Steel1

Hi. I am curious about an existing frame and its construction technique. It is a 1994 Ciocc in ELOS. The joints all look smooth and minimal, so maybe fillet braze.
But looking down the headtube, where the top-tube was joined, there is series of dots/bumps on inner surface of headtube in a circular pattern following the tube joint area.
I would have thought fillet braze would have been at a low enough temperature not to cause this (?).
If tig welded, could the builder file the welds smooth as to make it look like small fillet?
So what was the method used here?

Thanks in advance for your insight.

unterhausen

The penetration definitely suggests welding. It's unusual with steel, but maybe they did a cosmetic pass? They also could have gone back with brass to cover up the welding. Also, some Italian builders weren't afraid of a little bondo.

Maybe I should move this to C&V, someone has probably had the paint off of a bike like this. If it remains a mystery, you probably will get an answer if you write to Ciocc

guy153

Looks like TIG that's been filed (very carefully!) to me. I think they did sometimes do this. Remember reading about Indurain's Pinarello, or maybe it was Pantani's or somebody's where they did that.

unterhausen

That's why I was wondering if they did a cosmetic pass. The weld bead on steel is pretty small, usually. Although with all that melt-through, maybe they did just make big welds. I don't do tig, so I have no idea how hard that would be.

bulgie 

Yes you can control the size of the weld bead. A good example is the lugs Rob Roberson made for the 1961 Masi replica he made for Richard Byrne. He welded tubes together with big fillets, so he could file them to look like the stamped-sheetmetal lugs on the original.

The way Gary Helfrich taught me to weld Ti is another example, His signature move, with his Arctos frames and stems (that became the Ibis Ti stems) was big smooth fillets that are easy to smooth and polish until they disappear completely. A lot of work but man, what a look. I saw his sample at the Anaheim show (circa '91-'92) where he was hawking his Ti framebuilding class, and I was in love.

Mark B

unterhausen

So he didn't do a cosmetic pass for that? That seems a to be a lot more common approach.

bulgie 

He meaning Helfrich? Sort of, but the 2nd pass was done at the same time as the first. You weld a short section, short enough to stay under your torch cup, then back up over what you just welded, to flatten it. The fillet is still curved from tube to tube, I mean flat as in not a "stack of dimes", flat in the direction 90° from the tube-to-tube curve. Did I explain that OK? Very large torch cups are used, for best argon coverage, with a gas lens to make the gas come out in a laminar flow, without turbulence. You still can't weld very far before the still-hot metal is emerging out from under the torch, where it starts reacting with the atmosphere*. So this method is slow, for sure.

I only made a couple stems and one frame that way before I gravitated to a single-pass method that is much faster and with less heat input, but it doesn't lend itself well to smoothing and polishing, if that's the desired finish. I got bored with the polished welds — if you do them perfectly, then every one looks identical. Leaving welds unpolished seems more honest in a way. "Show your work".

* Ha, atmosphere, is that the people who follow Richard Sachs? Ugh, I need to get some sleep.

guy153

The weld bead is kind of as big as you want to make it, although if your fitup isn't perfect you don't have the option of a really small bead because feeding molten wire into fresh air will always result in something essentially spherical. You can then file that down if you want to (although if it looks so bad you have to I would call that a fail).

Some people I've seen on YT get a perfect fitup by machining the tubes (which may have been a less common approach back in the day) and then they do "pulse and lay wire" welds. You just lay the wire in the joint and zap over it with the machine set to pulse mode. This results in very tiny welds that are even slightly concave sometimes but easier to do if you are inexperienced. I don't trust them. If you were doing pulse+lay wire you might need multiple passes to get enough buildup to file it down again. But I think that's a pretty recent technique.

I suspect that in the early days of TIG frames the fitup wasn't as good, so the beads were a bit bigger, and people weren't accustomed to the look of weld beads, so they filed them. Those original Cannondale aluminium frames had the welds all ground down.

dsaul

That is definitely TIG welded. You can wash back over a weld with the TIG torch to smooth it out. All it takes is some high build primer and sanding to make it smooth enough to disappear under paint. I've never tried to wash back over a weld to make it smooth, but I have gone back over a weld using pulse or pulsing with the foot pedal to improve the appearance of a weld.

Steel1

Thanks for the insightful replies. I didn’t hear much pointing to fillet, so more likely tig with filing.

Mark Beaver

…and it may be unrelated but the first EL-OS I purchased back in the day had a head tube that was smaller OD than a standard OS head tube, I think the wall thickness was about 0.8 or 0.85, really thin. Perhaps this is the same head tube, that would explain the internal melt.