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Welding Question

Post in 'DIY and General non-hearth advice' started by DeePee, Jun 8, 2009.

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  1. DeePee

    DeePee Member

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    I would like to assemble some wire armatures using 1/8" and 3/16" steel rods for a hobby project. I am hoping for durable joints, however the models are for decorative use and therefore don't have any stringent quality requirements. I don't have access to anything more than a standard 120v 15A power source. At this point I have the following:

    Material:
    - 1/8" and 3/16" cold rolled steel rods

    Tools:
    - 250w Soldering Gun
    - Very basic Benzomatic MAP brazing torch
    - I've got my eye on a nice used ARCweld AC-100 stick welder.

    I am expecting to create 300 - 400 welded joints.

    Are any of the above tools suitable for this type of work? I need the joints to be relatively clean, which I appreciate has much to do with experience/practice, but I don't want to fight an uphill battle by using the wrong tools.

    As this is a hobby/whim type project I'd like to avoid purchasing an expensive TIG or MIG unit with bottled gases.

    I would appreciate any feedback you all have to offer.

    Thanks!

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  2. Corey

    Corey Minister of Fire

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    Well, your options are basically soldering, brazing and welding. You could force the soldering gun into service (250W is a pretty big gun, but i'll assume that is not a typo) Of course the mapp gas torch would certainly handle soldering, too. This would probably be the quickest and easiest method, but also the weakest. If the wire is rusty, you'd have to clean and flux each joint then solder it up.

    Brazing would be the next step up the ladder. A mapp gas torch should get hot enough to braze - especially on such small wire, but it will take a fair amount of pre heating. I just brazed some AC tubing this weekend with a mapp torch, but had to switch to oxy acetylene for the sections where heat was pulled out too fast and the mapp couldn't keep up. But it shouldn't be too big of an issue on the thin wire. You can also get phosphorous / copper brazing rods which are self fluxing, or use standard flux - a pretty strong joint and uses your available tools, but may be a bit slow going with the pre-heating time.

    Welding would be the strongest joint, though a stick welder would almost be overkill for 1/8 or 3/16 wire. IMHO, it would almost be more hassle than it's worth. MIG / TIG would definitely be the easy/fast way to go, but as you say, you'd have to purchase expensive equipment. If you do go that way, do get a decent welder - I've tried the $250 "walmart" welders and they were pretty much junk. Though I did buy an airco mig welder on craigslist for $200, rebuilt the rectifier with cheap diodes and it works great.
  3. Gooserider

    Gooserider Mod Emeritus

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    I would probably go for either the soldering or braze approach - Welding on that small a peice of material gets tricky as it heats up so fast you are likely to blow away the peices you are trying to weld just by striking an arc...

    It might be worth getting an Oxy/Acetyline rig instead of MAPP gas - it's a relatively low cost set of tools.

    If you do want to go electric, it is DEFINITELY worth getting one of the new electronic auto-darkening welding masks. HF has them on sale often for $40-50, which is not a bad price for even a conventional glass mask. I always found with the conventional masks the big problem was not being able to see while setting up, or raising the hood, setting up, and then trying to drop the hood w/o moving... With the auto-mask, it is about like wearing dark sunglasses, or maybe a pair of O/A goggles - dark but you can still see OK, and then when you strike an arc the mask automatically darkens to protect your eyes without disturbing your setup, and you can now see by the light of the arc...

    Gooserider
  4. Dune

    Dune Minister of Fire

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    I second both of the above replies, especialy Goose's comment about the oxy-fuel setup. Not a huge investment, gives you the ability to braze quickly, but also weld, cut, and heat for bending or freeing bolts etc. Pur-Ox has a little setup that uses an MC tank, and the torch can also burn acetelyne only, great for sweating pipe.
  5. Cluttermagnet

    Cluttermagnet Minister of Fire

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    Some kind of torch brazing, using bottled gas, IMO. Probably mapp gas at a minimum. I've used those bigger Weller soldering guns. 250W sounds like a lot of heat, but actually that gun is likely not up to this job. Those steel rods are going to work pretty efficiently as heat sinks. They will suck away a lot of the heat and you might never get the equilibrium temperature high enough to melt solder. Further, solder is relatively soft and weak. Its main purpose is to assure good, 'ohmic' (non-rectifying) electrical connections where the metals to be joined have been securely fastened to each other mechanically prior to the application of solder.

    If you insist on soldering, use small diameter tie wires at each point the rods cross. This might help. Allow plenty of time for the solder to melt and flow properly. Use a good flux, and clean up thoroughly with solvent afterwards if you use acid flux. It is very corrosive to metals.

    Go with brazing. You need way more BTU's than that gun can put out. Especially if you need good mechanical strength at all the joints, brazing is the way to go.
  6. DeePee

    DeePee Member

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    Thank you very much to everyone who has replied and helped me out! My initial tests with the soldering gun produced great looking joints, however the majority of them failed within an hour of testing. Even at 250w the process was extremely slow, the observations about giant heat-sinks are very accurate. I practiced some with the MAPP torch this evening. The joints are much stronger than the solder. I'm experiencing a lot of warping in the rods, and the area around each joint is more brittle than before I started. I certainly have a lot of research and reading to do.

    I've got my feelers out for a O/A torch set, I hope it will be more versatile and cost-effective over time.

    Best regards!
  7. brokeburner

    brokeburner New Member

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    hey brother you need to tig weld those bitty little rods mig and stick is gonna blow them away oxy ace is gonna undercut and braze is weak as glass maybe call your local weld shop they do stuff for cheap specialy little side job like that
  8. Corey

    Corey Minister of Fire

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    Interesting you mention the wire becoming more brittle after brazing. Is this some sort of high carbon or high strength wire? This could react to the heat by becoming brittle. I sort of pictured it as run of the mill "hobby" wire which shouldn't really be affected.

    If the wire does have a higher carbon content, you could be quenching it by pulling the torch away and having it cool down fast. The solution would be to back the torch away slowly over several seconds to let the wire cool gradually this would avoid quenching/hardening the steel and making it more brittle. This should also help reduce some of the distortion. For joints you've already done, you can heat them back up and cool them slowly - effectively tempering the metal - and they should be back near the original ductility as well.
  9. Dune

    Dune Minister of Fire

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    Brazing, no such thing really, it is actualy bronze welding, has a tensile strength of 50,000 p.s.i. Mild or unknown heat treatment to high or medium carbon steel is unlikely to exceed 55,000p.si. Sounds like you have had trouble brazing before. Get some know-how, it is an incredibly usefull skill.
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