A useful metal-working technique

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by bluegoatwoods, Jan 20, 2014.

  1. bluegoatwoods

    bluegoatwoods New Member

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    I've just about perfected a way of making good, stout brackets for mounting to frame tubes, chainstays, etc.

    I can imagine a number of uses for fastening stuff to the bike. Cargo racks, cable & wire mounts, stuff like that. Here's an example.
    finished bracket.jpg
    I started with a caliper to measure the diameter of the tube with reasonable accuracy. In the example below one of the tubes was 43 millimeters across. After a bit of experimentation, I decided that the length of the arc I was going to make should be 2.2 times the diameter. So in this case I needed 43mm X 2.2 = about 94 mm. But you need more for the 'ears'. About 25 mm each works well. So you need 94 + (25 X 2)= about 145 mm total.

    Now find something round and tough that measures 43mm across.

    Sockets work well
    bracket step 01.jpg
    bracket step 02.jpg
    bracket step 03.jpg
    bracket step 04.jpg
    I wouldn't drill the holes you need for mounting until after the bending. Those spots are liable to be a bit weak and might bend there instead of where you want it to.
     
  2. wheelbender6

    wheelbender6 Active Member

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    As Paul Teutul would say, "That's a great idear".
     
  3. BigBlue

    BigBlue New Member

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    Thanks for the tip. I could use this on my current project. Sockets are something I haven't thought of using.

    Wonder if heating with a Map gas torch and OA would make it easier and less likely fatigue the metal.

    Chris
    AKA: BigBlue
     
  4. bluegoatwoods

    bluegoatwoods New Member

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    Well, heating with Mapp or oxy-acetylene no doubt would make the bending easier. but then you'd have to deal with ultra-heat. Not a big deal, of course. But bending it cold isn't all that hard.

    I wonder if a tinkerer with no particular training could actually temper the steel with heat?
     
  5. CTripps

    CTripps Active Member

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    I've heard that heating up the metal and quenching it in used motor oil will help strengthen it, but have never tired it. Something to do with the hot metal picking up the carbon from the used oil.
     
  6. bluegoatwoods

    bluegoatwoods New Member

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    You know what? If the hot steel actually does bind carbon to it's surface, then I'm guessing that would help give it a less-prone-to-rusting surface. Might be good looking as well.

    Though I've had good luck with plain old polyurethane varnish.
     
  7. Desert Rat

    Desert Rat New Member

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    you must bring steel to cherry color.You are exactly right although we used to use a brine solution, (salt water)
    with a layer of used oil about 2" thick in top of bucket, used oil has more carbon content but make sure you temper it back or it will be brittle,
    we usually polished it a little and heat slowly till a straw color.

    you must bring steel to cherry color and hold for about 10 minutes , quench, clean, temper. The higher the carbon the more the pitting after quench. This is called Heat Treating
    hope this helps!

    for surface hardening they have some stuff which is basically cyanide you heat the part cherry dip it in powder. high carbon content surface hardened about .050 deep
     
    #7 Desert Rat, Jan 21, 2014
    Last edited: Jan 21, 2014
  8. Greg58

    Greg58 Well-Known Member

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    Oil will temper it some, I have used new oil to harden cast lead pistol bullets. I just drop bullets from the mould into a open container of oil, be careful it will smoke and possiblely flame up with a large piece of steel.
     
  9. young grease monkey

    young grease monkey New Member

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    that's a nice idea for sure, i cringe at a lot of the motor mounts people come up with because they don't have much support area at all. another thing you could do is cast some jb-weld on the inside of the bend so it perfectly conforms to the tube. For the engine mount I'm building, I ordered tubing from Mcmaster-Carr with the same ID as the OD on my down tube and seat tube. Then I cut it down the middle, cleaned it up and welded one half to my mount plate with some brackets and whatnot, and used automotive muffler u-bolts to clamp the other half-pipe on. I also drove a piece of seat stem deep into the seat tube for extra support. It's gonna be bullet-proof!
     
  10. bluegoatwoods

    bluegoatwoods New Member

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    Yes. JB Weld would be a good idea. Or something like it. It would give perfect symmetry to the grab.
     
  11. Sgt. Howard

    Sgt. Howard Member

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    Some (most) steels will oil-temper, some have to be water quenched- Cherry, hold for 8-10 minutes, quench in oil, polish to white a small part of it, heat to blue, and allow to air-cool... ought to be just fine.
     

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