Which welds are better...
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  1. #1

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    Which welds are better...

    Alright guys and gals. Help me settle a debate with my friends...

    My two friends and myself all have engineering backgrounds but can't agree on this little subject. Which is bettter...hand welds or machine / robotic welds? I am of the presumption that robotic welds are better. Here is my argument...

    More accurate and predictable.
    Better tollerance.
    More consistant.
    Never subject to fatige or human error.

    They believe that a good welder can do better than an automated welder. Are they right or am I right? One issue I can't explain is why the higher end frames use mostly hand welds and not machine welds. This seems counter intuitive especially when the lower end bikes are make using robotic welding. I would think it would be the reverse if automated welding is as good as I am making it.

    Alright, thanks for the input!

  2. #2

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    This is a question w/ no answer. I think it'd be impossible to find a machine that does better welds than those that come out of the Moots factory. At the same time, I'm sure it'd be impossible to find welds done by a human that surpass those done by a well setup machine.

    There are too many variables to consider for any answer to this question. Which is better: part machined by a man on a Bridgeport or a part machined by a machine?

  3. #3

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    [QUOTE=Boise100]Alright guys and gals. Help me settle a debate with my friends...

    My two friends and myself all have engineering backgrounds but can't agree on this little subject. Which is bettter...hand welds or machine / robotic welds? I am of the presumption that robotic welds are better. Here is my argument...

    More accurate and predictable.
    Better tollerance.
    More consistant.
    Never subject to fatige or human error.

    Human error. Hmmm...

    I believe that machines are bad for some things, like building wheels, but good at other tasks like CNC machining (which, of course, requires a computer). As for welds on a frame, it all depends on the man/woman who programmed it and the quality inspection. Frankly, I'd rather have a fillet-brazed steel frame crafted by hands rather than some Taiwan robot alumnium or alu/carbon mix. Machines may be accurate but they are not always precise.

    And besides...do you really want a generic robot-welded frame for a bike? Most cars are made like this but what do car aficionados lust after? Something with the human touch.

  4. #4
    Arrogant roadie.....
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    Since you have engineering backgrounds, I would think the answer is obvious. Hand welding is more flexible. High end frames are often build to the customer's spec, something that would not make sense for a machine to do, what with all the settings needed to be entered for just one single frame.

    Have you ever programmed a robot? I've programmed an Adept robot before to just do simple assembly jobs, and let me tell you, it takes a minimum of a couple hours to program a robot for any task. A skilled welder can just weld the frame in much less time.
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  5. #5
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    Don't forget the enconomic point of view

    I am a software engineer and is currently working on my master degree in computer science. My undergraduate degree is BS in accounting. Well, so much about my background.

    In the enconomic point of view in today's business world, hand-made frames are more expensive than machine-made frames because of the labor cost and the "economic of scale" issues.

    (1) Labor cost argument:
    This is especially true here in the US. I belive most of these hand-made frames are made in the US where the average labor cost is higher than the rest of the world (except for some areas in Europe). As a result, hand-made frames are more expensive than machine-made frames.

    (2) Economic of scale argument:
    The faster you can finish a frame, the more frames that one can produce for a given period of time. Hence, the lesser the unit cost per frame. As a result, hand-made frames are more expensive than machine-made frames.

    My brief analysis only explains why hand-made frames are more expensive than machine-made frames. It doesn't answer you question of whether hand-made frames are of better quality than the machine-made frames.

    My 2 cents.

  6. #6

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    No comparision...

    Quote Originally Posted by Boise100

    They believe that a good welder can do better than an automated welder.
    Speaking as a human being that can actually weld, I don't think that there's any question that a human being welds better than a machine.

    The reason that robots weld as much as they do is due to the fact that most industrial applications don't require a super quality weld. Heck, a neophyte with a properly set up machine can stick two thick pieces of metal together and they will hold. It's doesn't have to be pretty to work. Robot welders are great at things like auto chassis, where they can lay down a good bead time and time again in the exact same way. Well, they an until something goes wrong, then they make the same mistake over and over and over again.

    But when it comes to a critical weld of thin metals, give me the human welder every time, especially in difficult TIG applications (like joining bicycle tubing). There you have a set of human eyes and ears constantly monitoring the process and making adjustments for changing conditions.

    -PV

  7. #7
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    Quote Originally Posted by plus_vite
    Speaking as a human being that can actually weld, I don't think that there's any question that a human being welds better than a machine.
    This is clearly an overstatement. I don't think there is any question that a well set-up machine will weld better than a human if the human is me, who has absolutely no experience. The fact is the best machine weld is better than the worst human weld. The best human weld is better than the worst machine weld. Both machine and huiman welds cover a wide range of quality and to really answer the original question a lot more information has to be provided to make the comparison meaningful.

  8. #8
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    My buddy is one of the guys who welds the Moots frames. There is no machine that can match his welds.

  9. #9
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    I assume that you are talking about tig welds here.
    The answer is simple......If you're making 100,000 franes a year, robotic welders are always better. You may have to throw away the first 50-100 frames until you get the machine set up correctly.
    .....................................If you're making 100-200 frames a year, hand welding of frames set up in a jig is always "better." If you're only making 200 frames a year, could you afford to ruin the first 50 ? Could you afford the cost of a robotic welder ?
    If your opinion differs from mine, ..........Too bad.
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  10. #10
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    I don't think anyone has ever posted anything on this board to prove that a human weld survives better than a machine weld.

    The high end frames never outlast the production frames on the rare engineering tests that get posted.

  11. #11
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    Define "Better"

    You really can't answer any question like this until the questioner defines what they mean by "better".

    Robots are probably better in the sense that:

    - They are able to produce more welds in a given amount of time
    - They are able to produce welds with near-identical or identcal precision
    - They are more cost-effective when mass-producing frames

    Humans are probably better in the sense that:

    - They can be vary their technique based on desired outcome or materials used
    - They can produce more visibly appealing welds
    - They are more cost-effective when producing small batches of frames

    I don't know of any study which analyzes the strength or lifecycle of either type of weld so, on that point, it's probably a draw.

    All that said, both robots and humans can produce welds which are crap and welds which are beautiful. So, pick whatever you like based on criteria important to you.

    - khill

  12. #12

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    You don't get it.

    Quote Originally Posted by asgelle
    This is clearly an overstatement. I don't think there is any question that a well set-up machine will weld better than a human if the human is me, who has absolutely no experience. The fact is the best machine weld is better than the worst human weld.
    A highly skilled welder equals or beats a robot every time!

    Even in situations where robots excel, a good welder will always be able to match or at least beat the robot in terms of weld quality (penetration, proper heating, aestetics, etc.). It just costs more to pay a good human welder than it does a machine.

    -PV

  13. #13
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    The vast vast vast majority of bikes have welds that are perfectly fine, they carry the bikes down the road for many thousands of miles with no issues.

    The real issues are:

    1) Why the hell do some people spend more time staring at the welds on their bike than riding?

    2) Don't you know your eyes are supposed to be watching the road as you ride, not staring at the welds on your bottom bracket?

    Aesthetic quality of welds has as much to do with whether the bike is going to be good as shaving your legs does with how fast you can ride.

  14. #14
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    Quote Originally Posted by khill
    You really can't answer any question like this until the questioner defines what they mean by "better".

    All that said, both robots and humans can produce welds which are crap and welds which are beautiful. So, pick whatever you like based on criteria important to you.

    - khill
    I think that you have to look beyond the pure mechanical aspect. A large manufacturer with a large advertising budget makes a run of 5000 high end frames. Because of the cost per unit, some bikes can be poorly constructed (check out some of the reviews of famous maker frames) and the company still turns a tidy profit. The vast majority of people who bought this product are satisfied, so the company's future is secure. What if someone like Brent Steelman, Bill Holland or Richard Sachs made frames using this philosophy? These frame builders sell a respectable amount of frames because people know exactly what they are getting and know that a human built the frame. When a frame is handbuilt and welded, every welding pass is checked for quality control. In a large factory using theory of constraints, there will be periodic quality checks in the process, but not at the level of a human welded frame. My money will always be spent on a frame that is hand welded. Dario Pegoretti does some nice work.

  15. #15
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    What makes bicycles so special that robots can't weld them correctly?

    Honda and Toyota are the most automated of any car manufacturers, and no one else except Porcshe is even playing the same game as they are. They are way, way, way out ahead of everyone else.

    Bicycles are apparently as hard or harder to make than race cars, motorcycles, fighter planes, spacecraft, etc... isn't it amazing?

    How many watts is a smoother weld worth?

  16. #16

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    Don't see what your beef is...

    Quote Originally Posted by benInMA
    The vast vast vast majority of bikes have welds that are perfectly fine, they carry the bikes down the road for many thousands of miles with no issues.

    Aesthetic quality of welds has as much to do with whether the bike is going to be good as shaving your legs does with how fast you can ride.
    The "aestetic quality" of the weld is very important. For instance, a good looking bead (to a knowledgable, skilled welder) is symptomatic of a high quality weld. Now, a weld can be ugly and still be viable, but the general and practical rule is that a good bead looks good. One thing we know for sure: bad welds are almost always ugly!

    Want to see an atrociously welded bike? Look at the new Schwinn Stingrays sold at various "big box" stores. The welding is hideous. The welds may be good enough to hold the frame together, but they are not high quality welds.

    Again, the work of a skilled human welder meets or exceeds the quality of any robot welder.

    I think it's great that we have some people who care about how the welding on their bicycle frames look. Not only does the aestetic aspect factor directly to the strength and durability of their frame, but it also rewards a highly skilled human being who can offer something that is nothing short of artistic.

    -PV

  17. #17
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    Yes but we've got people here who are agonizing over weld quality more than if they hurt their knee or something.

    There is almost nothing you can point to about a Merlin Weld vs. a Trek Weld vs. a Specialized Weld vs. a Richard Sachs weld which actually shows some to be better than others other than aesthetics.

    All of those bikes have shown their welds to be "good enough". As long as the bike does not fail or perform badly the welds are "good enough" and you should stop worrying about it.

    Bringing Walmart bikes into the equation is foolish. The point is almost all "bike shop" bicycles are welded good enough to last for a very, very long time.

  18. #18
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    Quote Originally Posted by benInMA
    There is almost nothing you can point to about a Merlin Weld vs. a Trek Weld vs. a Specialized Weld vs. a Richard Sachs weld which actually shows some to be better than others other than aesthetics.
    Except Richard Sachs's welds aren't. He brazes.

  19. #19
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    Yah my bad.. I was just trying to come up with a name that people spend mega $$$ for because of the craftsmanship.

  20. #20
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    BenInMA, I agree with you concerning machine welds. But then again, as long as they can cook and are decent in bed, I don't care what my wimmin look like, either.
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  21. #21
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    How many women could you woo with the time wasted worrying about welds?

  22. #22
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    This is actually quite intriguing...

    Im an engineer with a bit of welding experience, so we'll see how good it really is...


    Whoever quoted economy was bang on. 50 frames to set up the machine may be an understatement though. Probably 50 for each weld.... but that's besides the point.

    From my experience with robots and welding:

    Robots are fantastic, and in most cases, better than the parts that you feed to them. The robot WILL always produce a more consistent weld than a human, given the same part fit up. That is the key. The robot welded frames are jigged up, and the robot goes to town. Generally I dont think the big manufacturers use machine vision to track the weld line, which is essentially what the human does. In addition, if the human bungs up a weld, he probably grinds it off, and goes at it again. When the robot screws up - they can afford to scrap the frame.

    As for the automotive industry, I think they do mostly projection tack welds, and what could be called "easy" seams. Bikes are very thin tubes, and pretty difficult 3D seams.

    Personally, i prefer not to see the welds at all. I don't care who or what did them - polishing is craftsmanship.

    As far as strength goes. (Aside from huge flaws) both welds are the same.
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  23. #23
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    Will Robots???

    Will robots make better lovers. I'm already losing out to the rabbit

  24. #24
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    Welds and craftsmanship

    From a purely engineering standpoint, I'd bet that a robotic weld will nearly always be stronger than a hand-weld. Even the best welders can't make a weld that is stonger than the weakest part of the frame. Maybe the very best welders can make a marginally stronger weld than a machine, and of course, a poorly setup machine is also capable of making bad welds, but machine welds are certainly more reliably strong.

    OTOH, asthetically, there is no doubt that a hand weld can be better looking while also being quite strong. Furthermore, hand-working of a machine weld can also help asthetics without weakening the join.

    It's like watches: A $250 Seiko electronic watch can keep time as well or better than a $50,000 Patek Phillipe watch, but that isn't the point. A Seiko is a marvel of technology, wheras the Patek Phillipe is a marvel of craftsmanship.
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  25. #25

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    Quote Originally Posted by Dave_Stohler
    Even the best welders can't make a weld that is stonger than the weakest part of the frame. Maybe the very best welders can make a marginally stronger weld than a machine, and of course, a poorly setup machine is also capable of making bad welds, but machine welds are certainly more reliably strong.
    Gotta call BS on this one. Sorry, Dave.

    A good welder can equal or better the weld of just about any industrial robot welder. Every time! Human welders can most definitely make welds that are stronger than the base metal.

    You guys may know a little about bikes, but you don't know much about welding.

    -PV

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