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drill/tap in frames



 
 
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  #121  
Old July 14th 18, 02:23 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 9,484
Default drill/tap in frames

On 7/14/2018 2:01 AM, John B Slocomb wrote:
On Fri, 13 Jul 2018 20:53:33 -0500, AMuzi wrote:

On 7/13/2018 8:14 PM, Ralph Barone wrote:
John B. Slocomb wrote:
On Fri, 13 Jul 2018 12:49:33 +0000 (UTC), Ralph Barone
wrote:

John B. Slocomb wrote:
On Fri, 13 Jul 2018 00:10:02 +0200, Emanuel Berg
wrote:

James wrote:

Then you should definitely not just drill
and tap the frame tube itself.

Why not?

The material is too thin.

Is it more thick at the bottom of the bottom
bracket shell and at the bottom-mid section of
the down tube where I have seen this numerous
times, and also the chainguard stays to the
chainguard intersection?

A bottom bracket is usually specified as 7 - 8 mm thick.
--

Cheers,

John B.


Maybe 3-4 mm. Are you quoting the difference between the OD and ID, or the
wall thickness?

I just looked at their catalog which red, for example:
"LB100R - For 22.2mm Chainstays. 60.30x62.30x7\ufffd.
No guides or cut-outs".
or
"LB109R - With Oval 30x17mm. Chainstays.
Angles 60x64x7.30\ufffd. No guides or cut-outs."

Given that the first two numbers were obviously length and breadth
assumed the last was thickness. Not so?



I don't know. I just thought that 7mm wall thickness for a bottom bracket
shell appeared to be overkill to me. I did some web searching and nobody
publishes data on the OD of bottom bracket shells (probably because it
doesn't matter to a first approximation). However, looking through a bunch
of diagrams, I did see that many of them had a 7mm deep pocket to hold the
bearings. Perhaps that's where your 7 came from.

Aha! This BB shell has a 38 mm OD and a 1.370" ID, which gives about 2mm
wall thickness.
https://framebuildersupply.com/produ...od-made-in-usa



Say that again, slowly. The O.D. is 38mm and th I.D. is 1.370??

Just measured a cast 1982 Cinelli and an unknown vendor on a
1978 Bianchi Superleggera at 3mm. Both are m36x24 on
vintage frames being repaired.

A new mid-1970s RFG pressed shell is 3mm. A new 1976 Nikko
Sangyo pressed shell is 4mm but heavy and klunky in other
aspects as well. Both 1.370"x24.

That's a quick check with a vernier so depending on your
purpose you might subtract thread depth. Or not. Regarding
threaded holes, I've seen a lot of drilling, piercing,
slots, tapped holes and so on on every kind of steel BB
without notable failure attributable to that. They do break,
just not from holes in the bottom. Classic British bikes
have a coarse threaded hole on top LH for a bearing oiler.
Cracks don't form around those either.


Say that again, slowly. The O.D. is 38mm and th I.D. is

1.370??

That would be 38mm overall, 34.8mm at thread peaks or ~33.8
at thread root leaving about 4+mm dia or 2+mm at the radius
theoretically. Which comports roughly with actual
measurements yesterday. Surely not 7mm on any modern (not
cast iron) threaded BB shell.



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


Ads
  #122  
Old July 14th 18, 04:52 PM posted to rec.bicycles.tech
Theodore Heise[_2_]
external usenet poster
 
Posts: 55
Default drill/tap in frames

On Sat, 14 Jul 2018 08:23:09 -0500,
AMuzi wrote:
On 7/14/2018 2:01 AM, John B Slocomb wrote:
On Fri, 13 Jul 2018 20:53:33 -0500, AMuzi wrote:
On 7/13/2018 8:14 PM, Ralph Barone wrote:
John B. Slocomb wrote:
On Fri, 13 Jul 2018 12:49:33 +0000 (UTC), Ralph Barone wrote:
John B. Slocomb wrote:


A bottom bracket is usually specified as 7 - 8 mm thick.


Maybe 3-4 mm. Are you quoting the difference between the
OD and ID, or the wall thickness?

I just looked at their catalog which red, for example:
"LB100R - For 22.2mm Chainstays. 60.30x62.30x7\ufffd.
No guides or cut-outs".
or
"LB109R - With Oval 30x17mm. Chainstays.
Angles 60x64x7.30\ufffd. No guides or cut-outs."

Given that the first two numbers were obviously length and
breadth assumed the last was thickness. Not so?


I don't know. I just thought that 7mm wall thickness for a
bottom bracket shell appeared to be overkill to me. I did
some web searching and nobody publishes data on the OD of
bottom bracket shells (probably because it doesn't matter to
a first approximation). However, looking through a bunch of
diagrams, I did see that many of them had a 7mm deep pocket
to hold the bearings. Perhaps that's where your 7 came from.

Aha! This BB shell has a 38 mm OD and a 1.370" ID, which
gives about 2mm wall thickness.
https://framebuildersupply.com/produ...od-made-in-usa


Say that again, slowly. The O.D. is 38mm and th I.D. is 1.370??


The I.D. is given in inches, so the two dimensions definitely look
odd together.


That would be 38mm overall, 34.8mm at thread peaks or ~33.8 at
thread root leaving about 4+mm dia or 2+mm at the radius
theoretically. Which comports roughly with actual measurements
yesterday. Surely not 7mm on any modern (not cast iron)
threaded BB shell.


I suppose it's possible that tandem bottom bracket shells can be
thinner walled because the eccentric provides some strength, but
somehow I doubt they actually are.

At any rate, I just measured (roughly) the wall thickness of my
two tandem BB shells and the 1986 Rodriguez (aluminum) is about 4
mm, and the 2012 Santana (titanium) is somewhat less--maybe 3.5
mm.

Relating to the original topic, neither has any holes drilled in
the seat stays or the chain stays. The Santana has some kind of
reinforcement (maybe like the Rivnuts that have been discussed?)
at the water bottle cage holes in the frame tubes (down tube and
both laterals).

--
Ted Heise West Lafayette, IN, USA
  #123  
Old July 15th 18, 02:48 AM posted to rec.bicycles.tech
john B [email protected]
external usenet poster
 
Posts: 1
Default drill/tap in frames

On Sat, 14 Jul 2018 15:52:39 +0000 (UTC), Theodore Heise
wrote:

On Sat, 14 Jul 2018 08:23:09 -0500,
AMuzi wrote:
On 7/14/2018 2:01 AM, John B Slocomb wrote:
On Fri, 13 Jul 2018 20:53:33 -0500, AMuzi wrote:
On 7/13/2018 8:14 PM, Ralph Barone wrote:
John B. Slocomb wrote:
On Fri, 13 Jul 2018 12:49:33 +0000 (UTC), Ralph Barone wrote:
John B. Slocomb wrote:


A bottom bracket is usually specified as 7 - 8 mm thick.


Maybe 3-4 mm. Are you quoting the difference between the
OD and ID, or the wall thickness?

I just looked at their catalog which red, for example:
"LB100R - For 22.2mm Chainstays. 60.30x62.30x7\ufffd.
No guides or cut-outs".
or
"LB109R - With Oval 30x17mm. Chainstays.
Angles 60x64x7.30\ufffd. No guides or cut-outs."

Given that the first two numbers were obviously length and
breadth assumed the last was thickness. Not so?


I don't know. I just thought that 7mm wall thickness for a
bottom bracket shell appeared to be overkill to me. I did
some web searching and nobody publishes data on the OD of
bottom bracket shells (probably because it doesn't matter to
a first approximation). However, looking through a bunch of
diagrams, I did see that many of them had a 7mm deep pocket
to hold the bearings. Perhaps that's where your 7 came from.

Aha! This BB shell has a 38 mm OD and a 1.370" ID, which
gives about 2mm wall thickness.
https://framebuildersupply.com/produ...od-made-in-usa


Say that again, slowly. The O.D. is 38mm and th I.D. is 1.370??


The I.D. is given in inches, so the two dimensions definitely look
odd together.

:-) I believe tat the first demension is more then likely to be a thread demension :-)


That would be 38mm overall, 34.8mm at thread peaks or ~33.8 at
thread root leaving about 4+mm dia or 2+mm at the radius
theoretically. Which comports roughly with actual measurements
yesterday. Surely not 7mm on any modern (not cast iron)
threaded BB shell.


I suppose it's possible that tandem bottom bracket shells can be
thinner walled because the eccentric provides some strength, but
somehow I doubt they actually are.

At any rate, I just measured (roughly) the wall thickness of my
two tandem BB shells and the 1986 Rodriguez (aluminum) is about 4
mm, and the 2012 Santana (titanium) is somewhat less--maybe 3.5
mm.

Relating to the original topic, neither has any holes drilled in
the seat stays or the chain stays. The Santana has some kind of
reinforcement (maybe like the Rivnuts that have been discussed?)
at the water bottle cage holes in the frame tubes (down tube and
both laterals).


Not much detail for the frame except that they are made from Columbus
Spirit-Niobium 6/3/6 tubing which is high end, low weight, tubing. I
would guess that the frame holes were probably reinforced with
something like http://www.framebuilding.com/Bosses.htm, ART.472 with
maybe an additional ART.361 or 367.

Certainly not a revnut in that type of frame :-)

A useful reference is http://www.framebuilding.com/ as it shows a
great many of the usual frame making bits and pieces.
  #124  
Old July 15th 18, 03:20 AM posted to rec.bicycles.tech
David Scheidt
external usenet poster
 
Posts: 1,241
Default drill/tap in frames

AMuzi wrote:
:On 7/12/2018 10:59 AM, Frank Krygowski wrote:
: On 7/12/2018 11:39 AM, Jeff Liebermann wrote:
: On Thu, 12 Jul 2018 00:22:57 -0700, John B. Slocomb
:
: wrote:
:
: On Wed, 11 Jul 2018 20:16:33 -0700, Jeff Liebermann
:
: wrote:
: 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.
:
: I'd think it obvious that any hole drilled laterally into
: a tube would
: have an effect on the bending strength of the tube. The
: question
: wouldn't be whether the rivnut changed the strength of
: the tube but
: whether the tube was strong enough with the rivnut
: installed in the
: tube.
:
: Again, I expect some reinforcing effect from the Rivnut's
: clamping action. For an analogy: Did steel frames fail in
: significant numbers when water bottle bosses were brazed on
: and tapped? I doubt it. While a crimped-on Rivnut wouldn't
: add as much strength (as a guess) I think it may add enough
: to get the strength back up to that of the un-drilled tube.
:
: Also, I'm pretty sure a bike down tube sees little if any
: bending stress, except perhaps in a crash. The stresses of
: concern are torsional.
:
:
: Agreed.
:
: Reading between the lines, what others are apparently
: suggesting is
: that even with a hole drilled into the frame, the tubing
: is still
: sufficiently strong to consider the bicycle rideable. In
: other words,
: if the drilling a hole and installing a Rivnut decreased
: the bending
: strength by 10%, I would agree that the hole and Rivnut
: don't pose a
: risk. However, if it decreased the strength by 50%, I
: would consider
: it a hazardous modification. I'm not too sure what to do
: about
: numbers in between or even if the 10% is realistic.
:
: To complicate matters, there's the problem of the notch
: required by
: Rivnuts to prevent rotation. That's a stress riser by
: anyone's
: definition and will probably be the start of any break
: during testing.
: I'll try to position it where it will do the least damage.
:
: The notch is small enough to be enveloped in the crimped
: portion of the Rivnut. I doubt that it's effective as a
: stress riser. Really, I doubt that it feels any significant
: stress, other than compression from the clamping or crimping
: action.
:

:In practice, crashed frame tubes don't deform at the bottle
:bosses. The general truism is that a brazed joint is as
:strong or stronger than the steel tube so a brazed insert
oses no risk. That may not be exactly correct but we work
:with it.

:Some builders at the cusp of change between 'no brazed bits'
:and 'braze every possible thing' fashions (like Galmozzi)
:brazed bolts on the tube and so nuts secured the bottle
:cage. Odd looking but worked as well as anything.

I got a nasty gash from a frame like that. Just picked it up, and cut
myself on the bolt.



--
sig 126
  #125  
Old July 15th 18, 04:06 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 5,959
Default drill/tap in frames

On 7/14/2018 10:20 PM, David Scheidt wrote:
AMuzi wrote:
:On 7/12/2018 10:59 AM, Frank Krygowski wrote:
: On 7/12/2018 11:39 AM, Jeff Liebermann wrote:
: On Thu, 12 Jul 2018 00:22:57 -0700, John B. Slocomb
:
: wrote:
:
: On Wed, 11 Jul 2018 20:16:33 -0700, Jeff Liebermann
:
: wrote:
: 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.
:
: I'd think it obvious that any hole drilled laterally into
: a tube would
: have an effect on the bending strength of the tube. The
: question
: wouldn't be whether the rivnut changed the strength of
: the tube but
: whether the tube was strong enough with the rivnut
: installed in the
: tube.
:
: Again, I expect some reinforcing effect from the Rivnut's
: clamping action. For an analogy: Did steel frames fail in
: significant numbers when water bottle bosses were brazed on
: and tapped? I doubt it. While a crimped-on Rivnut wouldn't
: add as much strength (as a guess) I think it may add enough
: to get the strength back up to that of the un-drilled tube.
:
: Also, I'm pretty sure a bike down tube sees little if any
: bending stress, except perhaps in a crash. The stresses of
: concern are torsional.
:
:
: Agreed.
:
: Reading between the lines, what others are apparently
: suggesting is
: that even with a hole drilled into the frame, the tubing
: is still
: sufficiently strong to consider the bicycle rideable. In
: other words,
: if the drilling a hole and installing a Rivnut decreased
: the bending
: strength by 10%, I would agree that the hole and Rivnut
: don't pose a
: risk. However, if it decreased the strength by 50%, I
: would consider
: it a hazardous modification. I'm not too sure what to do
: about
: numbers in between or even if the 10% is realistic.
:
: To complicate matters, there's the problem of the notch
: required by
: Rivnuts to prevent rotation. That's a stress riser by
: anyone's
: definition and will probably be the start of any break
: during testing.
: I'll try to position it where it will do the least damage.
:
: The notch is small enough to be enveloped in the crimped
: portion of the Rivnut. I doubt that it's effective as a
: stress riser. Really, I doubt that it feels any significant
: stress, other than compression from the clamping or crimping
: action.
:

:In practice, crashed frame tubes don't deform at the bottle
:bosses. The general truism is that a brazed joint is as
:strong or stronger than the steel tube so a brazed insert
oses no risk. That may not be exactly correct but we work
:with it.

:Some builders at the cusp of change between 'no brazed bits'
:and 'braze every possible thing' fashions (like Galmozzi)
:brazed bolts on the tube and so nuts secured the bottle
:cage. Odd looking but worked as well as anything.

I got a nasty gash from a frame like that. Just picked it up, and cut
myself on the bolt.


Yet another bicycling injury!

--
- Frank Krygowski
  #126  
Old July 15th 18, 04:50 PM posted to rec.bicycles.tech
John B. Slocomb
external usenet poster
 
Posts: 7
Default drill/tap in frames

On Sun, 15 Jul 2018 11:06:37 -0400, Frank Krygowski
wrote:

On 7/14/2018 10:20 PM, David Scheidt wrote:
AMuzi wrote:
:On 7/12/2018 10:59 AM, Frank Krygowski wrote:
: On 7/12/2018 11:39 AM, Jeff Liebermann wrote:
: On Thu, 12 Jul 2018 00:22:57 -0700, John B. Slocomb
:
: wrote:
:
: On Wed, 11 Jul 2018 20:16:33 -0700, Jeff Liebermann
:
: wrote:
: 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.
:
: I'd think it obvious that any hole drilled laterally into
: a tube would
: have an effect on the bending strength of the tube. The
: question
: wouldn't be whether the rivnut changed the strength of
: the tube but
: whether the tube was strong enough with the rivnut
: installed in the
: tube.
:
: Again, I expect some reinforcing effect from the Rivnut's
: clamping action. For an analogy: Did steel frames fail in
: significant numbers when water bottle bosses were brazed on
: and tapped? I doubt it. While a crimped-on Rivnut wouldn't
: add as much strength (as a guess) I think it may add enough
: to get the strength back up to that of the un-drilled tube.
:
: Also, I'm pretty sure a bike down tube sees little if any
: bending stress, except perhaps in a crash. The stresses of
: concern are torsional.
:
:
: Agreed.
:
: Reading between the lines, what others are apparently
: suggesting is
: that even with a hole drilled into the frame, the tubing
: is still
: sufficiently strong to consider the bicycle rideable. In
: other words,
: if the drilling a hole and installing a Rivnut decreased
: the bending
: strength by 10%, I would agree that the hole and Rivnut
: don't pose a
: risk. However, if it decreased the strength by 50%, I
: would consider
: it a hazardous modification. I'm not too sure what to do
: about
: numbers in between or even if the 10% is realistic.
:
: To complicate matters, there's the problem of the notch
: required by
: Rivnuts to prevent rotation. That's a stress riser by
: anyone's
: definition and will probably be the start of any break
: during testing.
: I'll try to position it where it will do the least damage.
:
: The notch is small enough to be enveloped in the crimped
: portion of the Rivnut. I doubt that it's effective as a
: stress riser. Really, I doubt that it feels any significant
: stress, other than compression from the clamping or crimping
: action.
:

:In practice, crashed frame tubes don't deform at the bottle
:bosses. The general truism is that a brazed joint is as
:strong or stronger than the steel tube so a brazed insert
oses no risk. That may not be exactly correct but we work
:with it.

:Some builders at the cusp of change between 'no brazed bits'
:and 'braze every possible thing' fashions (like Galmozzi)
:brazed bolts on the tube and so nuts secured the bottle
:cage. Odd looking but worked as well as anything.

I got a nasty gash from a frame like that. Just picked it up, and cut
myself on the bolt.


Yet another bicycling injury!


Obviously not wearing a helmet.
  #127  
Old July 15th 18, 08:46 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 5,959
Default drill/tap in frames

On 7/15/2018 11:50 AM, John B. Slocomb wrote:
On Sun, 15 Jul 2018 11:06:37 -0400, Frank Krygowski
wrote:

On 7/14/2018 10:20 PM, David Scheidt wrote:
AMuzi wrote:
:On 7/12/2018 10:59 AM, Frank Krygowski wrote:
: On 7/12/2018 11:39 AM, Jeff Liebermann wrote:
: On Thu, 12 Jul 2018 00:22:57 -0700, John B. Slocomb
:
: wrote:
:
: On Wed, 11 Jul 2018 20:16:33 -0700, Jeff Liebermann
:
: wrote:
: 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.
:
: I'd think it obvious that any hole drilled laterally into
: a tube would
: have an effect on the bending strength of the tube. The
: question
: wouldn't be whether the rivnut changed the strength of
: the tube but
: whether the tube was strong enough with the rivnut
: installed in the
: tube.
:
: Again, I expect some reinforcing effect from the Rivnut's
: clamping action. For an analogy: Did steel frames fail in
: significant numbers when water bottle bosses were brazed on
: and tapped? I doubt it. While a crimped-on Rivnut wouldn't
: add as much strength (as a guess) I think it may add enough
: to get the strength back up to that of the un-drilled tube.
:
: Also, I'm pretty sure a bike down tube sees little if any
: bending stress, except perhaps in a crash. The stresses of
: concern are torsional.
:
:
: Agreed.
:
: Reading between the lines, what others are apparently
: suggesting is
: that even with a hole drilled into the frame, the tubing
: is still
: sufficiently strong to consider the bicycle rideable. In
: other words,
: if the drilling a hole and installing a Rivnut decreased
: the bending
: strength by 10%, I would agree that the hole and Rivnut
: don't pose a
: risk. However, if it decreased the strength by 50%, I
: would consider
: it a hazardous modification. I'm not too sure what to do
: about
: numbers in between or even if the 10% is realistic.
:
: To complicate matters, there's the problem of the notch
: required by
: Rivnuts to prevent rotation. That's a stress riser by
: anyone's
: definition and will probably be the start of any break
: during testing.
: I'll try to position it where it will do the least damage.
:
: The notch is small enough to be enveloped in the crimped
: portion of the Rivnut. I doubt that it's effective as a
: stress riser. Really, I doubt that it feels any significant
: stress, other than compression from the clamping or crimping
: action.
:

:In practice, crashed frame tubes don't deform at the bottle
:bosses. The general truism is that a brazed joint is as
:strong or stronger than the steel tube so a brazed insert
oses no risk. That may not be exactly correct but we work
:with it.

:Some builders at the cusp of change between 'no brazed bits'
:and 'braze every possible thing' fashions (like Galmozzi)
:brazed bolts on the tube and so nuts secured the bottle
:cage. Odd looking but worked as well as anything.

I got a nasty gash from a frame like that. Just picked it up, and cut
myself on the bolt.


Yet another bicycling injury!


Obviously not wearing a helmet.


I saw a head injury yesterday. After eating lunch on a backyard deck, a
good friend pushed his chair back from the table and tumbled backwards
off the deck. He hit the back of his head pretty hard on the brick
walkway, hard enough that he applied an ice pack for 15 minutes.

He's not a cyclist. Still, too bad he hadn't worn a helmet. If he had,
it _obviously_ would have saved his life.


--
- Frank Krygowski
  #128  
Old July 15th 18, 09:19 PM posted to rec.bicycles.tech
Theodore Heise[_2_]
external usenet poster
 
Posts: 55
Default drill/tap in frames

On Sat, 14 Jul 2018 18:48:20 -0700,
john B john wrote:
On Sat, 14 Jul 2018 15:52:39 +0000 (UTC), Theodore Heise
wrote:
On Sat, 14 Jul 2018 08:23:09 -0500,
AMuzi wrote:
On 7/14/2018 2:01 AM, John B Slocomb wrote:
On Fri, 13 Jul 2018 20:53:33 -0500, AMuzi wrote:
On 7/13/2018 8:14 PM, Ralph Barone wrote:
John B. Slocomb wrote:
On Fri, 13 Jul 2018 12:49:33 +0000 (UTC), Ralph Barone wrote:
John B. Slocomb wrote:


A bottom bracket is usually specified as 7 - 8 mm
thick.


Maybe 3-4 mm. Are you quoting the difference between
the OD and ID, or the wall thickness?

I just looked at their catalog which red, for example:
"LB100R - For 22.2mm Chainstays. 60.30x62.30x7\ufffd. No
guides or cut-outs". or "LB109R - With Oval 30x17mm.
Chainstays. Angles 60x64x7.30\ufffd. No guides or
cut-outs."

Given that the first two numbers were obviously length
and breadth assumed the last was thickness. Not so?


I don't know. I just thought that 7mm wall thickness for
a bottom bracket shell appeared to be overkill to me. I
did some web searching and nobody publishes data on the
OD of bottom bracket shells (probably because it doesn't
matter to a first approximation). However, looking
through a bunch of diagrams, I did see that many of them
had a 7mm deep pocket to hold the bearings. Perhaps
that's where your 7 came from.

Aha! This BB shell has a 38 mm OD and a 1.370" ID, which
gives about 2mm wall thickness.
https://framebuildersupply.com/produ...od-made-in-usa

Say that again, slowly. The O.D. is 38mm and th I.D. is
1.370??


The I.D. is given in inches, so the two dimensions definitely
look odd together.

:-) I believe tat the first demension is more then likely to be
a thread demension :-)

That would be 38mm overall, 34.8mm at thread peaks or ~33.8
at thread root leaving about 4+mm dia or 2+mm at the radius
theoretically. Which comports roughly with actual
measurements yesterday. Surely not 7mm on any modern (not
cast iron) threaded BB shell.


I suppose it's possible that tandem bottom bracket shells can
be thinner walled because the eccentric provides some strength,
but somehow I doubt they actually are.

At any rate, I just measured (roughly) the wall thickness of my
two tandem BB shells and the 1986 Rodriguez (aluminum) is about
4 mm, and the 2012 Santana (titanium) is somewhat less--maybe
3.5 mm.

Relating to the original topic, neither has any holes drilled
in the seat stays or the chain stays. The Santana has some
kind of reinforcement (maybe like the Rivnuts that have been
discussed?) at the water bottle cage holes in the frame tubes
(down tube and both laterals).


Not much detail for the frame except that they are made from
Columbus Spirit-Niobium 6/3/6 tubing which is high end, low
weight, tubing.


Um, no. I did mention (in the previous paragraph) that it is a
titanium frame.

... I would guess that the frame holes were probably reinforced
with something like http://www.framebuilding.com/Bosses.htm,
ART.472 with maybe an additional ART.361 or 367.


The ART 475 (Thin Head) looks like what's on the bike.


Certainly not a revnut in that type of frame :-)


I'm not surprised, I was just guessing--hence, the question mark.

--
Ted Heise West Lafayette, IN, USA
  #129  
Old July 15th 18, 11:42 PM posted to rec.bicycles.tech
John B. Slocomb
external usenet poster
 
Posts: 7
Default drill/tap in frames

On Sun, 15 Jul 2018 20:19:21 +0000 (UTC), Theodore Heise
wrote:

On Sat, 14 Jul 2018 18:48:20 -0700,
john B john wrote:
On Sat, 14 Jul 2018 15:52:39 +0000 (UTC), Theodore Heise
wrote:
On Sat, 14 Jul 2018 08:23:09 -0500,
AMuzi wrote:
On 7/14/2018 2:01 AM, John B Slocomb wrote:
On Fri, 13 Jul 2018 20:53:33 -0500, AMuzi wrote:
On 7/13/2018 8:14 PM, Ralph Barone wrote:
John B. Slocomb wrote:
On Fri, 13 Jul 2018 12:49:33 +0000 (UTC), Ralph Barone wrote:
John B. Slocomb wrote:

A bottom bracket is usually specified as 7 - 8 mm
thick.

Maybe 3-4 mm. Are you quoting the difference between
the OD and ID, or the wall thickness?

I just looked at their catalog which red, for example:
"LB100R - For 22.2mm Chainstays. 60.30x62.30x7\ufffd. No
guides or cut-outs". or "LB109R - With Oval 30x17mm.
Chainstays. Angles 60x64x7.30\ufffd. No guides or
cut-outs."

Given that the first two numbers were obviously length
and breadth assumed the last was thickness. Not so?

I don't know. I just thought that 7mm wall thickness for
a bottom bracket shell appeared to be overkill to me. I
did some web searching and nobody publishes data on the
OD of bottom bracket shells (probably because it doesn't
matter to a first approximation). However, looking
through a bunch of diagrams, I did see that many of them
had a 7mm deep pocket to hold the bearings. Perhaps
that's where your 7 came from.

Aha! This BB shell has a 38 mm OD and a 1.370" ID, which
gives about 2mm wall thickness.
https://framebuildersupply.com/produ...od-made-in-usa

Say that again, slowly. The O.D. is 38mm and th I.D. is
1.370??

The I.D. is given in inches, so the two dimensions definitely
look odd together.

:-) I believe tat the first demension is more then likely to be
a thread demension :-)

That would be 38mm overall, 34.8mm at thread peaks or ~33.8
at thread root leaving about 4+mm dia or 2+mm at the radius
theoretically. Which comports roughly with actual
measurements yesterday. Surely not 7mm on any modern (not
cast iron) threaded BB shell.

I suppose it's possible that tandem bottom bracket shells can
be thinner walled because the eccentric provides some strength,
but somehow I doubt they actually are.

At any rate, I just measured (roughly) the wall thickness of my
two tandem BB shells and the 1986 Rodriguez (aluminum) is about
4 mm, and the 2012 Santana (titanium) is somewhat less--maybe
3.5 mm.

Relating to the original topic, neither has any holes drilled
in the seat stays or the chain stays. The Santana has some
kind of reinforcement (maybe like the Rivnuts that have been
discussed?) at the water bottle cage holes in the frame tubes
(down tube and both laterals).


Not much detail for the frame except that they are made from
Columbus Spirit-Niobium 6/3/6 tubing which is high end, low
weight, tubing.


Um, no. I did mention (in the previous paragraph) that it is a
titanium frame.

Then it obviously isn't a "Columbus Spirit-Niobium" frame :-)

... I would guess that the frame holes were probably reinforced
with something like http://www.framebuilding.com/Bosses.htm,
ART.472 with maybe an additional ART.361 or 367.


The ART 475 (Thin Head) looks like what's on the bike.


Certainly not a revnut in that type of frame :-)


I'm not surprised, I was just guessing--hence, the question mark.

 




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