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  #31  
Old March 10th 18, 01:06 AM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 5,697
Default US steel trade war

On Fri, 09 Mar 2018 15:32:23 +0100, Emanuel Berg
wrote:

AMuzi wrote:

What do you have handy? A milling machine is
fast if you're making a lot of miters but
a file works just fine for one


I have a big stationary vertical drill if that
is what you mean by "milling machine", so then
it is just a matter of getting the round
saw/drill thing (?) and some sort of
arrangement to fixate the tube?


To answer your question. No a drill press is not a vertical milling
machine :-(

But yes, you could use a drill press with a hole saw to miter the end
of a tube. Alignment might present a problem but can be overcome.

On the other hand if you know how to file it might even be quicker,
for one tube end, to simply mark the tube and file to shape.

There is a very old application called "Tubemiter.exe" that has been
around for years and years that given tube diameters and joining angle
will print out a template that you can wrap around a tube to mark the
actual cut.

--
Cheers,

John B.

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  #32  
Old March 10th 18, 01:17 AM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 5,697
Default US steel trade war

On Fri, 9 Mar 2018 14:54:00 -0500, Frank Krygowski
wrote:

On 3/9/2018 8:52 AM, AMuzi wrote:
On 3/9/2018 12:54 AM, Emanuel Berg wrote:
AMuzi wrote:

Aluminum is no good for a bike frame because
it's too harsh and stiff. Aluminum won't work
either because it's too soft and noodly.
That went on just forever with, as always,
much digression.

One on-topic question on aluminium/aluminum
I thought about asking is how do they cut the
pipes so to get those roundish forms so that
for example the top and down tube aligns so
well with the head tube?


What do you have handy?
A milling machine is fast if you're making a lot of miters but a file
works just fine for one:

http://www.yellowjersey.org/photosfromthepast/MAK8B.JPG


IIRC, Cannondale pioneered using CNC to cut the miters with added tabs,
slots, etc. to allow more precise alignment prior to welding. That
doesn't matter for Emanuel's projects, though.

Maybe someday he'll want to splurge on a full set of frame building
fixtures like these:

http://www.henryjames.com/bicyle-par...equipment.html

http://www.alexmeade.com/Tools.htm

BTW, lots of people call those "jigs" but industrial tool designers
would call them "fixtures." The word "jig" is supposed to apply to
things that physically guide the cutting tool, not just hold parts in
position.

OK, that's enough pedantry for today.



Actually some of the old guys that used to build classic bikes used a
lot simpler fixtures then those sold by Henry James (cheaper too). I
remember a youtube about some old Japanese builder of classic steel
bikes who seemed to have a fixture for holding the seat tube and
bottom bracket at 90 degrees for brazing and then aligning everything
else with hand tools to the BB/Seat Tube assembly.

Although admittedly the Henry James "hold everything" fixture is
probably faster if you are churning out quantities of frames.
--
Cheers,

John B.

  #33  
Old March 10th 18, 09:13 AM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
Default US steel trade war

John B. wrote:

Although admittedly the Henry James "hold
everything" fixture is probably faster if you
are churning out quantities of frames.


What workstandish tools and stays should you
get to hold tubes? I have all the everyday
carpentry clamps and so on, of course, but they
hardly give that kind of confidence.

--
underground experts united
http://user.it.uu.se/~embe8573
  #34  
Old March 10th 18, 10:32 AM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 5,697
Default US steel trade war

On Sat, 10 Mar 2018 09:13:23 +0100, Emanuel Berg
wrote:

John B. wrote:

Although admittedly the Henry James "hold
everything" fixture is probably faster if you
are churning out quantities of frames.


What workstandish tools and stays should you
get to hold tubes? I have all the everyday
carpentry clamps and so on, of course, but they
hardly give that kind of confidence.


If you are talking about a frame building fixture then see:
https://tinyurl.com/ycns6zu2

--
Cheers,

John B.

  #35  
Old March 10th 18, 10:37 AM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
Default US steel trade war

John B. wrote:

If you are talking about a frame building
fixture then see:
https://tinyurl.com/ycns6zu2


I'm talking about holding tubes/pipes in
general but yes I suppose holding a bike frame,
even an incomplete frame, is the same thing,
only even more difficult with more complex
balance issues, protruding parts...

--
underground experts united
http://user.it.uu.se/~embe8573
  #36  
Old March 10th 18, 12:45 PM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default US steel trade war

On Sat, 10 Mar 2018 10:37:50 +0100, Emanuel Berg
wrote:

John B. wrote:

If you are talking about a frame building
fixture then see:
https://tinyurl.com/ycns6zu2


I'm talking about holding tubes/pipes in
general but yes I suppose holding a bike frame,
even an incomplete frame, is the same thing,
only even more difficult with more complex
balance issues, protruding parts...


If you are talking about holding a single tube, say while you file a
miter on the end then most shops will use something like:
http://steintoolsforbikes.com/produc...olding-blocks/

Often made from two blocks of hard wood for bench work but usually
machined from metal is used in a machine.
--
Cheers,

John B.

  #37  
Old March 10th 18, 05:06 PM posted to rec.bicycles.tech
Tim McNamara
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Posts: 6,945
Default US steel trade war

On Sat, 10 Mar 2018 07:17:58 +0700, John B wrote:

Actually some of the old guys that used to build classic bikes used a
lot simpler fixtures then those sold by Henry James (cheaper too). I
remember a youtube about some old Japanese builder of classic steel
bikes who seemed to have a fixture for holding the seat tube and
bottom bracket at 90 degrees for brazing and then aligning everything
else with hand tools to the BB/Seat Tube assembly.


When I built my frame in the shop of a friend, his technique was to
start with that connection and to have it plumb and square to the faces
of the BB, which he considered the reference point for the frame. Every
other tube was added without rigid fixtures, using a flat table and
supports. Then each new tube was aligned relative to the faces of the
BB. His goal was to build a frame with no residual internal stresses,
so that if you were to saw through the top tube the ends would remain
aligned.

"Why" is something I didn't quite understand, except that when the last
joint was done the frame was almost perfectly aligned and required only
a few tweaks at the dropouts. The frame I built has held up for over a
decade now, but let's face it most frames hold up for many decades
unless they are damaged.

Although admittedly the Henry James "hold everything" fixture is
probably faster if you are churning out quantities of frames.


Yep. His complaint about this was that clamping the frame into a rigid
fixure and then brazing away resulted in a frame with internal stresses
that were not relieved. After finishing the brazing or welding the
frame usually has to be forcibly aligned. My friend thought that was a
bad thing. I am not sure it makes any difference in terms of longevity
and seems very unlikely to make any difference in the performance of the
frame.

OTOH, the best frame builder around here had a Henry James fixture and
the bike he built for me is the best riding one I have ever been on (or
was until I mangled it in my cash last summer. Have a replacement on
order).
  #38  
Old March 11th 18, 03:04 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default US steel trade war

On Sat, 10 Mar 2018 10:06:11 -0600, Tim McNamara
wrote:

On Sat, 10 Mar 2018 07:17:58 +0700, John B wrote:

Actually some of the old guys that used to build classic bikes used a
lot simpler fixtures then those sold by Henry James (cheaper too). I
remember a youtube about some old Japanese builder of classic steel
bikes who seemed to have a fixture for holding the seat tube and
bottom bracket at 90 degrees for brazing and then aligning everything
else with hand tools to the BB/Seat Tube assembly.


When I built my frame in the shop of a friend, his technique was to
start with that connection and to have it plumb and square to the faces
of the BB, which he considered the reference point for the frame. Every
other tube was added without rigid fixtures, using a flat table and
supports. Then each new tube was aligned relative to the faces of the
BB. His goal was to build a frame with no residual internal stresses,
so that if you were to saw through the top tube the ends would remain
aligned.

"Why" is something I didn't quite understand, except that when the last
joint was done the frame was almost perfectly aligned and required only
a few tweaks at the dropouts. The frame I built has held up for over a
decade now, but let's face it most frames hold up for many decades
unless they are damaged.


I think that using the Bottom Bracket as the basic reference point is
the common way of building a frame.

Although admittedly the Henry James "hold everything" fixture is
probably faster if you are churning out quantities of frames.


Yep. His complaint about this was that clamping the frame into a rigid
fixure and then brazing away resulted in a frame with internal stresses
that were not relieved. After finishing the brazing or welding the
frame usually has to be forcibly aligned. My friend thought that was a
bad thing. I am not sure it makes any difference in terms of longevity
and seems very unlikely to make any difference in the performance of the
frame


Given that the fork blades often are sold as a straight tube and the
frame maker then bends them to the proper radius to achieve the
desired trail obviously the act of simply bending a frame tube can't
be as evil as it sounds :-)



OTOH, the best frame builder around here had a Henry James fixture and
the bike he built for me is the best riding one I have ever been on (or
was until I mangled it in my cash last summer. Have a replacement on
order).

--
Cheers,

John B.

  #39  
Old March 11th 18, 05:05 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 13,447
Default US steel trade war

On 3/10/2018 8:04 PM, John B. wrote:
On Sat, 10 Mar 2018 10:06:11 -0600, Tim McNamara
wrote:

On Sat, 10 Mar 2018 07:17:58 +0700, John B wrote:

Actually some of the old guys that used to build classic bikes used a
lot simpler fixtures then those sold by Henry James (cheaper too). I
remember a youtube about some old Japanese builder of classic steel
bikes who seemed to have a fixture for holding the seat tube and
bottom bracket at 90 degrees for brazing and then aligning everything
else with hand tools to the BB/Seat Tube assembly.


When I built my frame in the shop of a friend, his technique was to
start with that connection and to have it plumb and square to the faces
of the BB, which he considered the reference point for the frame. Every
other tube was added without rigid fixtures, using a flat table and
supports. Then each new tube was aligned relative to the faces of the
BB. His goal was to build a frame with no residual internal stresses,
so that if you were to saw through the top tube the ends would remain
aligned.

"Why" is something I didn't quite understand, except that when the last
joint was done the frame was almost perfectly aligned and required only
a few tweaks at the dropouts. The frame I built has held up for over a
decade now, but let's face it most frames hold up for many decades
unless they are damaged.


I think that using the Bottom Bracket as the basic reference point is
the common way of building a frame.

Although admittedly the Henry James "hold everything" fixture is
probably faster if you are churning out quantities of frames.


Yep. His complaint about this was that clamping the frame into a rigid
fixure and then brazing away resulted in a frame with internal stresses
that were not relieved. After finishing the brazing or welding the
frame usually has to be forcibly aligned. My friend thought that was a
bad thing. I am not sure it makes any difference in terms of longevity
and seems very unlikely to make any difference in the performance of the
frame


Given that the fork blades often are sold as a straight tube and the
frame maker then bends them to the proper radius to achieve the
desired trail obviously the act of simply bending a frame tube can't
be as evil as it sounds :-)



OTOH, the best frame builder around here had a Henry James fixture and
the bike he built for me is the best riding one I have ever been on (or
was until I mangled it in my cash last summer. Have a replacement on
order).


" Given that the fork blades often are sold as a straight
tube and the
frame maker then bends them to the proper radius to

achieve the
desired trail obviously the act of simply bending a frame

tube can't
be as evil as it sounds :-)"



Right in principle but everything has limits.

Also there's a difference between some small structural loss
from crystal slip on a raked fork and internal stress plus
cyclic loading in a closed brazed or welded figure. Fork
failure at the curved portion of a blade is virtually
unknown yet tube failure from initial misalignment is sadly
regular. Not epidemic mind you but frequent enough to be a
known issue.

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


  #40  
Old March 12th 18, 03:30 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default US steel trade war

On Sun, 11 Mar 2018 11:05:18 -0500, AMuzi wrote:

On 3/10/2018 8:04 PM, John B. wrote:
On Sat, 10 Mar 2018 10:06:11 -0600, Tim McNamara
wrote:

On Sat, 10 Mar 2018 07:17:58 +0700, John B wrote:

Actually some of the old guys that used to build classic bikes used a
lot simpler fixtures then those sold by Henry James (cheaper too). I
remember a youtube about some old Japanese builder of classic steel
bikes who seemed to have a fixture for holding the seat tube and
bottom bracket at 90 degrees for brazing and then aligning everything
else with hand tools to the BB/Seat Tube assembly.

When I built my frame in the shop of a friend, his technique was to
start with that connection and to have it plumb and square to the faces
of the BB, which he considered the reference point for the frame. Every
other tube was added without rigid fixtures, using a flat table and
supports. Then each new tube was aligned relative to the faces of the
BB. His goal was to build a frame with no residual internal stresses,
so that if you were to saw through the top tube the ends would remain
aligned.

"Why" is something I didn't quite understand, except that when the last
joint was done the frame was almost perfectly aligned and required only
a few tweaks at the dropouts. The frame I built has held up for over a
decade now, but let's face it most frames hold up for many decades
unless they are damaged.


I think that using the Bottom Bracket as the basic reference point is
the common way of building a frame.

Although admittedly the Henry James "hold everything" fixture is
probably faster if you are churning out quantities of frames.

Yep. His complaint about this was that clamping the frame into a rigid
fixure and then brazing away resulted in a frame with internal stresses
that were not relieved. After finishing the brazing or welding the
frame usually has to be forcibly aligned. My friend thought that was a
bad thing. I am not sure it makes any difference in terms of longevity
and seems very unlikely to make any difference in the performance of the
frame


Given that the fork blades often are sold as a straight tube and the
frame maker then bends them to the proper radius to achieve the
desired trail obviously the act of simply bending a frame tube can't
be as evil as it sounds :-)



OTOH, the best frame builder around here had a Henry James fixture and
the bike he built for me is the best riding one I have ever been on (or
was until I mangled it in my cash last summer. Have a replacement on
order).


" Given that the fork blades often are sold as a straight
tube and the
frame maker then bends them to the proper radius to

achieve the
desired trail obviously the act of simply bending a frame

tube can't
be as evil as it sounds :-)"



Right in principle but everything has limits.

Also there's a difference between some small structural loss
from crystal slip on a raked fork and internal stress plus
cyclic loading in a closed brazed or welded figure. Fork
failure at the curved portion of a blade is virtually
unknown yet tube failure from initial misalignment is sadly
regular. Not epidemic mind you but frequent enough to be a
known issue.


You are talking about two very different thing. One, a permanently
deformed tube, and secondly a non-deformed tube that has been
deflected from its normal alignment and would return to the normal
alignment if freed from its attachments.

One of the problems is that simply welding or brazing two or more
pieces together will normally result in some distortion. Thus the cold
setting that many frames undergo before being *finished* :-)

--
Cheers,

John B.

 




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