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Thread: ER70-S6 MIG wire

  1. #1
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    Default ER70-S6 MIG wire

    20 years ago I bought a Century MIG welder. It came with a spool of wire marked "ER70-S6." It was easy to grind, and soft enough to mill, drill, and tap, like when welding up and putting a new threaded hole back in the proper place.

    When it ran out I bought a spool of "Forney" brand ER70-S6 at the local hardware store. It's hard to grind, and hard enough a file won't bite without considerable pressure. A high-speed steel drill bit just dulls. Forney wire is about all I can buy locally.

    I've been through a couple of other brands of ER70-S6, plus a roll of something called "EZ-Grind", which wasn't, particularly. The specs I've found for ER70-S6 *say* it's supposed to be soft and machineable like the first roll, but that's not how it's working for me.

    All I want is some .028" or .035" "chicken-wire grade" MIG wire. It doesn't have to have umpty-thousand PSI of tensile strength or be harder than a file; it just has to stick stuff together and be about as machineable as plain old hot-rolled angle-iron-grade steel.

    What kind of wire should I be looking for? The "local" welding supply store is 30 miles from here; I have to make a run next week to get the gas bottle refilled. They were unhelpful when I asked them about machineable wire, but if I know what to ask for, they might have what I need on the shelf.

  2. #2
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    Century is a Lincoln brand so perhaps Lincoln's version of that wire would do the job.

    bob

  3. #3
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    Be very careful with the "Easy Grind" since it is low tensile strength and should not be used for anything needing any real strength, it's mostly meant for auto-body work. As far as the ER70-S6 being hard that will be determined to a certain degree by the alloy you are welding with it and of course the cooling rate, DON'T quench in water if you intend to machine the weld. It very well may be the alloy you are welding rather than the wire itself but again the cooling rate can also be a big part of the problem, a small amount of weld on a larger work piece can chill a weld rapidly causing hard areas especially the transition area at the edge of the bead. If you are welding a heavy section then pre-heating to 400 degs or so and allowing the work to air cool will make huge difference in the hardness of the weld.

  4. #4
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    I hear people complain about mig welds being hard.I have always used 70S-6 wire and have never had an issue.....grind it,drill it,mill it.
    If you are buying 2lb or 12lb spools you will more than likely get 70S-6.I wanted to try ESAB brand EZ Grind but had no interest in paying 8.00 a pound when 70S-6 is 3.00 a pound.

  5. #5
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    Quote Originally Posted by BigMike782
    I hear people complain about mig welds being hard.

    The usual reason for this is what I mentioned above, rapid chilling of the weld. Since most of the time the ER70 wire is going to be a very small diameter with a very low heat input (in relation to the work piece) the base metal will sink off the heat rapidly chilling the weld bead, pre-heating to 400 deg or so makes a big difference! ER70 wire machines easily if properly used but because of it's usually small diameter and resulting bead size the operator often overlooks the fact that the weld can be cooled much too rapidly and of course water quenching is just begging for problems!
    Last edited by radkins; 05-18-2012 at 11:14 AM.

  6. #6
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    Hmm... the problem part that broke the camel's back was 1/4 inch hot rolled steel flat. Come to think of it, most of the hard weld problems have been on thicker sections. I'll try drilling and welding up some holes on some 1/8" and 3/16" and see what happens cold, then try preheat if they're too hard to tap.

    Thanks, guys!

  7. #7
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    It does make a big difference, I do quite a bit of shaft, gear, etc build-up (gota keep them farmers happy! ) and if a large part is not preheated then hardened welds and weld areas usually result. Another thing you might try in order to see if cooling is the problem, and I am willing to bet it is, would be to reheat a welded part to red hot then air cool to see if that softens it. If it does then rapid cooling is most likely the problem.

  8. #8
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    (Somewhere, there's an 'emoticon' for the old forehead slap)

    I had this very problem years ago. I was building up (MIG) a worn-out area with a weld so I could machine it back to the original un-worn state. (I was inspired to use this method by another poster to HSM.) I thought I was putting excessive heat into the weld, resulting in a very hard (and difficult to machine) build up. I got around the problem by using less heat and many more passes. If I'd known I could basically anneal by preheating, I could have saved myself a bit of effort.

  9. #9
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    Wouldn't be of much help for building up a round bar but for a flat weld that has a finished weld of overlapping beads, basically any weld that's more than two beads wide, always try to finish the weld with the last bead near the center of the weld and never with the last bead on the edge. This is true whether the weld is to be machined or not since finishing with the last bead on the edge leaves a hard more brittle transition area between the weld bead and the base metal. This normally happens when a bead is run along the edge but if the weld is then finished toward to center the successive overlapping beads will anneal this hardened area leaving not only a more easily machined weld but also a stronger weld. Never finish a weld with the last bead on the edge.

  10. #10

    Cool

    I use HTP welding wire and it machines and drills well. I know i am always fixing mine or someone elses mistakes I get it off ebay
    http://www.ebay.com/itm/2-10-lb-Roll...item27be5cfd0c I also order tips and nozzles with it because they ship for free. Just my thoughts...Bob
    Bob Wright
    Salem, Oh Birthplace of The Silver & Deming Drill

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