill
them with the wrong drill and you'll crack the tubing. Install them too
loose and they'll spin. Install them too tight and they cause cracking.

You can get away with doing this but it doesn't mean that it's a good
idea. There's a reason why all the experts advise against doing this,
and why it voids the frame warranty (if you're the original owner with a
lifetime warranty, you might worry about this).


Err.... Crack the tubing? How so? Is there some sort of magic here?
Drill a hole a tiny bit larger then optimum and CRACK! The tube
cracks?

You just seem to delight in telling us just how little you know about
what you are talking about.

As you also obviously know little about rivnuts you might be
interested in knowing that the Rivnut people are very explicit in
specifying dimensions and even how tight to compress them when
installing them. See:
https://www.google.com/search?tbm=is...i h=660&dpr=1
for some examples.

Searching for "rivnut+specification" will return some 65,000 hits
specifying all kinds of information useful to the embryo rivnut
installer. And even to the experienced.

Given that the rivnut company has published their installation data
for you to read. Read it. You don't have to be a dumb ass.


For those determined to do this, look into the Plusnut (made by Rivnut)
which is more suitable for end-user applications.


Why do you say that? After all Rivnut advocates their Plusnuts as
"Ideal for plastics and thin sheet metal applications where ultimate
pull-out strength is required." Have you seen a lot of rivnuts ripped
out of the frame tubes by sheer force?

For the OP, is the chainstay even a large enough diameter for a Rivnut?

What might work is using M3 x 0.25 screws. You'd have enough threads for
a 1 mm thick tube. Both the screws and the taps are not cheap as these
are used on high-precision machinery. Tthey also have M6 x 0.25, but I
did not see any M5.


--

Cheers,

John B.
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