Frame Building questions

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by tgaydos, Jan 27, 2016.

  1. MEASURE TWICE

    MEASURE TWICE Active Member

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    I've been using a Hobart MIG ready 130 with additional regulator for AR CO2 bottle and have been happy with it. For TIG you do spend more. I've used both. MIG if you buy should be one with a continuously variable amps control. I think with just A B C D settings I can not control low enough amps for very thin metal. This picture is of around 1/4 inch which it says it cannot do that thick in the instructions. I just go slower and made it work. Also you can make edges V shape for easier heat penetration and fill.
     

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  2. 1hp

    1hp New Member

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    +1 ^^ (cant 'like' on this forum ?) i am glad my mig had continuously variable settings , even the slightest adjustments can make a world of diffference on thinner materials as you said
     
  3. el Diablo Guapo

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    I have too many thoughts on this topic.

    #1 though is: it is dangerous to make/modify stuff and ride it - (also SOOPER FUN!) but also you could get hurt

    so a bunch of things to keep in mind in no particular order (MIG):

    if someting suddenly feels "springy" i assume i just broke a weld and i stop

    welding is not hot glue- it needs to penetrate both peices of metal

    practice A LOT- thicker material is easier to get the hang on, surfaces are easier than tube ends, ends to surfaces are tricky - definitely smart to start on things that don't support a human (yard art, f'rinstance)

    HOW you put it together matters. i try to have peices stacked on top of one another, or pushing against one another, or inserted into one another- rather than relying strictly on the weld.

    butt joints subjected to shear forces (sideways) are prone to failure

    over heated metal may be prone to bending and failing (breaking) after it is cool

    making long things that act like a lever (chopper forks) puts A LOT of force where you may not expect it. these forces tend to find crappy welds, and bust 'em (particularly when going over a bump at high speed).

    slugging up butt joints makes 'em way way sturdier, and if they do fail, the joint usually stays together. i use full lenngth slugs on my builds. this also makes the frame stiffer, so the "pass it on" game of force to aweak spot continues.

    good fit before welding makes better joints

    excessive grinding of weld may weaken a joint. i leave mine and compare my work to itself over time

    do grind off any coating on the metal in advance- paint really messes up the weld, so does galv, chrome, rust etc. (plus health)

    weld some scarps together then clamp one side in a vise and try to beat the weld apart. try this a few times, see what happens.

    bikes are tough to learn on since the material is thin, and round tube makes it suckier as well, since constant distance keeps the voltage regular, and the sheilding gas in place.

    there is a reason bikes have evloved to look the way they do. creating an object that can take the pounding forces (+ ergonomics) is why bikes are the shape they are. change it at your peril.


    i use a MIG because that is what is available (along with plethora other tools) where i usually build. i actually prefer my flux core machine (fcaw), because i can cause the voltage to drop by running the welding wire out (say 1' - 1 1/2" long) matching the heat to the material thickness (thinness?) with constant sheilding gas. fcaw also does better on rust and crust and paint (remeber health tho). long wire on the MIG causes the sheilding gas to disappate= nasty weld - can be challenging to dial it in


    welding my chopper mopeds is one of the most satisfiying things i do.

    keep in mind there is risk involved with welding your own setup.

    practice

    think



    whew! at least as long as i feared
    el
     

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    #23 el Diablo Guapo, Mar 26, 2017
    Last edited: Mar 26, 2017
  4. MEASURE TWICE

    MEASURE TWICE Active Member

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    Did you by chance just stumble upon letting the wire go longer to the weld area. I did that with the expensive gas, could have just shut the valve off all together. It does seem that thinner stuff can be welded past the A setting for amps. A B C D with D being highest. Just I have the small spool of flux core that came with the MIG I never used. May try it to see like you have.

    There may be a day that I put together a additional control that is a fine adjust for the 4 only setting I have on this 130 welder. Maybe a longer cup to contain the shield gas, but the wire would probably touch too soon from the curvature that is normal past the tip where circuit is continued to the wire.

    The Miller rather than the Hobart costing twice as much with the continuously adjustable in the blue painted jobba would have been nice. Anyway nearly 1/4 inch angle iron welded even on C setting. They say it does not do that thick.

    http://motorbicycling.com/attachment.php?attachmentid=85289&d=1490530312
     
    #24 MEASURE TWICE, Mar 26, 2017
    Last edited: Mar 26, 2017
  5. curtisfox

    curtisfox Active Member

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    Don't forget, to never cool the metal with water after welding. It will crystallize the metal, and make it brittle and brake easier. .............Curt
     
  6. el Diablo Guapo

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    MT- moving the wire longer causes a voltage drop, so less heat. I had a stint in a parade float shop about a decade ago and the "real" welder on staff showed me a few foundational concepts that really helped. like be sure the work area is well lit.
    if you switch to fcaw you will (almost certainly)need to reverse the polarity of the power supply inside your welding machine

    CF- sometimes i quench mine in a bucket of used motor oil. supposedly case hardens it. definitely impresses bystanders.
     
  7. curtisfox

    curtisfox Active Member

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    Best to let it cool naturally, lot less chance of cracking. Quenching is for tools knifes and such..Cast iron has to be preheated and then cool slow in sand or be turning down the heat slowly................Curt
     
  8. MEASURE TWICE

    MEASURE TWICE Active Member

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    Thanks... I just thought, like the wiper on a wire wound variable resistor, I could wind up some weld wire. Or a slide connection... but second thought maybe too much being unreliable connection. A few more dedicated length sections of wire added in the circuit, but away from the tip, so it still is in the circuit then shield gas could be used. Also kind of for sheet metal -A, -B, -C, -D and the like using switch that adds in series resistance. The UL symbol if it is there would be out the window though.

    Would like to see what is inside the continuous adjustable rigs have and determine if what I am thinking is right, or just duplicate if not more expensive than replicating.

    MT
     

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