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legrandefromage":1zecxr99 said:
Is that why some of the Yeti’s out there have an industrial look about the welding rather than pretty boy welds as seen in the Fat,
Function rather than form... (sums up F.R.O)
Relative benefits of welding vs brazed lugs vs fillet braze
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Is that why some of the Yeti’s out there have an industrial look about the welding rather than pretty boy welds as seen in the Fat,
Function rather than form... (sums up F.R.O)
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danson67 always explains it better!
I'll try: ones done by a machine (pulse welder) and the other by 'hand'. Taiwanese frames look neat but that neatness can mask poor joins whereas the the slower less time efficient 'hand' weld can follow the tubing better and create better stronger joins.
I'll try: ones done by a machine (pulse welder) and the other by 'hand'. Taiwanese frames look neat but that neatness can mask poor joins whereas the the slower less time efficient 'hand' weld can follow the tubing better and create better stronger joins.
M-Power
Old School Grand Master
legrandefromage":2140yjlr said:
Of course but when its done by one of the very best of the retro era and most of his frames are still around ‘unrepaired’ being hammered 25-30yrs later, you can take it as read that they were done right. Its a complex science when you get into it. Gary Helfrich ( ex MIT too ) was the head welder at FAT before Scotty B
I read posts by an ex RM staffer, that many of the Ti Rocky Mountain bikes had weld failure issues but there are still afew of these beauties around.
Almost all of the difference in weld appearance and quality is down to settings, method and ultimately the human holding the torch and filler rod.
They can all produce perfectly good structural weld, pretty or not....or a terrible one that will fail.
For Ti, tacking then single pass laywire technique with auto-pulsing (which looks like the Fat above, also Merlin, Litespeed and Kish) tends to give a slightly less regular weld as heat input, pool volume, width, feed rate, penetration and spacing all need to be controlled at the same time with only one chance to get it right. However, it is quicker and less expensive, with only one heating phase with less risk of stresses building up, misalignment, hydrogen contamination, etc.
Some builders, such as Moots, Eriksen, Engin and Firefly tack, then run an initial fusion run (little or no filler, just melting the tube material) to join the tubes, ensuring good penetration. This is followed by a second essentially cosmetic pass of laywire to cover the fusion pass. This method involves 2 major heating phases, basically welding the frame twice, so is costly in time and purging etc, but produces the extremely even-looking welds that buyers like these days.
2 pass welding does also have a higher risked of distortion and contamination, given the 2 heating phases, longer time at elevated temperatures and handling, so requires more rigorous and consistent weld mapping to keep everything straight...Ti does not like being 'cold set'.
Both these methods produce a single continuous ribbon of even weldment with a good, well-penetrated root in Ti.
Some steel frames are welded by laywire in a single pass on a higher pulse frequency (20+ Hz) so have good penetration consistency and an even 'caterpillar' look to the weldment. Most Taiwanese builds are like this. However some builders and customers prefer the widely 'stacked dimes' look of a slow (1 second ish) pulse with a dipped filler rod.
This gives distinct flat circular steps in the weldment. The weld pool is heated, filler rod added, then cooled in each 1 second phase, then the welder moves the torch along for the next pulse.
Because the pool is cooled during each phase, heat input is easier to control than with laywire (which is good), but if care isn't taken to make sure that the individual pools overlap properly, there can be voids, cooling cracks and no fusion between the two tubes.
Aluminium is a whole different set of trouble with AC, +/- balance, waveform, hf and lf pulsing...
All the best,
They can all produce perfectly good structural weld, pretty or not....or a terrible one that will fail.
For Ti, tacking then single pass laywire technique with auto-pulsing (which looks like the Fat above, also Merlin, Litespeed and Kish) tends to give a slightly less regular weld as heat input, pool volume, width, feed rate, penetration and spacing all need to be controlled at the same time with only one chance to get it right. However, it is quicker and less expensive, with only one heating phase with less risk of stresses building up, misalignment, hydrogen contamination, etc.
Some builders, such as Moots, Eriksen, Engin and Firefly tack, then run an initial fusion run (little or no filler, just melting the tube material) to join the tubes, ensuring good penetration. This is followed by a second essentially cosmetic pass of laywire to cover the fusion pass. This method involves 2 major heating phases, basically welding the frame twice, so is costly in time and purging etc, but produces the extremely even-looking welds that buyers like these days.
2 pass welding does also have a higher risked of distortion and contamination, given the 2 heating phases, longer time at elevated temperatures and handling, so requires more rigorous and consistent weld mapping to keep everything straight...Ti does not like being 'cold set'.
Both these methods produce a single continuous ribbon of even weldment with a good, well-penetrated root in Ti.
Some steel frames are welded by laywire in a single pass on a higher pulse frequency (20+ Hz) so have good penetration consistency and an even 'caterpillar' look to the weldment. Most Taiwanese builds are like this. However some builders and customers prefer the widely 'stacked dimes' look of a slow (1 second ish) pulse with a dipped filler rod.
This gives distinct flat circular steps in the weldment. The weld pool is heated, filler rod added, then cooled in each 1 second phase, then the welder moves the torch along for the next pulse.
Because the pool is cooled during each phase, heat input is easier to control than with laywire (which is good), but if care isn't taken to make sure that the individual pools overlap properly, there can be voids, cooling cracks and no fusion between the two tubes.
Aluminium is a whole different set of trouble with AC, +/- balance, waveform, hf and lf pulsing...
All the best,
doctor-bond
Feature Bike
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Brilliant stuff Dan. Just the sort of factual info needed here.
Brilliant stuff Dan. Just the sort of factual info needed here.
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Told you he'd do it better
M-Power
Old School Grand Master
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You cant beat expert opinion, cheers Dan My money is still on single pass laywire with auto-pulsing by a master crafstman. Interesting to hear how Moots and Firefly get such robotically perfect welds. People clearly prefer the perfect robot welded look these days.
You cant beat expert opinion, cheers Dan
My money is still on single pass laywire with auto-pulsing by a master crafstman. Interesting to hear how Moots and Firefly get such robotically perfect welds. People clearly prefer the perfect robot welded look these days.
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Danson FTW
Danson FTW
ultrazenith
Senior Retro Guru
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Great answers, especially Danson!
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Re: Re:
D T W
brocklanders023":if75g7xv said:Danson FTW
D T W
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