DIY carbon-fiber brackets?

"Gary Young" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

There are a few small parts I'd like to make for myself, including (1) a
bracket to hold one of Kryptonite's heavier u-locks, (2) a bracket mounted
to the front brake bolt to hold the front part of a fender and a generator
headlight, and (3) a bracket on saddle rails to allow quick release of a
Carradice-style saddlebag. For a lot of reasons, I don't find the
off-the-shelf brackets very satisfactory.

Ultimately, I'd like to learn how to braze, but for the time being it
seems as if carbon-fiber fabrication is much simpler for a beginner. Also,
since I have access to a heavy-duty vacuum pump, my initial costs would be
smaller. (I know that carbon fiber itself is expensive, but these are
fairly small parts.) I'm not concerned about ultra-lightness, so I don't
mind overbuilding the parts.

It's seems to me that I've seen carbon-fiber parts used in weight-bearing
applications (such as the bodies of Campy brake levers), but I'm no
engineer. I wouldn't want to go to a lot of trouble if the parts are
doomed to failure. Is this a sensible idea?

Sure you can do it. No reason you can't.
If I need to I can get small amounts of carbon fiber sheets and panels at
the local radio control hobby shop.
You can get the epoxy resins there too. Making a mold is pretty much wide
open as to materials and such.

I was going to build a bike out of MDF for a school design project, but a
friend convinced me to use fibreglas and CF. He told me about a local
windsurfer builder who would sell small quantited of cloth and resin, and I
ended up spending ~$200. I made a bike with 1 layer fiberglas and 1 layer
CF, 3 CF saddles (really easy!), part of a TT bar ( a few failed tries and I
abandoned it -went with Al) and 2 wheels (plywood with 1 layer CF). My bike
was a fully functional maquette with an Al skeleton, super-dense foam over
that, then the cloth. We had a bi enough oven at school for the frame ( I
forget the temp, but very low -not even neccessary to bake catalyzed resin,
but your parts sound like they'd fit in your home oven). It's not safe to
ride, but my point is that for not much money you can get enough materials
to make some bits, and some bits are very easy to make, the resin is easy to
mix, cloth is lovely to work with, and you stand a very good chance of
success, but I wouldn't do it this way for anything that could hurt you. It
was a lot of fun, and I really wish I had the space to keep doing it. Oh
well, at least I have my retirement planned!

"Gary Young" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

There are a few small parts I'd like to make for myself, including (1) a
bracket to hold one of Kryptonite's heavier u-locks, (2) a bracket mounted
to the front brake bolt to hold the front part of a fender and a generator
headlight, and (3) a bracket on saddle rails to allow quick release of a
Carradice-style saddlebag. For a lot of reasons, I don't find the
off-the-shelf brackets very satisfactory.

Ultimately, I'd like to learn how to braze, but for the time being it
seems as if carbon-fiber fabrication is much simpler for a beginner. Also,
since I have access to a heavy-duty vacuum pump, my initial costs would be
smaller. (I know that carbon fiber itself is expensive, but these are
fairly small parts.) I'm not concerned about ultra-lightness, so I don't
mind overbuilding the parts.

It's seems to me that I've seen carbon-fiber parts used in weight-bearing
applications (such as the bodies of Campy brake levers), but I'm no
engineer. I wouldn't want to go to a lot of trouble if the parts are
doomed to failure. Is this a sensible idea?

"David Rees" wrote: (clip) I made a bike with 1 layer fiberglas and 1 layer
CF, (clip)
^^^^^^^^^^^^^^^^^^^
You obviously have a handle on this. May I ask, what was the reason for
making the first layer out of fiberglas, and the second out of carbon?

Gary Young said:

There are a few small parts I'd like to make for myself, including (1) a
bracket to hold one of Kryptonite's heavier u-locks, (2) a bracket mounted
to the front brake bolt to hold the front part of a fender and a generator
headlight, and (3) a bracket on saddle rails to allow quick release of a
Carradice-style saddlebag. For a lot of reasons, I don't find the
off-the-shelf brackets very satisfactory.

Ultimately, I'd like to learn how to braze,

Having access to a welding setup can be entertaining. Many people seem
to gravitate to the wire welders but a torch has a few big advantages
when welding thin metals and isn't much more difficult to own. Just DO
NOT waste money buying the little disposable-tank setups; these don't
have different-sized tips and the gases sold in these low-pressure
disposable tanks end up being very expensive over the long run.

Quoted message said:

but for the time being it
seems as if carbon-fiber fabrication is much simpler for a beginner. Also,
since I have access to a heavy-duty vacuum pump, my initial costs would be
smaller. (I know that carbon fiber itself is expensive, but these are
fairly small parts.) I'm not concerned about ultra-lightness, so I don't
mind overbuilding the parts.

It's seems to me that I've seen carbon-fiber parts used in weight-bearing
applications (such as the bodies of Campy brake levers), but I'm no
engineer. I wouldn't want to go to a lot of trouble if the parts are
doomed to failure. Is this a sensible idea?

Composite construction does need a vacuum to do well, and you really
need a pressure-activated setup. Carbon fiber (and graphite) tends to
snap off clean; if you want a piece that will hold together even if it
cracks then you need to put some layers of Kevlar into it.

Also--be aware that some people (homebuilt boat and airplane
enthusiasts) have developed allergies to epoxy resins; usually this
seemed to be by skin contact with uncured resin but some have done it by
breathing fumes as well. Some of these stories are not pretty; the onset
can be severe and with many people, it prevents them from ever
practically working with the stuff again. If you work with resin you
must use a well-ventilated work area, respirators and the uncured
resin/hardener should NEVER touch your skin.

[-end-]

Cost! As a student, $200 was my limit, and one layer of glass and one CF
made for a nice crunchy shell (pretty crunch-proof with the underlying foam,
actually) and the fibreglas helped hide the pink foam, which would have
peeked through the CF weave wherever it separated, and as there are a good
number of compound curves, this would have been a major headache to retouch
with paint. Again, this was a non-rideable 1:1 functional model (steering
worked, etc) and the CF was for looks. The frameset alone is 19 lbs, and the
disc wheels, with a solid plywood core and solid steel hubs, I can't even
guess at. I wouldn't say I really have a handle on this, as I certainly
don't pretend to have the know-how to make a safe CF part like a frame,
fork, bars, seatpost, etc., but for bottle cages and such for personal use,
I'd be pretty confident. Lots of people have made their own sailboats, so I
guess if you can say "I won't die if this breaks", go for it!
"Leo Lichtman" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"David Rees" wrote: (clip) I made a bike with 1 layer fiberglas and 1
layer CF, (clip)
^^^^^^^^^^^^^^^^^^^
You obviously have a handle on this. May I ask, what was the reason for
making the first layer out of fiberglas, and the second out of carbon?

David Rees said:

Cost! As a student, $200 was my limit, and one layer of glass and one CF
made for a nice crunchy shell (pretty crunch-proof with the underlying foam,
actually) and the fibreglas helped hide the pink foam, which would have
peeked through the CF weave wherever it separated, and as there are a good
number of compound curves, this would have been a major headache to retouch
with paint. Again, this was a non-rideable 1:1 functional model (steering
worked, etc) and the CF was for looks. The frameset alone is 19 lbs, and the
disc wheels, with a solid plywood core and solid steel hubs, I can't even
guess at. I wouldn't say I really have a handle on this, as I certainly
don't pretend to have the know-how to make a safe CF part like a frame,
fork, bars, seatpost, etc., but for bottle cages and such for personal use,
I'd be pretty confident. Lots of people have made their own sailboats, so I
guess if you can say "I won't die if this breaks", go for it!

for further reading:
http://www.damonrinard.com/howibuil.htm

Quoted message said:

"Leo Lichtman" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"David Rees" wrote: (clip) I made a bike with 1 layer fiberglas and 1
layer CF, (clip)
^^^^^^^^^^^^^^^^^^^
You obviously have a handle on this. May I ask, what was the reason for
making the first layer out of fiberglas, and the second out of carbon?