More carbon fiber adventure

On 8/26/2012 4:25 PM, Lou Holtman wrote:
Op zondag 26 augustus 2012 16:42:37 UTC+2 schreef Frank Krygowski het volgende:
[...]
and the stuff is
a real pain to cut.
Nonsense, I drilled, filed and sanded TI with no trouble. It is very straight forward.

Titanium and it common alloys are much harder on tooling than normal
steels (for ultra high-strength steel, Chalo Colina can tell us about
working with Carpenter AerMet and the ilk).

--
Tºm Shermªn - 42.435731°N, 83.985007°W
Post Free or Die!

On Monday, August 27, 2012 12:42:37 AM UTC+10, Frank Krygowski wrote:
Lou Holtman wrote:

Op 26-8-2012 13:10, Peter Cole schreef:





Every material has its strengths and weaknesses. Metal corrodes,

fatigues, bends and dents. CF can delaminate from crushing and has poor

abrasion resistance. Steel and CF are, at least in theory, repairable.

Al and Ti, less so.



Ti is perfectly repairable and the only framematerial were it is

worthwile to do so IMO.



Titanium is "perfectly repairable?" I don't doubt it's possible, but

last I heard, special welding techniques were required, and the stuff is

a real pain to cut. My impression was that very few people are capable

of repairing titanium bike frames.


I would have thought a business that is in to building custom bike frames would have the ability to repair a bike frame made from the material(s) they specialise in - provided it is not damaged beyond repair.

--
JS

On Monday, August 27, 2012 8:30:20 AM UTC+10, Tom $herman (-_-) wrote:
On 8/26/2012 4:25 PM, Lou Holtman wrote:

Op zondag 26 augustus 2012 16:42:37 UTC+2 schreef Frank Krygowski het volgende:

[...]

and the stuff is

a real pain to cut.

Nonsense, I drilled, filed and sanded TI with no trouble. It is very straight forward.



Titanium and it common alloys are much harder on tooling than normal

steels (for ultra high-strength steel, Chalo Colina can tell us about

working with Carpenter AerMet and the ilk).


Are you saying "It can't be done."?

--
JS

On Monday, August 27, 2012 3:06:55 AM UTC+10, Tom $herman (-_-) wrote:
On 8/26/2012 6:43 AM, thirty-six wrote:



Aluminium is certainly repairable, it's just that the skills are

rare. There is now a special welding rod which makes the process

simpler, but essentially one needs to wire-brush under a flux to

remove the oxide. I've not seen titanium repaired..



But how do you do the post-weld heat treatment?


With a temperature controlled chamber? Just a guess. If the entire frame was heat treated once before, when it was first built, is it a problem to heat treat it again after a repair in the same fashion?

--
JS

On 8/26/2012 5:30 PM, Tom $herman (-_-) wrote:
On 8/26/2012 4:25 PM, Lou Holtman wrote:
Op zondag 26 augustus 2012 16:42:37 UTC+2 schreef Frank
Krygowski het volgende:
[...]
and the stuff is
a real pain to cut.
Nonsense, I drilled, filed and sanded TI with no trouble.
It is very straight forward.

Titanium and it common alloys are much harder on tooling
than normal steels (for ultra high-strength steel, Chalo
Colina can tell us about working with Carpenter AerMet and
the ilk).


Only because it's 'sticky' to turn, tap, drill or mill, like
brass only moreso. Titanium with hand saws, files or sanding
is no trouble at all and grinding operations are just
spectacular!

http://farm4.staticflickr.com/3089/3...15b_z.jpg?zz=1

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

On Aug 26, 11:41*pm, James wrote:
On Monday, August 27, 2012 3:06:55 AM UTC+10, Tom $herman (-_-) wrote:
On 8/26/2012 6:43 AM, thirty-six wrote:

Aluminium is certainly repairable, it's just that the skills are

rare. * There is now a special welding rod which makes the process

simpler, but essentially one needs to wire-brush under a flux to

remove the oxide. * I've not seen titanium repaired..

But how do you do the post-weld heat treatment?

With a temperature controlled chamber? *Just a guess. *If the entire frame was heat treated once before, when it was first built, is it a problem to heat treat it again after a repair in the same fashion?

--
JS

shove it in the oven and lose all the fancy graphics?

Lou wrote:
Op 26-8-2012 13:10, Peter Cole schreef:


Lou wrote:
Op 24-8-2012 15:49, thirty-six schreef:
On Aug 24, 4:26 am, Frank Krygowski
wrote:
I just got an email from a cycling friend who lives a couple hundred
miles from me, a guy who emails me fairly often. He says he was
riding
his new carbon fiber time trial bike on a familiar downhill bend. But
the brand new chip & seal surface near the bottom was not familiar at
all. The road surface had previously been asphalt, but surprise! Now
it's loosely packed gravel, at least until motor vehicle traffic
compacts it and kicks aside the excess.

He slid out and has some road rash. Apparently the crash wasn't very
bad, but his favorite bike mechanic at the shop where he bought the
bike, says the fork must be replaced, and perhaps the entire frame.

He said "This is my first carbon fiber bike, and they are so fragile!"

--
- Frank Krygowski

Seems odd to me. I've not managed to scratch a fork blade by simply
sliding out. I;ve taken off bar tape, ripped brake lever hoods and
sculpted brake levers, and I've managed to tear off a little tyre
tread and scrape a rim. Forks generally stay clear of the road unless
they've already snapped. I am well experienced in testing bicycle
lean angles, forks do not get scratched from a simple slide. May be
there is some other factor to this story such as failure to adequately
tighten front axle?

Or it is one of Franks bed time stories ;-)
Lou



Every material has its strengths and weaknesses. Metal corrodes,
fatigues, bends and dents. CF can delaminate from crushing and has poor
abrasion resistance. Steel and CF are, at least in theory, repairable.
Al and Ti, less so.
Ti is perfectly repairable and the only framematerial were it is
worthwile to do so IMO. The result is as good as new. What is the point
in trying to repair a cheap Al or steel frame were the result is not as
good as new. Sentimental value?

I have repaired a cheap steel frame with OA and brazing rod. The point was to keep riding it. Having worked with epoxy and read descriptions of home-built CF, I think I could repair CF, too.

Al & Ti can be TIG'ed of course, but finding Ti TIG welders and sophisticated Al welders might be a bit difficult and expensive. Not for me perhaps, Seven Cycles is right down the street.




I think it's good to understand the limits of materials when choosing
bike components.
Of course. That is my point in the first place. Frank picture just a one
sided view. That bugs me.
Lou

I think CF's susceptibility to abrasion is an important consideration. One can argue about how frequently it is encountered in the wild. There are many simple mishaps that can destroy a frame in any material. I don't think CF is particularly fragile, relatively speaking, and abrasion damage to frames seems fairly rare. I did see a carbon Look frame snap in a fairly minor spill a few years back, though. To be fair, any lightweight frame might have suffered the same fate.

--
Android Usenet Reader
http://android.newsgroupstats.hk

On 8/26/2012 5:45 PM, A. Muzi wrote:
On 8/26/2012 5:30 PM, Tom $herman (-_-) wrote:
On 8/26/2012 4:25 PM, Lou Holtman wrote:
Op zondag 26 augustus 2012 16:42:37 UTC+2 schreef Frank
Krygowski het volgende:
[...]
and the stuff is
a real pain to cut.
Nonsense, I drilled, filed and sanded TI with no trouble.
It is very straight forward.

Titanium and it common alloys are much harder on tooling
than normal steels (for ultra high-strength steel, Chalo
Colina can tell us about working with Carpenter AerMet and
the ilk).


Only because it's 'sticky' to turn, tap, drill or mill, like brass only
moreso. Titanium with hand saws, files or sanding is no trouble at all
and grinding operations are just spectacular!

http://farm4.staticflickr.com/3089/3...15b_z.jpg?zz=1

Hmmm, have a source for titanium acorn nuts?

Titanium is also hard to weld properly - I know of some semi-spectacular
failures of welds by people who did not have the proper combination of
equipment and skills.

--
Tºm Shermªn - 42.435731°N, 83.985007°W
Post Free or Die!

On 8/26/2012 6:31 PM, Tom $herman (-_-) wrote:
On 8/26/2012 5:45 PM, A. Muzi wrote:
On 8/26/2012 5:30 PM, Tom $herman (-_-) wrote:
On 8/26/2012 4:25 PM, Lou Holtman wrote:
Op zondag 26 augustus 2012 16:42:37 UTC+2 schreef Frank
Krygowski het volgende:
[...]
and the stuff is
a real pain to cut.
Nonsense, I drilled, filed and sanded TI with no trouble.
It is very straight forward.

Titanium and it common alloys are much harder on tooling
than normal steels (for ultra high-strength steel, Chalo
Colina can tell us about working with Carpenter AerMet and
the ilk).


Only because it's 'sticky' to turn, tap, drill or mill,
like brass only
moreso. Titanium with hand saws, files or sanding is no
trouble at all
and grinding operations are just spectacular!

http://farm4.staticflickr.com/3089/3...15b_z.jpg?zz=1


Hmmm, have a source for titanium acorn nuts?

Titanium is also hard to weld properly - I know of some
semi-spectacular failures of welds by people who did not
have the proper combination of equipment and skills.


Try looking for DIN1587 in titanium. A quick web search shows:
http://www.weiku.com/products/894719...nium_nuts.html

http://www.tradekr.com/cindex_48896_...nium-metal.htm

and many more similar results. If you need just a couple of
them, I have no idea.

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

I had some titanium and magnesium pieces repaired years ago. The welding and preparation process is much stricter for titanium, as the weld zone must be properly shielded from atmospheric oxygen during the weld as well as for much of the cooling process.

When joining tubing, I was impressed with the shield gas being fed to the inside of the tube as well, and the ingenious use of metal "trenches" to help keep the argon around the work area. With the Ti repair, I remember that all of the finishing tools were reserved for work with titanium only, to prevent any contamination.

Whether you are dealing with metals or composites, it all really boils down to the skill of the craftsman doing the work.