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  1. #1
    Senior Member RoboMonkey's Avatar
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    Steel Frame Disassembly

    I am trying to take apart a steel frame, and right now I am working on the top tube. I cut the top tube at the upper headtube lug and I am trying to heat the seat lug and pull the top tube out. This does not seem to be working, it doesn't move at all when I try to turn/pull it when the lug is heated up. Any tips? Would it be better to cut the tube and grind the extra out?

  2. #2
    Bicycle Repair Man !!! Sixty Fiver's Avatar
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    Issue may be that you are not getting enough even heat to the lug to get it hot enough to release... it is a lot of area to heat up at once.

    Removing tubes from the head lug also involves a good deal of work as they can resist disassembly.

  3. #3
    Randomhead
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    I agree with SixtyFiver. What are you using for heat? What kind of bike is it? If it was originally put together with bronze, you are in for a tough time. Are you sure the joints weren't pinned?

  4. #4
    Old fart JohnDThompson's Avatar
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    Yes, removing a tube takes a lot more heat than brazing it in place originally. Use the biggest tip you have, preferably a "rosebud" type tip and keep the entire joint molten while pulling. A trick Tim Isaac used was to drill holes in the tube stumps, stick a rod through the holes and use a bungie cord to supply the "pull" while you heat the joint. Once the tube is out, position the lug with the socket facing down and use a solder wick to pull out as much brass/silver as possible. This will make the clean-up much easier when fitting the replacement tube.

    And yes, check for pins before you start, otherwise you'll destroy the lugs when you try to pull the tubes. If you find pins you can drill them out before breaking out the torch.
    Last edited by JohnDThompson; 10-28-11 at 11:48 AM.

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    Bicycle Repair Man !!! Sixty Fiver's Avatar
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    Quote Originally Posted by unterhausen View Post
    I agree with SixtyFiver. What are you using for heat? What kind of bike is it? If it was originally put together with bronze, you are in for a tough time. Are you sure the joints weren't pinned?
    Have taken apart a few Kuwahara head tubes as practice and to salvage lugs... they seem to have liked using bronze instead of brass.

    Good point about checking for pins as these also have to be removed.

  6. #6
    Randomhead
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    I don't know if there were any manufacturers other than Trek that used silver on a significant number of frames.

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    Bicycle Repair Man !!! Sixty Fiver's Avatar
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    Quote Originally Posted by unterhausen View Post
    I don't know if there were any manufacturers other than Trek that used silver on a significant number of frames.
    On a production scale... no.

    Small builders... definitely.

    Most of our production uses brass and focus is on filet brazed frames rather than lugged although we can make a pretty nice silver brazed lugged frame which is actually far less work.

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    Randomhead
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    Considering there are millions of bikes made in a year, you could make a reasonable argument that the number of bikes Trek put together with silver isn't a significant number.
    Maybe Serrotta has put together as many frames with silver as Trek did.

    Since the OP didn't say what he was taking apart, I figured it wasn't a custom build

  9. #9
    Bicycle Repair Man !!! Sixty Fiver's Avatar
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    Quote Originally Posted by unterhausen View Post
    Considering there are millions of bikes made in a year, you could make a reasonable argument that the number of bikes Trek put together with silver isn't a significant number.
    Maybe Serrotta has put together as many frames with silver as Trek did.

    Since the OP didn't say what he was taking apart, I figured it wasn't a custom build
    Thought we were just talking shop... while we wait for the OP to tell us what he is taking apart.

    Do not think that many larger builders ever used silver to any great extent... when you factor the cost of brass compared to silver it makes a big difference on a production level.

  10. #10
    Randomhead
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    the way the speculation in silver is going, it may be a thing of the past. I recently taught myself to braze lugs with bronze, just in case

  11. #11
    Senior Member RoboMonkey's Avatar
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    My goal at the moment is to make a bike frame, but I also wanted to practice taking apart frames because I have another somewhat nicer frame that needs to have its top tube replaced.

    The bike I am taking apart a KHS classic. It appears to have been put together with bronze, but I am not sure. I don't see any pins in the lugs. I attempted to remove the tube from the lug, the lug got warped a lot. It looks like I will have to buy new lugs, but I will be able to use all the tubes, bottom bracket shell and dropouts from this frame. It looks like I will have to practice more before I can attempt to repair my nicer frame.

    Would there be any reason, aside from aesthetic ones, I couldn't use these lugs from Nova in a frame?

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    Randomhead
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    those lugs would work fine. I would try to make them look better, thin them, possibly braze on extensions.

    Disassembling a lug that is brazed with bronze is going to take quite a bit of heat and a lot of patience. It's easy enough to destroy a lug brazed with silver.

  13. #13
    Senior Member GrayJay's Avatar
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    Quote Originally Posted by RoboMonkey View Post
    Would there be any reason, aside from aesthetic ones, I couldn't use these lugs from Nova in a frame?
    Just a bit unusual to have OS frame tube sizes with a 1" steer tube. If you are trying to use these with your salvaged tubes just make sure the lug and tube sizes match. The stamped seatpost binder ears on those lugs look pretty cheap and are somewhat fragile. YOu might also consider the Nova November monthly special tube+lugset+bb, good parts and a good value if you wanted to build a standard diameter frame.

  14. #14
    Senior Member RoboMonkey's Avatar
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    Quote Originally Posted by unterhausen View Post
    Disassembling a lug that is brazed with bronze is going to take quite a bit of heat and a lot of patience. It's easy enough to destroy a lug brazed with silver.
    It seems like it. Luckily, I have found a damaged frame that I can practice on if I need to.

    Quote Originally Posted by GrayJay View Post
    Just a bit unusual to have OS frame tube sizes with a 1" steer tube. If you are trying to use these with your salvaged tubes just make sure the lug and tube sizes match.
    I just noticed I linked to the wrong set of lugs. Nova has another set of standard size lugs, which are the ones I want. I will wait to see what the November special is before ordering I think.

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