CS Hirose lug brazing video

[Jim G]

Curious what folks think of this

https://youtu.be/Wifpku15JqQ

From recent discussions here, it looks to my untrained eye that there's a lot of charred flux?  I also can't figure out why the torch flame is spraying out like that vs a tapered feather, seems like it's misadjusted, or maybe just a trick of the camera?

Thanks!

-Jim G

[Eric Keller]

he probably just doesn't feel like cleaning the tip, I know the feeling.  It was interesting to watch him pull brass through the lug out the other side.  He's really good at that, I don't think I would like using such a small amount of flux.  I have always said that if there is going to be an audience, you want to use more flux.  If a builder uses lfb, there is going to be carbon precipitating out of the steel.  The way it looks afterwards just depends on if there is flux there to carry it away or not. Since he doesn't put flux on the outside of his lugs, there is guaranteed to be carbon on the outside of the lugs.  It doesn't hurt anything. I'm pretty sure he sandblasts everything more than once.

There is charred flux and then there is charred flux.  Hirose is definitely very good at what he does.  His flux is not charred in any meaningful way. 

Eric Keller

Boalsburg, Pennsylvania

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[Hahn Rossman]

The other thing to notice is that despite getting the torch in real close he isn't overheating the brass and boiling the zinc out of it. There aren't any copper looking areas. 

I think one of the biggest improvements in my brazing was having Mark Bulgier recommend using a big bushy flame. In fact I use a small ride bud which helps get the whole area hot, but makes it easier to avoid localized overheating without all the frantic torch waving. There are plenty of ways to skin the cat, but the result needs to be good penetration without overheating and not spending too much time at temperature. I see a lot of beginners using to small a flame and spending way to much time. 

Hahn Rossman

[Jim Adney]

I've always loved those Nervex lugs, but that just about all that I could see to
recommend in this video. The split flame is due to some dirt in the torch tip.
Most people would have cleared that off with a flick of the rod across the tip
or a wipe of the tip across a firebrick. Either way, it's only a second to do.

On the down side:

There's not much flux. He heats up parts then switches hands to use his
hammer but by then the part is cold, but the hammer taps are only half
hearted, so they wouldn't have done much anyway. Some parts get really hot
and some parts seem to get heated over and over again. He spends a LOT
of time on the shorelines, but the heat is so local that it's not clear how much
penetration he's getting. It seems odd, and disappointing, that he feels the
need to go over the ends of the head tube as he finishes; those should have
been filled by penetration from above.

Just off hand, I'd say he spent more than twice as much time on these as he
should have. Oxy propane would have been better.

On the up side:

He keeps the torch moving. The parts that get overheated are the mild steel
lugs and usually not the tubes. As a result, the parts that end up really
burned appear to be the outside faces of the lugs, which really don't matter
much.

I watched his whole series of videos awhile back. I don't recall whether I
found his brazing as frustrating as I did today. I do remember being
impressed with his techniques and creativity for the accessories he does.
That may be his strength.

I'll be interested to hear what other people think.

--
*******************************
Jim Adney, jad...@vwtype3.org
Madison, Wisconsin, USA
*******************************

[Mike S.]

Now here's a flame.

https://www.youtube.com/watch?v=EuazU0IJUGA

Mike Scammon

Hood River, OR

[Hahn Rossman]

As long as we are sharing brazing videos here is Will working for Davidson brazing using oxy propane and a second torch to keep the joint hot on the other side and preheat. Its also a goo9d example of using preforms rather than adding filler. The rod in his hand is only to push the flux out of the way to verify the shorelines.

https://www.youtube.com/watch?v=ztXzoyYa45M

Hahn Rossman

[Mark Bulgier]

Hahn Rossman wrote:
As long as we are sharing brazing videos here is Will working for Davidson brazing using oxy propane and a second torch to keep the joint hot on the other side and preheat. It's also a good example of using preforms rather than adding filler. The rod in his hand is only to push the flux out of the way to verify the shorelines.
https://www.youtube.com/watch?v=ztXzoyYa45M
_________________________________________________

I guess having a video is better than no video, but man that “artistic” fading and superimposed images is annoying!

I think it’s not quite in real time, but we did get it down to reliably under 1:30 for a head lug, often less, 1:15 was common, and 1:00 is possible. That's from lighting the torch to turning it off. We cut a bunch of them up while perfecting the technique, so I can tell you for sure the penetration is 100%. Shorelines perfectly clean, no spatter or lumps, nothing to file.

We were using pretty thinwall tubes, down to .7/.4, and they had a very good reliability record, so we weren't hurting the tubes any. In fact I'm pretty sure "time at temperature" is important to the after brazing strength of the tube, lower being better, so those frames were probably stronger than ones brazed the trad slow way. Our calibrated destructive testing did indicate that too, so I'm not just guessing here. I mitered up a bunch of tubes and brazed sample joints in 531, Columbus and Prestige, with silver and brass, and the old slow way feeding the rod by hand from the outside, versus the fast way with brass preforms inside the joint. Then we crushed them all using Charlie Cunningham's frame crushing machine, which measures the force being applied. We took the number as when the tube first starts to buckle. Pretty fun. Thanks Charlie!

Pre-placed filler inside the joint is less important, but also helps with the speed and with the clean, spatter-free edges that don't need cleanup. Working out how to make and insert the pre-forms is a lot of work though.

Rick Gnehm was another Davidson framebuilder. He and I both ended up working for Match in the late '90s. Match founder Tim Isaac is an extremely experienced and talented framebuilder, but we disagreed on lug brazing. He liked a small flame and took probably more like 10 minutes to braze one lug. Rick and I mounted the biggest tips he had and turned it up about as big as it would go, and we still felt we were not gittin' 'er done as fast as we liked. We missed that second torch! I think we had to compromise on a medium-sized flame to not have Tim tearing his hair out in anguish. I don't think we ever completely won Tim over to the fast brazing style.

Match frames were tack brazed rather than being pinned, which limits how much of the lug you can have hot all at once. I think pinned joints brazed fast makes the best frame.

Martin Tweedy was there too and he's on this mailing list. Martin, does my story jibe with your recollection?

Mark Bulgier
Seattle

[Jim G]

On Thursday, November 16, 2017 at 10:56:31 AM UTC-8, Eric Keller wrote:

he probably just doesn't feel like cleaning the tip, I know the feeling.  It was interesting to watch him pull brass through the lug out the other side.  He's really good at that, I don't think I would like using such a small amount of flux.  I have always said that if there is going to be an audience, you want to use more flux.  

Yep if you watch his other videos, he doesn't seem to use much flux, and what he does use is thinned down to a VERY watery consistency. 

Thanks!

-Jim G

[Andy Newlands]

My two cents here.  When I visited the Marchetti factory in the 1980’s and Mr. Marchetti took us around to the Ciocc factory it was all brass preforms and carousal brazing.  Many thousands per year sold worldwide.  The beauty of brass brazing.  I imagine the vast majority stuck together rather well and that was before air hardening steels were around for cycle tubing.  Today air hardening steel like Reynolds 631 and the heat treated 853 gain strength in the HAZ when brass brazed so it makes even more sense to employ brass preforms.  Personally I’ve never tried using two torches at once as I am not sure how to scratch my nose at the same time but do use a Harris heating tip which puts out around 109,000 BTU with oxo-propane and all is good.

Cheers,

Andy Newlands

www.strawberrybicycle.com

www.torchandfile.com

www.oregonframebuilders.org

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[martin tweedy]

I have the same recollection as you Mark about brazing at match. Tim essentially taught me to braze so I have adopted many of his techniques. I recall on Ricks first day Curt and I were watching wide eyed as Rick got busy brazing with the biggest tip we had and the biggest and loudest flame we had ever seen.
I'd agree that a short, intense heat cycle is arguably the way to go if you have the proper technique.
While at Trek Tim instituted automated brazing and moved them from using silver to brass.
Martin

> On Nov 16, 2017, at 3:15 PM, Mark Bulgier <Ma...@bulgier.net> wrote:
>

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[John Clay]

The take home message, from this discussion and all the others over the years, would seem to be that the differences aren't really meaningful, within reason.

I don't braze like Hirose but I do focus the pre-heat on the lugs, minimizing flame wash onto the tubes, until the relatively large thermal masses (lugs or whatever) are near brazing temp. The result is that the tubes don't spend a whole lot of time above the critical temp. When using LP, which I never got comfortable with and discontinued, tubes and lugs got heated at the same time and for the same period. A larger portion of the tubes got heated as well. I'm not opining that this is better or worse, just where I've ended up and it seems a reasonable approach.

I settled on an AW206 tip adjusted per the "no soot before oxygen addition" method; the 206 because of acetylene cylinder withdrawal limitations, at least that's why initially. Subsequently I found that it can bring BB shells and other large masses up to temp pretty quickly if the large mass (read heat sinks) are preheated diligently, first. That, too, reduces time at temp for the tubes.

Just my observations and experiences.

John Clay
Tallahassee, FL