Spot welding with a Dynasty 200DX

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I tried this on the Miller forum, being a Miller specific question but got no answer. There are plenty of Dynasty owners on here so maybe someone has an answer:Does anyone regularly use this feature? I haven't tried it yet but I thought it might come in useful when tacking up jobs. E.g. I'm about to build a cart for the Dynasty and it will have in the order of 200+ tacks. If I use regular RMT STD, then that's a whole lot of wasted postflow argon. If the spot feature reduces the argon usage I could just enable it, ramp up the amps and do all my tacks hopefully using a minimum of gas and then go back to the regular settings to weld it up. I guess I'm kind of hoping that if I set e.g. 0.1s spot time and max out the amps, it will tack properly and only postflow for a second at most since nothing will really heat up that much in that short time. Is that how it works? Or does the postflow still flow for (per the manual) a minimum of 8 seconds regardless of arc time?
Reply:Huh? I have the 280 DX. Have I missed something, or do you have features I don't?
Reply:I'll bet I don't. I'd be very surprised if the 280 doesn't have more than the 200 unless they decided no-one used the feature.- In my Owner's Manual Operation section, Factory Parameter Defaults And Range And Resolution, Spot is an On/Off parameter that defaults to Off. Spot Time is a 0.0 - 999 Seconds parameter that defaults to 0T.- Further down in the Owner's Manual Advanced Section is a section called Spot Enable. Turn the encoder to turn spot on and off, turn it to set spot time, turn it to set amps. Remote becomes a switch only, amperage is controlled at the machine. Works in RMT STD and RMT 2T Hold modes only. My guess is once enabled and set to e.g. 0.1s @ 120A, you stomp the pedal, pedal acts as a controlled momentary switch and that's your output. I thought it would enable a much more accurate way of repeatedly tacking the same way. You can't stomp the pedal on/off for 0.1s manually so the machine does it for you and the amps is an instant on/off burst, not ramping up/down with your foot.I guess my question was somewhere else in my manual it says postflow is 8 seconds minimum or 1s per 10A, whichever is more. And I was hoping with longwinded tack up jobs not to have to flow that much wasted gas. It would be nice if I could just tack, tack, tack within the postflow of the previous tack each time but the nature of most of my projects doesn't allow that. Maybe a sheet metal job project would. It would be nice if I could use Spot and get a 1 or 2s postflow or whatever because I assume that's all it would need. I mean, if I did a 0.1s Spot tack @ 120A, surely I don't need 12s of postflow afterwards?So does anyone use it and is it useful and does it save gas is my question?
Reply:I definitely need to set this up. Will let you know if I can get the post flow down. Did you try just changing the default post flow setting?
Reply:No, I'm relatively new to the machine. But it does imply in the manual that you can't go below 8 seconds or 1s/10A.I guess I should just try both minimizing postflow and the spot function myself and see what happens.Spot sounds useful for tacking and I'm kind of surprised no-one uses it. I can't see how you could duplicate it with any other settings if you wanted to minimize the spot time. You're limited by how fast you can move your foot or thumb in the case of a torch trigger.
Reply:yes, this should work just as you hope.  Terry at welding tips & tricks has a couple videos where he uses this technique to tack up.  He doens't use the functions built into a Miller Dynasty; but rather uses a fingertip switch and sets the power supply to a high amperage.The only caveat is that you must have good, tight fitup at your tackweld locations.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector