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Old July 12th 18, 09:50 PM posted to rec.bicycles.tech
JBeattie
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Posts: 5,870
Default drill/tap in frames

On Thursday, July 12, 2018 at 1:06:52 PM UTC-7, AMuzi wrote:
On 7/12/2018 1:46 PM, Duane wrote:
On 12/07/2018 12:50 PM, AMuzi wrote:
On 7/12/2018 11:26 AM, Frank Krygowski wrote:
On 7/12/2018 3:01 AM, sms wrote:
On 7/11/2018 8:43 PM, Jeff Liebermann wrote:
On Wed, 11 Jul 2018 17:24:40 -0400, Frank Krygowski
wrote:


Exactly. Strong enough is strong enough.

OK, so let's pretend that the tube with the Rivnut bent
at 10% less
tension. Is that "strong enough"? There's no
way to
tell without the
original design calculations, or reverse engineering the
frame with an
FEA model. Too bad Autodesk killed their online
ForceEffect web app.
http://blogs.autodesk.com/inventor/2017/01/17/autodesk-forceeffect-family-retirement/


I think I could have modeled the problem using the
program.

It's a bad experiment because it doesn't take into account
whether or not the hole was properly drilled and the
Rivnut properly installed. You also have to do it with the
same aluminum tubing used on a bicycle frame, but even
then it isn't accurate because there's no way to factor in
metal fatigue which isn't an issue as much in steel as it
is in aluminum.

Remember, just because you can often get away with doing a
really stupid thing, it doesn't mean that you should still
do it.

Remember, just because one person declares a practice to be
stupid, it doesn't mean the practice really is stupid.

In fact, if the practice (like the use of Rivnuts) is
generally very successful, the stupidity probably lies
elsewhere.


Goes both ways. Sometimes, the crowd looks to The Left
while visionaries look Right:

https://www.zerohedge.com/sites/defa...0nato%204..jpg



Or maybe some people only look right, even when it's the
wrong direction...


Yes as I noted, goes both ways.
As Chou En Lai said of the effects of the French Revolution,
it's too soon to say.


Crowd logic makes little difference when it comes to calculating material strength -- it's not like Trek puts its frames in a crowd and asks for opinions on the number of fatigue cycles it will withstand. It tends to use test fixtures. https://www.youtube.com/watch?v=tT4yS5wTkY0 A qualified engineer could opine on whether rivnuts are good or bad for a particular application. It's not like the prophet SMS versus the blind rivnut believers!

And the effects of the French Revolution were pretty easy to evaluate for Louis XVI. No mystery there, and living in a Blue State, the effect of Trump policy choices are immediately apparent, e.g. capped deduction for state taxes, pardoning dopes who burn public land, etc., etc. I don't need to wait 200 years to figure this one out. I'm being punished because my state voted "wrong."

-- Jay Beattie.

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