drill/tap in frames
 

On Fri, 13 Jul 2018 16:41:16 +0200, Emanuel Berg
wrote:

John B. Slocomb wrote:

And the mid-bottom part of the down tube?
The screws are interchangeable in size
and length.

Well that depends. Probably on the cost and
class of the bike. The down tube is pretty
thin on most better class road bikes.
Say Perhaps .6 - .7 mm in wall thickness.
Depending on whether it is butted, non
butted, etc,

These are not road bikes but ordinary standard
steel frames for commuting, shopping, and
everyday transport, say from the 80s.

Sorry but road bike data is all I have :-)

Yesterday BTW I saw a second bike with the
exact same configuration. The bracket is
bent so it is round along the tube surface,
but what holds it in its place seems to be
a single M5 screw with a flat PZ2 head.

Given that all the pedaling torque passes
through the bottom bracket I'd doubt if a new
bike would use a single screw to hold the BB
onto the frame tubes.

What is held are two stays that then hold
the chainguard.
--

Cheers,

John B.

drill/tap in frames
 

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?

--

Cheers,

John B.


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

drill/tap in frames
 

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


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.

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

drill/tap in frames
 

On 14/07/18 00:41, Emanuel Berg wrote:
John B. Slocomb wrote:

And the mid-bottom part of the down tube?
The screws are interchangeable in size
and length.

Well that depends. Probably on the cost and
class of the bike. The down tube is pretty
thin on most better class road bikes.
Say Perhaps .6 - .7 mm in wall thickness.
Depending on whether it is butted, non
butted, etc,

These are not road bikes but ordinary standard
steel frames for commuting, shopping, and
everyday transport, say from the 80s.


Regardless, the wall thickness of the main tubes will not be sufficient
to drill and tap sufficient threaded area to hold a bolt.

Yesterday BTW I saw a second bike with the
exact same configuration. The bracket is
bent so it is round along the tube surface,
but what holds it in its place seems to be
a single M5 screw with a flat PZ2 head.

Given that all the pedaling torque passes
through the bottom bracket I'd doubt if a new
bike would use a single screw to hold the BB
onto the frame tubes.

What is held are two stays that then hold
the chainguard.


Even the chain and seat stays are unlikely to be much more than 1mm
thick. If they were 1.5mm thick, that is still not enough thickness to
drill and tap a hole for a 5mm bolt.

Have a frame builder braze on a tab with a 6mm hole, and use a 5mm bolt
and nyloc nut.

Or to attach to a chain or seat stay, form a metal band around the tube
with a pair of 6mm holes at the ends, such that when the bolt and nut is
passed through and tightened and holding the chainguard, it also clamps
onto the tube. Use a rubber strip between the metal band and tube to
prevent paint damage and increase the clamp friction.

--
JS

drill/tap in frames
 

On 13/07/18 15:30, 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.

Not even close.

--
JS

drill/tap in frames
 

On Fri, 13 Jul 2018 12:49:32 +0000 (UTC), Ralph Barone
wrote:

John B. Slocomb wrote:
On Thu, 12 Jul 2018 23:19:23 -0400, Frank Krygowski
wrote:

On 7/12/2018 9:37 PM, AMuzi wrote:

One might argue that we make good hardware, software, armament and kit.
One might also argue that arms sales are more political than economic so
quality, price or performance may not even be factors when compared to
arm-bending 'deals one cannot refuse' as it were.

How political can arms sales possibly be?

https://sputniknews.com/us/201807081...ell-old-tanks/

Being Canadian, they wouldn't want their surplus tanks used to hurt
people or anything like that:

They should follow Bob Hope's lead. Few people know it, but Hope made a
killing buying and selling obsolete military equipment after WW2. He had
the connections due to his volunteer work, and he was able to get lots
of tanks, cannons, etc. for next to nothing.

He turned them around, selling them profitably to VFW halls, little
towns, etc. at prices that seemed great. They were bought for the war
memorials that still stand today.

And doing a good thing :-) In the 1945 period war surplus had almost
literally no value at all. If one could turn it into money it was
probably a patriotic act :-)

Hope even used his TV shows and stage performances to do subliminal
advertising. He was a pioneer at that. At every show, he promoted his
business by singing "Tanks for the memories." It worked.

--

Cheers,

John B.


John, I suspect Frank's post was a very long, subtle joke.
It might be. But in 1945 it probably wasn't :-)

drill/tap in frames
 

On Sat, 14 Jul 2018 13:24:12 +1000, James
wrote:

On 14/07/18 00:41, Emanuel Berg wrote:
John B. Slocomb wrote:

And the mid-bottom part of the down tube?
The screws are interchangeable in size
and length.

Well that depends. Probably on the cost and
class of the bike. The down tube is pretty
thin on most better class road bikes.
Say Perhaps .6 - .7 mm in wall thickness.
Depending on whether it is butted, non
butted, etc,

These are not road bikes but ordinary standard
steel frames for commuting, shopping, and
everyday transport, say from the 80s.


Regardless, the wall thickness of the main tubes will not be sufficient
to drill and tap sufficient threaded area to hold a bolt.

Of course not. After all one wants a slender and light bcycle so those
clever folks have made thraded inerts to solder to the frame where one
wants threads.

The idea of thicker sections whe it is wanted stronger is no new
idea.

Yesterday BTW I saw a second bike with the
exact same configuration. The bracket is
bent so it is round along the tube surface,
but what holds it in its place seems to be
a single M5 screw with a flat PZ2 head.

Given that all the pedaling torque passes
through the bottom bracket I'd doubt if a new
bike would use a single screw to hold the BB
onto the frame tubes.

What is held are two stays that then hold
the chainguard.


Even the chain and seat stays are unlikely to be much more than 1mm
thick. If they were 1.5mm thick, that is still not enough thickness to
drill and tap a hole for a 5mm bolt.

Have a frame builder braze on a tab with a 6mm hole, and use a 5mm bolt
and nyloc nut.

Or to attach to a chain or seat stay, form a metal band around the tube
with a pair of 6mm holes at the ends, such that when the bolt and nut is
passed through and tightened and holding the chainguard, it also clamps
onto the tube. Use a rubber strip between the metal band and tube to
prevent paint damage and increase the clamp friction.

drill/tap in frames
 

On Sat, 14 Jul 2018 01:14:20 +0000 (UTC), 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?

--

Cheers,

John B.


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.

I don't have a clue. The only thing I check on a new BB is that it has
the correct threads.

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

I finally went out to the shop and measures, as best I could, an
installed BB. It is in the neighborhood of 7 1- mm with some guessing
as the BB is installed and I'm guessing the measurements to some
extent.

Note that this is an old original threaded BB

drill/tap in frames
 

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.

drill/tap in frames
 

James wrote:

Regardless, the wall thickness of the main
tubes will not be sufficient to drill and tap
sufficient threaded area to hold a bolt.

I can only tell what I see with my own eyes.
And this is exactly what has happened, over and
over again, for these kind of bikes. So it is
possible. If it is possible for the Joe Sixpack
DIY-er, and if it is a good idea, are separate
questions tho.

--
underground experts united
http://user.it.uu.se/~embe8573