Brazing

[Tom Kunich]

All of my brazing has been done with regular welding torches. But I may want to do some repairs on steel frames.

So my question is: Can you braze with a regular propane torch?

[AMuzi]

On 12/17/2022 1:48 PM, Tom Kunich wrote:
> All of my brazing has been done with regular welding torches. But I may want to do some repairs on steel frames.
>
> So my question is: Can you braze with a regular propane torch?
>

No, not hot enough.
But propane-oxygen is an excellent clean flame for brazing.

I prefer it for filling lugs and big castings such as BB and
crowns, where the time needed to properly fill would have
left much more dirt from acetylene.

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

[Tom Kunich]

I guess I'll either have to buy a new brazing setup or find someone with a setup I can use. Perhaps my older brother has my old tanks and torch in his garage.

[Tom Kunich]

I was told that while copper brazing is not possible with propane torches that they make a propane torch specifically for silver brazing and the sell the silver braze and flux on Amazon! My experience with silver brazing is that it appears to have all of the strength necessary to braze tube into lugs but it occurs at a lower temperature.

Would you disagree with that?

[AMuzi]

On 12/26/2022 11:11 AM, Tom Kunich wrote:
> On Saturday, December 17, 2022 at 2:06:01 PM UTC-8, Tom Kunich wrote:
>> On Saturday, December 17, 2022 at 12:19:07 PM UTC-8, AMuzi wrote:
>>> On 12/17/2022 1:48 PM, Tom Kunich wrote:
>>>> All of my brazing has been done with regular welding torches. But I may want to do some repairs on steel frames.
>>>>
>>>> So my question is: Can you braze with a regular propane torch?
>>>>
>>> No, not hot enough.
>>> But propane-oxygen is an excellent clean flame for brazing.
>>>
>>> I prefer it for filling lugs and big castings such as BB and
>>> crowns, where the time needed to properly fill would have
>>> left much more dirt from acetylene.
>>>

>> I guess I'll either have to buy a new brazing setup or find someone with a setup I can use. Perhaps my older brother has my old tanks and torch in his garage.
>
> I was told that while copper brazing is not possible with propane torches that they make a propane torch specifically for silver brazing and the sell the silver braze and flux on Amazon! My experience with silver brazing is that it appears to have all of the strength necessary to braze tube into lugs but it occurs at a lower temperature.
>
> Would you disagree with that?

How could I? I have no idea.

There are a wide range of silver braze materials at various
temperatures and characteristics (some of which are
unsuitable to our high alloy bicycle materials).

A handheld tank of propane with a torch tip screwed on

https://www.brandnew.net/wp-content/uploads/2020/10/PropaneTorch-JumboFlame-700x700.jpg

has a working temperature of roughly 1100F which is marginal
for silver work. I use one for lead fill and it's great for
that.

Oxy propane which we use for silver work has a peak of
2500F. We use it with a 1250F silver alloy filler.

Copper braze filler isn't used for bicycles generally. I've
only seen it in induction or oven brazing on an industrial
scale. Generally 1800F to 1950F and no advantages for
bicycles over the usual free flowing bronze fillers which
wet nicely at lower temperatures (mostly 1650F to 1750F).

[Tom Kunich]

Looking it up some more it isn't propane they are using but MAPP gas which has something other than propane in it to get a far hotter flame. This stuff is pretty expensive so it wouldn't be worth doing any extensive silver brazing with it.

[Jeff Liebermann]

On Mon, 26 Dec 2022 10:33:57 -0800 (PST), Tom Kunich
<cycl...@gmail.com> wrote:

>Looking it up some more it isn't propane they are using but MAPP gas
>which has something other than propane in it to get a far hotter
>flame. This stuff is pretty expensive so it wouldn't be worth doing
>any extensive silver brazing with it.

You claim to be worth nearly $2 million and you're worrying about the
cost of a bottle of MAPP gas? Two bottles are only about $40.

Note that MAPP gas changed formulation in 2008. The original was
better:
<https://www.amazon.com/BLUEFIRE-Cylinder-Variation-Quantity-Available/dp/B07NC5XC8H/>
Read the sellers bullet points.

I suggest you go with oxygen-acetylene instead of MAPP gas, unless
you're trying to go with the cheapest. If you don't have any
equipment (regulators, wrench, hoses, goggles, welding torches,
flashback arrestors, flux, tip cleaner, striker, welding rod, gloves,
etc), oxy-acetylene could become expensive. If you don't know how to
gas weld, which seems to be the case, you'll need to practice before
trashing the bicycle frame, which can consume considerable gas.

Something like these:
<https://www.amazon.com/s?k=oxygen+acetylene+torch+kit>
Figure on about $300 to $500 for everything from China including tanks
and cart.

If you're worried about consumables, silver brazing rod for steel is
not cheap:
<https://www.mcmaster.com/silver-brazing-rods/for-joining~steel/>

12/25/2022
<https://groups.google.com/g/rec.bicycles.tech/c/njA7DYpUtww/m/uTnjTb6DAwAJ>
"I'm worth nearly two million now and can live almost entirely on my
social security."

Good luck and try not to burn down the garage or house.

--
Jeff Liebermann je...@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

[Frank Krygowski]

On 12/26/2022 3:00 PM, Jeff Liebermann wrote:
> On Mon, 26 Dec 2022 10:33:57 -0800 (PST), Tom Kunich
> <cycl...@gmail.com> wrote:
>
>> Looking it up some more it isn't propane they are using but MAPP gas
>> which has something other than propane in it to get a far hotter
>> flame. This stuff is pretty expensive so it wouldn't be worth doing
>> any extensive silver brazing with it.
>
> You claim to be worth nearly $2 million and you're worrying about the
> cost of a bottle of MAPP gas? Two bottles are only about $40.
>
> Note that MAPP gas changed formulation in 2008. The original was
> better:
> <https://www.amazon.com/BLUEFIRE-Cylinder-Variation-Quantity-Available/dp/B07NC5XC8H/>
> Read the sellers bullet points.
>
> I suggest you go with oxygen-acetylene instead of MAPP gas, unless
> you're trying to go with the cheapest. If you don't have any
> equipment (regulators, wrench, hoses, goggles, welding torches,
> flashback arrestors, flux, tip cleaner, striker, welding rod, gloves,
> etc), oxy-acetylene could become expensive. If you don't know how to
> gas weld, which seems to be the case, you'll need to practice before
> trashing the bicycle frame, which can consume considerable gas.
>
> Something like these:
> <https://www.amazon.com/s?k=oxygen+acetylene+torch+kit>
> Figure on about $300 to $500 for everything from China including tanks
> and cart.

I wonder if it's possible to rent oxy-acetylene sets. I have my own, so
I've never looked into it. But I suspect renting, if possible, would
make sense for people who seldom use it.

Hmm. OK, locally, Rental Corral does rent "Welders - electric and gas."
But I'll bet the liability release is really something!

--
- Frank Krygowski

[AMuzi]

I worked in a frame shop which used oxy-MAPP. At that time
(1976) it was cheaper than acetylene but it's a dirty fuel.
Oxy propane is amazingly clean. Which matters for joint
quality and time spent in cleanup. You can buy a tank of
propane at your local service station ($25~35) which is
handy and a home hobby frame project won't use all that much
of it.

You'll need regulators hoses and a torch but hose sets are
not deathly expensive either.
new:
https://www.weldersupply.com/P/1175/PerformerMediumDutyOutfi

I don't know about small oxygen tanks but given the dramatic
rise in volume for medical purposes I would assume your
basic oxygen tank is affordable.

A quick web search shows a size E oxygen tank[1] can be
yours new for $60~75. I'd ask at your local welding and gas
supply about rental and refill prices before buying one.

Before you commit to anything take a few minute son craigslist:
https://detroit.craigslist.org/mcb/tls/d/utica-oxygen-acetylene-welding-brazing/7562900645.html

[1] These are the little ones you see strapped next to old
people on their electric wheelchairs in the grocery. We use
a standard size S which is about 4 feet tall; you don't need
anything like that.

p.s. Medical oxygen and welding oxygen aren't different for
your purposes. Only difference is sterile packaging.

p.p.s You can use an acetylene regulator for propane with a
brass tank adapter. No safety issues, just a different tank
thread size.

[John B.]

I use the standard "small" oxygen tank, which, as you say is perhaps 4
feet high. But here anyway, you don't buy a tank. You initially pay
for the tank and oxygen and from then on you take it in and trade it
for a full tank and pay only for the oxygen. If you don't want to use
oxygen any more you take the tank back and they refund your initial
payment for the tank.

The reference to "dirt" from an acetylene - oxygen torch seems a bit
odd, to say the least, as anyone that ever learned to weld with an
oxy-acetylene setup knows that you normally weld with a "neutral"
flame which leaves no crud at all.

Having said that I normally use an oxy-propane setup for brazing as I
already had a couple of small propane, actually cooking gas, tanks so
I didn't have to rent a acetylene tank and, I think, the cooking gas
is cheaper.
--
Cheers,

John B.

[Tom Kunich]

Since the kids gave me a propane BBQ, I always have a tank or two of unused propane around. Especially in the summer. I suppose I could buy regulators and hoses and a torch, but the idea was to eliminate as much of that as possible. I already have a lot of room absorbed by tools and such. If I do decide to build a fork, that is all it would be used for. I an not going to build a frame when there are so many good one's around for a song.

[John B.]

Strength of a brazed "lug" joint is largely dependent on the length of
the tub insertion into the lug and the clearance between the tube and
the lug.

In August 1982 "Bicycling Magazine's Newsletter for the Technical
Enthusiast" published a multi part dissertation on brazing that states
in part that "You'll notice that the tensile strength of the joint is
100,000 psi or greater for clearances between 0.001-0.005 inch".

Note that brass brazing is possible with oxygen-propane. there are
even you-tube movies on doing this.

Another note is that silver brazing material is available in a
multitude of types, temperatures and strengths. If I were a beginner
at this I would consult with someone (Andrew?) who has experience in
doing this.
--
Cheers,

John B.

[William Crowell]

After having done a lot of brazing over the years, I am now trying to learn how to MIG weld thin tubes and sheet metal panels by using a shielding gas and flux-less wire, because flux is exothermic and adds too much heat to the work. My test welds while using CO2 as the gas weren't too great, so I'm going to try 75% Argon/25% CO2 instead. I'm hoping that the Argon mix gas will work quite a bit better than the straight CO2.

[Tom Kunich]

On Tuesday, December 27, 2022 at 7:34:33 AM UTC-8, William Crowell wrote:
> After having done a lot of brazing over the years, I am now trying to learn how to MIG weld thin tubes and sheet metal panels by using a shielding gas and flux-less wire, because flux is exothermic and adds too much heat to the work. My test welds while using CO2 as the gas weren't too great, so I'm going to try 75% Argon/25% CO2 instead. I'm hoping that the Argon mix gas will work quite a bit better than the straight CO2.

I would like to be kept informed.

[John B.]

On Tue, 27 Dec 2022 07:34:31 -0800 (PST), William Crowell
<retrog...@gmail.com> wrote:

>After having done a lot of brazing over the years, I am now trying to learn how to MIG weld thin tubes and sheet metal panels by using a shielding gas and flux-less wire, because flux is exothermic and adds too much heat to the work. My test welds while using CO2 as the gas weren't too great, so I'm going to try 75% Argon/25% CO2 instead. I'm hoping that the Argon mix gas will work quite a bit better than the straight CO2.

You might want to read
https://weldguru.com/best-gas-for-mig-welding/

--
Cheers,

John B.

[Jeff Liebermann]

On Tue, 27 Dec 2022 07:34:31 -0800 (PST), William Crowell
<retrog...@gmail.com> wrote:

>After having done a lot of brazing over the years, I am now trying to learn how to MIG weld thin tubes and sheet metal panels by using a shielding gas and flux-less wire, because flux is exothermic and adds too much heat to the work. My test welds while using CO2 as the gas weren't too great, so I'm going to try 75% Argon/25% CO2 instead. I'm hoping that the Argon mix gas will work quite a bit better than the straight CO2.

What grade of CO2 did you use for testing?
<https://www.co2meter.com/blogs/news/co2-purity-grade-oxygen-purity-grade-charts>
"Industrial applications like welding utilize 99.5% pure CO2. In
welding, higher purity CO2 produces better welds because the process
is heating less impurities in the process. Those impurities have been
found to produce less stable welds."

When I tried MIG welding using carbonation gas from a soda pop
machine, the results were marginal. It wasn't weld contamination that
gave me trouble but rather the tiny amount of water in the gas would
explode and produce a porous weld. Water expands about 800x when
vaporized, so you can imagine the mess it created. I also had a
difficult time maintaining the arc. Other than looking like a sponge
under a microscope, the weld seemed acceptable. I didn't try a purer
grade of CO2 because none was available at the time.

"MIG Welding with 100% Co2 Shielding Gas"
<https://weldguru.com/mig-welding-with-100-co2/>
See section under "consumables".

[John B.]

On Tue, 27 Dec 2022 16:15:22 -0800, Jeff Liebermann <je...@cruzio.com>
wrote:

err... the usual test of a weld is to bend the test strips double
parallel with the weld bead to see whether the weld is as strong as
the parent metal :-)

And yes, in my younger days I was a USAF certified welder TIG (steel,
aluminum) and Stick (horizontal and vertical).
--
Cheers,

John B.

[Tom Kunich]

I should add that you're talking about MIG welding which implies metals other than steel. In order to maintain the strength of steel you don't want to overheat it meaning that brazing is an acceptable means of dealing with it if possible. The fork I intend to build has lugs and therefore, is a good candidate for brazing. At the moment I am looking in Craigslist for a cheap brazing rig. But prices of everything have gone up faster than gold.

[AMuzi]

Uh, not at all-

https://www.millerwelds.com/resources/article-library/mig-welding-the-basics-for-mild-steel

[John B.]

The normal certification schedule for both stick and TIG welders when
I certified, and it is probably the same today, included stick welding
of steel and TIG welding of steel and aluminum.

Some people appear to have rather bizarre notions.
--
Cheers,

John B.

[John B.]

Really Tommy? Steel shouldn't be heated? Strange then that so many
"steel" things are welded, isn't it? Or is it like "Communism" and
"lefties" you simply don't know what "steel" is?
--
Cheers,

John B.

[Doug Landau]

> >I should add that you're talking about MIG welding which implies metals other than steel. In order to maintain the strength of steel you don't want to overheat it meaning that brazing is an acceptable means of dealing with it if possible. The fork I intend to build has lugs and therefore, is a good candidate for brazing. At the moment I am looking in Craigslist for a cheap brazing rig. But prices of everything have gone up faster than gold.
> Really Tommy? Steel shouldn't be heated? Strange then that so many
> "steel" things are welded, isn't it? Or is it like "Communism" and
> "lefties" you simply don't know what "steel" is?

Is this not why bicycles were until recently brazed, and this in turn why lugged? Because brazing is lower temp and thus -hopefully- is completed without taking the temper out of the heat-treated tubes?
I would suspect that it's not a concern w.r.t. dropouts, or not nearly as bad... cuz of their size and shape, they perhaps a)don't need to be hardened, and b)don't heat up nearly as fast as thin walls of tubing?

[Doug Landau]

> > So my question is: Can you braze with a regular propane torch?
> >
> No, not hot enough.
> But propane-oxygen is an excellent clean flame for brazing.
>
> I prefer it for filling lugs and big castings such as BB and
> crowns, where the time needed to properly fill would have
> left much more dirt from acetylene.

What I don't understand is how u get the shit to stick! I took an old bike frame, don't remember how i prepped the joint, took a thin brass rod and used a #0 tip, probably, using oxy-acet, heated the work , heated the rod and dipped in in a tin of flux, and ... could not get the brass to stick to the steel, it just ran right off.
I am pretty sure I successfully brazed in HS shop, and definitely sure I successfully silver-soldered. What I was using looked like brass to me and failed the magnet test. Was i using the wrong rod, the wrong flux, or did not prep correctly the area of the old frame?

[Frank Krygowski]

My guess: Improper prep. We'll see what Andrew says. He's the expert.

- Frank Krygowski

[John B.]

Most modern bicycle tubing is made of alloys that are designed to
allow brazing, or in some cases welding without appreciable loss in
strength.

Columbus Niobium, for example, states "Material suggested for TIG
welding" and then specify's the recommended TIG rod to use.
--
Cheers,

John B.

[John B.]

Generally one applies flux to the joint and then heats the fluxed
joint until the flux liquefies at about the temperature that the rod
melts.

It works best if the joint is first cleaned to "bright metal".
--
Cheers,

John B.

[William Crowell]

When I took a bicycle-building class from Albert Eisentraut in 1976, the hot ticket for brazing was the jet fluxer, a tank filled with liquid flux that was inserted into the acetylene line. Eisentraut recommended that we buy one, so I did. Some people call them brazing flux generators. I still have my jet fluxer and use it pretty often when I want to braze at as low a temperature as possible.

[AMuzi]

Too many variables within 'bicycles' to generalize.

Modern air-hardening steels are designed for TIG processes
whereas classic (postwar through the 1990s) materials were
virtually unweldable. Even on a TIG frame, frame ends are
commonly (not always) joined in silver or bronze.

And then there are QC errors; sloppy technique, poor miters
and fit, joined under tension, dirt in joint, etc. These
are separate from theory and design usually.

[AMuzi]

How clean was the substrate? Emery or a nylon wheel to a
bright finish is good practice. Where practicable an acid
wash and then neutralization is very good. Steel wire power
brushes can leave a burned residue that repels bronze or
silver. Media blasting needs a very thorough cleaning as
the media is in the grain of the substrate. etc, etc.

Also, did you heat the work until the flux melted before
joining and the flux you chose match the filler temperature?

https://www.machinemfg.com/brazing/

note especially #3 on the 2d list, "High requirements for
preparation before welding, especially surface quality and
assembly joint clearance"

[Tom Kunich]

The tubes have to be prepped by sanding them or chemically etching them clean and you have to use flux which helps the bronze to adhere to the steel. As a rule, like metals will mix but you need flux to mix dissimilar metals. And you have to use the correct flux for the job and you cannot overheat the flux which is usually shown by it burning or turning black. From my memory damage I can't remember where I learned rather complete welding and brazing, but it is just like programming - when I sat down in front of the computer everything just came back.

But after pricing a welding/brazing outfit I think I will just take it to one of the craigslist people who would do this for a third the price and I won't have the tanks and stuff to find a place for in my garage.

[Tom Kunich]

The poor miters are especially a problem with the soft brazing metals like silver. I remember having to EXACTLY get the miters correct. This was done on a boring machine with the correct sized bit. Some people would try to use a cutter that would push the metal around and the fit would not be very close. You could get away with this with Bronze braze and building up the area but softer brazes would fail over time. Thinking about it now, I remember all of this from working with a guy building record drag motorcycles. We used bicycle tubes. He would do the end to end welding and I could do the brazing. I think that Goodyear made special tires for us.

[AMuzi]

Mr Krygowski has shared his experience with amateur fork
builders. It was not a pleasant experience.

[Tom Kunich]

Well I would hardly trust fork construction to someone that can't build a safe frame.

[Lou Holtman]

> Open every day since 1 April, 1977

Exactly what I was thinking. I can't understand why Tom would not follow your advice and get a fork from Waterford(?) for 400 dollar especially with his history.

Lou

[Tom Kunich]

Lou, you sound like you have a fear of breaking a carbon fork. Steel is quite different and if you have the correct components a safe fork is quite easy to make. I have absolutely no fear of a steel fork that I would make. Steel is not carbon fiber.

[Frank Krygowski]

On 1/1/2023 7:55 AM, William Crowell wrote:
> When I took a bicycle-building class from Albert Eisentraut in 1976, the hot ticket for brazing was the jet fluxer, a tank filled with liquid flux that was inserted into the acetylene line. Eisentraut recommended that we buy one, so I did. Some people call them brazing flux generators. I still have my jet fluxer and use it pretty often when I want to braze at as low a temperature as possible.

That's how our custom tandem was built. It seemed like a really good
system, but I never got to try it myself.

--
- Frank Krygowski

[Lou Holtman]

I have no fear breaking MY carbon forks.

Lou

[Frank Krygowski]

On 1/1/2023 11:50 AM, AMuzi wrote:
>
> Mr Krygowski has shared his experience with amateur fork builders. It
> was not a pleasant experience.

Sadly, the guy who built our tandem was not an amateur. He was pretty
well respected, although when our fork broke and I contacted Tandems
Limited about a replacement, Jack Goertz of TL said "I always told him
his forks weren't strong enough."

Again, the fork we got was even worse. He used track gauge instead of
tandem gauge fork blades, so the wall thickness was one third what it
should have been. I think that happened because he was rushing to finish
the bike before his honeymoon trip to Europe. I think he used whatever
blades he had on hand.

Don't have Jim Bradford build your forks. And don't have anyone build
your forks if they're on their way to their honeymoon.

--
- Frank Krygowski

[AMuzi]

On 1/1/2023 11:36 AM, Tom Kunich wrote:
> On Sunday, January 1, 2023 at 9:31:00 AM UTC-8, Lou Holtman wrote:
>> On Sunday, January 1, 2023 at 5:50:15 PM UTC+1, AMuzi wrote:
>>> On 1/1/2023 10:31 AM, Tom Kunich wrote:
>>>> On Saturday, December 31, 2022 at 7:50:33 PM UTC-8, doug....@gmail.com wrote:
>>>>>>> So my question is: Can you braze with a regular propane torch?
>>>>>>>
>>>>>> No, not hot enough.
>>>>>> But propane-oxygen is an excellent clean flame for brazing.
>>>>>>
>>>>>> I prefer it for filling lugs and big castings such as BB and
>>>>>> crowns, where the time needed to properly fill would have
>>>>>> left much more dirt from acetylene.
>>>>> What I don't understand is how u get the shit to stick! I took an old bike frame, don't remember how i prepped the joint, took a thin brass rod and used a #0 tip, probably, using oxy-acet, heated the work , heated the rod and dipped in in a tin of flux, and ... could not get the brass to stick to the steel, it just ran right off.
>>>>> I am pretty sure I successfully brazed in HS shop, and definitely sure I successfully silver-soldered. What I was using looked like brass to me and failed the magnet test. Was i using the wrong rod, the wrong flux, or did not prep correctly the area of the old frame?
>>>>
>>>> The tubes have to be prepped by sanding them or chemically etching them clean and you have to use flux which helps the bronze to adhere to the steel. As a rule, like metals will mix but you need flux to mix dissimilar metals. And you have to use the correct flux for the job and you cannot overheat the flux which is usually shown by it burning or turning black. From my memory damage I can't remember where I learned rather complete welding and brazing, but it is just like programming - when I sat down in front of the computer everything just came back.
>>>>
>>>> But after pricing a welding/brazing outfit I think I will just take it to one of the craigslist people who would do this for a third the price and I won't have the tanks and stuff to find a place for in my garage.
>>>>
>>> Mr Krygowski has shared his experience with amateur fork
>>> builders. It was not a pleasant experience.

>> Exactly what I was thinking. I can't understand why Tom would not follow your advice and get a fork from Waterford(?) for 400 dollar especially with his history.
>>
>> Lou
>
> Lou, you sound like you have a fear of breaking a carbon fork. Steel is quite different and if you have the correct components a safe fork is quite easy to make. I have absolutely no fear of a steel fork that I would make. Steel is not carbon fiber.
>

Both materials have their failure rates (as does every
thing) but the rate is higher in steel than in carbon.

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

[Tom Kunich]

Lou, that is entirely your judgement. I have watched the sag wagons on the Tour cleaning up carbon bikes broken into bits. Eneos sued their bike sponsor for endangering their riders. But I suppose it is a matter of choice.

[Tom Kunich]

So when was the last time you saw a Colnago Super or Mexico fail?

[John B.]

The last time I certified as an Air Force Aircraft welder the test
supervisor had the aluminum test pieces soaking in some sort of
chemical bath to ensure that they were "CLEAN!" It is important!
--
Cheers,

John B.

[AMuzi]

Forks, not recently. Frames regularly.
http://www.yellowjersey.org/photosfromthepast/col162d.jpg

Which implies you'd do well to buy a Colnago fork.

[John B.]

If, as you say, "a safe fork is quite easy to make" why all the posts
from a "Tom Kunich" about how to put a steel fork together?
--
Cheers,

John B.

[AMuzi]

On 1/1/2023 6:13 PM, John B. wrote:
> On Sun, 1 Jan 2023 09:36:53 -0800 (PST), Tom Kunich
> <cycl...@gmail.com> wrote:
>
>> On Sunday, January 1, 2023 at 9:31:00 AM UTC-8, Lou Holtman wrote:
>>> On Sunday, January 1, 2023 at 5:50:15 PM UTC+1, AMuzi wrote:
>>>> On 1/1/2023 10:31 AM, Tom Kunich wrote:
>>>>> On Saturday, December 31, 2022 at 7:50:33 PM UTC-8, doug....@gmail.com wrote:
>>>>>>>> So my question is: Can you braze with a regular propane torch?
>>>>>>>>
>>>>>>> No, not hot enough.
>>>>>>> But propane-oxygen is an excellent clean flame for brazing.
>>>>>>>
>>>>>>> I prefer it for filling lugs and big castings such as BB and
>>>>>>> crowns, where the time needed to properly fill would have
>>>>>>> left much more dirt from acetylene.
>>>>>> What I don't understand is how u get the shit to stick! I took an old bike frame, don't remember how i prepped the joint, took a thin brass rod and used a #0 tip, probably, using oxy-acet, heated the work , heated the rod and dipped in in a tin of flux, and ... could not get the brass to stick to the steel, it just ran right off.
>>>>>> I am pretty sure I successfully brazed in HS shop, and definitely sure I successfully silver-soldered. What I was using looked like brass to me and failed the magnet test. Was i using the wrong rod, the wrong flux, or did not prep correctly the area of the old frame?
>>>>>
>>>>> The tubes have to be prepped by sanding them or chemically etching them clean and you have to use flux which helps the bronze to adhere to the steel. As a rule, like metals will mix but you need flux to mix dissimilar metals. And you have to use the correct flux for the job and you cannot overheat the flux which is usually shown by it burning or turning black. From my memory damage I can't remember where I learned rather complete welding and brazing, but it is just like programming - when I sat down in front of the computer everything just came back.
>>>>>
>>>>> But after pricing a welding/brazing outfit I think I will just take it to one of the craigslist people who would do this for a third the price and I won't have the tanks and stuff to find a place for in my garage.
>>>>>
>>>> Mr Krygowski has shared his experience with amateur fork
>>>> builders. It was not a pleasant experience.

>>> Exactly what I was thinking. I can't understand why Tom would not follow your advice and get a fork from Waterford(?) for 400 dollar especially with his history.
>>>
>>> Lou
>>
>> Lou, you sound like you have a fear of breaking a carbon fork. Steel is quite different and if you have the correct components a safe fork is quite easy to make. I have absolutely no fear of a steel fork that I would make. Steel is not carbon fiber.
>
> If, as you say, "a safe fork is quite easy to make" why all the posts
> from a "Tom Kunich" about how to put a steel fork together?
>

Why not? What ever could go wrong?

http://www.yellowjersey.org/photosfromthepast/failfork.jpg
http://www.yellowjersey.org/fkpardo.jpg
http://www.yellowjersey.org/photosfromthepast/fkbs19a.jpg
http://www.yellowjersey.org/axsfk16.jpg


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

[John B.]

Good Lord! Is the quality of the work that you do?
--
Cheers,

John B.

[AMuzi]

Those are all 'before' pictures.

Undoing and rectifying build errors, crashes, corrosion and
the vicissitudes of time are pretty much what I do all day.

[John B.]

Yes, I was being a "smart ass".

But do you find a lot of building errors? I have one bike, built in
Japan I think, that must have been 20 years old when I bought it and
with no corrosion (that I could find) in the tubes and no failures in
joints. I did replace the wheels and I think I remember the head
bearings, and other then that painted the thing. and it' still going.
--
Cheers,

John B.

[AMuzi]

No, I do not. They are rare oddities. Which is why they are
interesting.

[funkma...@hotmail.com]

My Easton EC90 from 2002 on my commuter finally failed this year, unfortunately while I was riding it. I hit a rough patch of road and the front wheel all but locked up, fortunately I has shifted my weight back such that it didn't toss me over the bars, on flat ground, I don't think I was going much more than 18mph or so. It wasn't the carbon that failed, it was the aluminum dropout - it sheared right at the point it inserts into the carbon leg leaving the aluminum tab still epoxied into the carbon. As far as I could tell, the carbon appears undamaged.

That fork has been on various racing and non-racing builds, I would estimate it has well over 50,000 miles.

[Tom Kunich]

I have has hundreds of steel bikes and have never seen a failure., I did see some failures in department store bikes But those are not made for reliability but for pure cheap utility.

[Tom Kunich]

I suppose that in your business you see the very worst cases and can present those but they are so rare that they certainly would never appear in most other bike shops.
To compare the failure rate of carbon fiber bikes, most of which are reasonably new with 30 year old steel bikes though couldn't possibly make a carbon fiber frameset look good by any stretch of the imagination.

I remember ONE good steel bike failure and it was a custom made Steelman. It had a break in the top tube at the head tube. And it had clearly been overheated. And the break occurred less than a month after the owner had it delivered.