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drill/tap in frames



 
 
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  #61  
Old July 11th 18, 11:46 PM posted to rec.bicycles.tech
John B. Slocomb
external usenet poster
 
Posts: 57
Default drill/tap in frames

On Wed, 11 Jul 2018 09:42:08 -0700, Jeff Liebermann
wrote:

On Tue, 10 Jul 2018 20:41:08 -0700, John B. Slocomb
wrote:

On Sat, 07 Jul 2018 12:33:38 -0700, Jeff Liebermann
wrote:

On Sat, 7 Jul 2018 11:06:52 -0400, Frank Krygowski
wrote:

This group has debated Rivnuts extensively. One poster claims nobody
should install a Rivnut unless he has access to a complete machine shop.
Others with more experience have said that the installation is easy for
anyone with normal mechanical skills.

That would be SMS (Steven Scharf) on one of his web pages:
http://nordicgroup.us/cageboss/

Since I've made a mess with all the available technologies, Rivnuts
(steel and aluminum), brazing (steel), TIG (aluminum), and epoxy glue
(plastic boss on aluminum), I'll remain neutral on the matter.

Hint: Use steel Rivnuts on steel frames, aluminum Rivnuts on aluminum
frame, and plastic straps or clamps on CF (carbon fiber).


One can only suppose that those "dumb asses: that manufacture rivnuts
deliberately make their product in a number of materials :-)


I'm not sure about the deliberate part, but yes, one can buy them in
steel or aluminum. I couldn't find any plastic or carbon fiber
rivnuts.

And, it might be added that not knowing what you are doing is not
limited to bicycle maintenence :-)


True. If those expounding on bicycle technology by various electronic
means really knew what they were doing, they would be riding instead
of pounding on the keyboard. If you really want to know how things
work, find someone that is actually doing the work and interrogate
them for the information you need and don't bother reading books,
manufacturers literature, magazines, forums, and newsgroups. The only
downside is that those who really know, tend to be inarticulate and
have difficulties explaining complex concepts, like which way to
tighten a right handed bolt. However, persistence, intimidation, and
perhaps bribery will eventually produce the required answer from a
real expert.

As I mentioned, I have successfully trashed most everything I've tried
to do with Rivnuts on bicycles, and therefore have no opinion on the
matter. However, it might be interesting to try a simple test. I
could probably finance the test by taking bets on the outcome.

Take two identical lengths of steel bicycle tubing. Install a Rivnut
in only one tube at midpoint. Clamp one end in a pipe vise. Pull on
the other end with a Come-Along perpendicular to the tubing. Measure
the force with a load cell. Draw a graph to show when the tubing went
plastic and eventually buckled. Compare results between the tubing
with and without the Rivnut. That should settle the debate whether
Rivnuts are detrimental to frame and stay strength.



(Big Smile) I know a bike builder who accidentally did just that, with
out the rivnut being installed - bending the curve into the front fork
blades with a 5 foot bar :-)

But as an aside, anything will break given sufficient force applied
which doesn't prove much of anything.
--

Cheers,

John B.
Ads
  #62  
Old July 11th 18, 11:51 PM posted to rec.bicycles.tech
SMS
external usenet poster
 
Posts: 8,299
Default drill/tap in frames

On 7/11/2018 10:18 AM, Jeff Liebermann wrote:
On Tue, 10 Jul 2018 21:25:06 -0700, John B. Slocomb
wrote:

On Mon, 09 Jul 2018 10:55:00 -0700, Jeff Liebermann
wrote:

On Mon, 9 Jul 2018 16:21:43 +0000 (UTC), David Scheidt
wrote:

sms wrote:
:On 7/7/2018 7:27 AM, Emanuel Berg wrote:
: Are there any secrets to drilling holes in
: steel bike frames? I have a couple of discarded
: ones I can test on but I thought I'd
: ask anyway.
:
: Do you use normal power hand tools like
: a drill-screwdriver and/or a drill press (if
: possible with the desired bolt position)?
:
: Do the normal rules apply, e.g. to get
: a threaded hole for an M6, you first drill with
: a 5.0mm drill?
:
: And you can use chainsaw oil, right?

:As Jobst Brandt stated: "I don't know many riders who believe that
:drilling a hole in a frame tube is a reasonable concept."

Who cares what riders think, what do the egineers do?

Jobst Brandt was a mechanical engineer.
https://en.wikipedia.org/wiki/Jobst_Brandt

What's an egineer?


One might comment that a fairly large number of bridges, that
subsequently fell down, were designed by the engineers of the times
:-)


Therefore, anything designed by an engineer will eventually fall
apart. I like the logic.

Few can recognize an
electronic problem or find someone on the design staff to blame. It's
safety through obscurity.


In chip design it's often easy to find who to blame. Actually the same
holds true in much electronic design.
  #63  
Old July 11th 18, 11:51 PM posted to rec.bicycles.tech
John B. Slocomb
external usenet poster
 
Posts: 57
Default drill/tap in frames

On Wed, 11 Jul 2018 10:18:38 -0700, Jeff Liebermann
wrote:

On Tue, 10 Jul 2018 21:25:06 -0700, John B. Slocomb
wrote:

On Mon, 09 Jul 2018 10:55:00 -0700, Jeff Liebermann
wrote:

On Mon, 9 Jul 2018 16:21:43 +0000 (UTC), David Scheidt
wrote:

sms wrote:
:On 7/7/2018 7:27 AM, Emanuel Berg wrote:
: Are there any secrets to drilling holes in
: steel bike frames? I have a couple of discarded
: ones I can test on but I thought I'd
: ask anyway.
:
: Do you use normal power hand tools like
: a drill-screwdriver and/or a drill press (if
: possible with the desired bolt position)?
:
: Do the normal rules apply, e.g. to get
: a threaded hole for an M6, you first drill with
: a 5.0mm drill?
:
: And you can use chainsaw oil, right?

:As Jobst Brandt stated: "I don't know many riders who believe that
:drilling a hole in a frame tube is a reasonable concept."

Who cares what riders think, what do the egineers do?

Jobst Brandt was a mechanical engineer.
https://en.wikipedia.org/wiki/Jobst_Brandt

What's an egineer?


One might comment that a fairly large number of bridges, that
subsequently fell down, were designed by the engineers of the times
:-)


Therefore, anything designed by an engineer will eventually fall
apart. I like the logic.


Hardly logic :-) Note the wording "engineers of the times" which is
probably more indicative of the fact that one method of gaining
knowledge is to fail, a few times :-)


The problem with mechanical engineering is that problems, such as
falling bridges, are easily visible. Even Joe Sixpack can recognize a
mechanical failure. The fault is always with the architect or
designer, and never with cost cutting contractor, sloppy construction
company, defective imported components, blind inspectors, bribed
officials, or the demands of the aesthetics committees. It's for this
reason that I chose to go into electronics. Few can recognize an
electronic problem or find someone on the design staff to blame. It's
safety through obscurity.

--

Cheers,

John B.
  #64  
Old July 12th 18, 12:52 AM posted to rec.bicycles.tech
John B. Slocomb
external usenet poster
 
Posts: 57
Default drill/tap in frames

On Wed, 11 Jul 2018 17:44:49 -0400, Frank Krygowski
wrote:

On 7/11/2018 12:25 AM, John B. Slocomb wrote:

One might comment that a fairly large number of bridges, that
subsequently fell down, were designed by the engineers of the times


Locally, the current hot problem is a historic and well-loved pedestrian
suspension bridge in a park.

One know-it-all claims he talked to one engineer who said "It's reached
the end of its useful life" and offered to design a replacement for
several thousand dollars, which would require many tens of thousands of
dollars to build. Know-it-all wanted the village to hire the guy on the
spot.

When there was skepticism, the know-it-all (a marketing guy, BTW)
brought in another engineer. Know-it-all claims this engineer said "I'd
close it immediately for safety reasons." No details from either of
those engineers on what might possibly fail. In fact, no direct
communication from them at all. All we have is know-it-all's version of
their views.


I'm not sure I'd heap all the blame on the two engineers. A casual
conversation can easily be interpreted :-)

Given that doing oil exploration in the jungles can result in a lot of
bridges being built one of out clients wanted some engineering data on
"Wooden Bridges" which in the U.S. is, apparently, difficult to find.
Luckily we hired an Australian Bloke who had worked for the Tasmania
Timber Development who are still design and building fairly good sized
wooden bridges.

Shortly after we "discovered" Tasmania one of our people in the U.S.
came across a retired guy who used rebuild wood bridges for the
railroad and he still had a bunch of reference material that we
copied.

Meanwhile another registered Professional Engineer examined it and
reported in detail, saying that there is no danger at all, that safety
factors are in the hundreds, that only minor repairs are needed, and
that those can be done by volunteers.

I'm a retired PE, and I agree with that guy. But we'll see which way the
politics go.


I've always had good luck paying for a "preliminary report" to include
recommendations. I find that most people get rather conservative when
asked to "Sign the Report".
--

Cheers,

John B.
  #65  
Old July 12th 18, 01:08 AM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 9,629
Default drill/tap in frames

On 7/11/2018 5:39 PM, sms wrote:
On 7/11/2018 11:42 AM, Emanuel Berg wrote:
Joy Beeson wrote:

I put it there with cable ties ("wires") but
there was an annoying sound while riding
the bike.

You need a hose clamp. Wrap the tube with
handlebar tape to protect the paint. Also,
clamp on tape has a much higher co-efficient
of friction than clamp on hard surface.

I attached two bottle cages this way late in
the twentieth century, and haven't thought
about them since.


Good idea, I'll try that next. The hose clamp
is an underrated commodity when it comes
to bikes.


No it's not. It's an over-rated kludge.


Had you said 'inelegant' I would agree with you.

But, like Joerg's headset clamp, functional. I've seen many
ugly but workable stainless hose clamp repairs/upgrades on
customers' bikes over the years but never a broken one.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #66  
Old July 12th 18, 04:16 AM posted to rec.bicycles.tech
Jeff Liebermann
external usenet poster
 
Posts: 2,832
Default drill/tap in frames

On Wed, 11 Jul 2018 13:48:47 -0500, AMuzi wrote:

I think the question isn't so much 'has the tube's ultimate
strength been diminished?' but rather 'is it yet strong
enough for expected application?'.


Nope. I'm not trying to measure if the tubing is strong enough.
Assuming identical lengths of tubing, I wanted to see if the presence
of a Rivnut significantly changed the tension required to bend or
break the tubing when compared to the identical tubing that did not
have a Rivnut inserted. If I'm able to pull hard enough, I should be
able to eventually break both tubes. If they break at the same
tension, then I'll declare the Rivnuts are safe to use. If there's a
substantial difference in tension, then I'll declare the Rivnuts
weaken the frame.

In theory and in absolute yes the tube is less strong. In
practice, from Santana ExoGrid tandems to Bianchi thinwall
tempered aluminum models, to their carbon bikes, rivnuts are
not a failure point.


Where are the Rivnuts installed on these machines? Water bottle
holders? The pictures don't show much detail:
https://www.google.com/search?q=Santana+ExoGrid+tandem&tbm=isch&
https://www.google.com/search?tbm=isch&q=bianchi+aluminum


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #67  
Old July 12th 18, 04:20 AM posted to rec.bicycles.tech
Jeff Liebermann
external usenet poster
 
Posts: 2,832
Default drill/tap in frames

On Wed, 11 Jul 2018 15:46:28 -0700, John B. Slocomb
wrote:

(Big Smile) I know a bike builder who accidentally did just that, with
out the rivnut being installed - bending the curve into the front fork
blades with a 5 foot bar :-)


I think that's called a "torque amplifier".

But as an aside, anything will break given sufficient force applied
which doesn't prove much of anything.


Ah, but if there's a significant difference in tension (force) between
the tube with and without a Rivnut, then methinks it demonstrates that
Rivnuts weaken the frame. I think the real trick will be to find two
tubing pieces that are really identical. I'll check with the local
"Bike Church" to see if they have any old frames laying around. I
have a few frames, but I didn't want to trash them quite yet.



--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #68  
Old July 12th 18, 04:43 AM posted to rec.bicycles.tech
Jeff Liebermann
external usenet poster
 
Posts: 2,832
Default drill/tap in frames

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.

Maybe this will work:
http://structural-analyser.com
Nope. Won't do tubing.

And BTW, the test you're describing would be much, much easier to do in
a proper tensile testing machine. Find an engineering student, get him
interested, have him get permission to do it as a class project, and
your data would be much better.


Yep, but my use of UCSC equipment has turned into a complex hassle.
I'll spare you the details, but at this time, it's not an easy
options.

I was wondering how I would do it on a proper machine. Probably
support the tube at the ends and push in the middle behind the Rivnut.
The problem with that is I'll probably crimp the tube where it's
pushing. It's likely I'll tear the tube before it bends. So, I'm
stuck with securing one end, and pulling (or pushing) on the other.

But on the other hand, tensile strength of the tube isn't really the
concern. The concern would be fatigue strength, and if we're talking
about the down tube, it would be under repeated, reversing torsional
stresses.


Good point. However, it will take too many tubing samples to test all
the possible combinations of forces available. Shall we keep it
simple and just bend a tube or two?

I strongly suspect that you'd find no significant difference. One
feature of the Rivnut is that its clamping action on the parent metal
applies compressive stress. Fatigue cracks start in regions of tensile
stress. The Rivnut may even make the object stronger.


Clamping action requires equal compression at all points around the
Rivnut hole. That's not going to happen in tubing where the Rivnut is
being crimped onto a curved surface. At the peak of the curve, there
will probably be plenty of compression force holding the Rivnut in
place. 90 degrees to either side, there may be an air gap with zero
compression force. In order to make it stronger on the curved surface
of the tubing stronger, the Rivnut would need a matching curve.


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #69  
Old July 12th 18, 07:56 AM posted to rec.bicycles.tech
SMS
external usenet poster
 
Posts: 8,299
Default drill/tap in frames

On 7/11/2018 5:08 PM, AMuzi wrote:
On 7/11/2018 5:39 PM, sms wrote:
On 7/11/2018 11:42 AM, Emanuel Berg wrote:
Joy Beeson wrote:

I put it there with cable ties ("wires") but
there was an annoying sound while riding
the bike.

You need a hose clamp. Wrap the tube with
handlebar tape to protect the paint. Also,
clamp on tape has a much higher co-efficient
of friction than clamp on hard surface.

I attached two bottle cages this way late in
the twentieth century, and haven't thought
about them since.

Good idea, I'll try that next. The hose clamp
is an underrated commodity when it comes
to bikes.


No it's not. It's an over-rated kludge.


Had you said 'inelegant' I would agree with you.

But, like Joerg's headset clamp, functional. I've seen many ugly but
workable stainless hose clamp repairs/upgrades on customers' bikes over
the years but never a broken one.


Inelegant in some cases, kludge in some cases. There is almost always a
more elegant, simple, minimalist solution. Maybe not as cheap though.

http://www.minoura.jp/english/accessory-e/bh95x-e.html
http://www.minoura.jp/english/accessory-e/lw-e.html
https://www.amazon.com/dp/B00OS6HKIM
http://www.zefal.com/en/bottle-cages-thermoplastic/60-gizmo-universal.html

  #70  
Old July 12th 18, 08:01 AM posted to rec.bicycles.tech
SMS
external usenet poster
 
Posts: 8,299
Default drill/tap in frames

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.
 




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