[GlenR]

Hey,

So I've got a mig and tig at work, however, have never used a mig before and using the TIG is painfully slow for alot of the work that's been given to me lately, so would like to become proficient at using the mig. Have read most of the mig books and seen the DVDs but one thing seems to confuse me a bit.

How much heat do you set? I can tune the wirefeed to the voltage just fine, but when do you know you've got too little or too much voltage/heat? Assuming to little results in cold lap / overlap but it would also seem once you start to get good fusion/toe in, that you can just ramp the power up and travel faster through a pretty large range to get a similar weld.

So what is the go, Do you just set it such that you get good fusion and leave it, or ramp it up as fast as you can control the weld puddle?

Here's my first tries with MIG.

17v and 110amps (its a wierd machine that has amps not wirefeed but it does the same thing).



18.5v 135amps



Some critique would be appreciated too. I need to practice keeping my arc length steady i know that much but aside from that it seems the fusion is okay.

So yeah! What's the go with setting up volts?

Thank you muchly
Glen

[weldin mike 27]

Hey mate,

That can be be a problem with the mig, Finding the sweet spot. Mainly, as you said, you can lay a weld that "looks" good but you are never really sure whether it is "good"

I can tell you, that those welds look very good for a start. The easiest way to set a machine is to turn the wire feed right down, start doing runs and then gradually turn the feed speed up, observing the changes, It will start at a hiss, with an unweldable arc, and as you add wire it gets more crackle to it, Depending on your overall heat, the sound will vary from a machine gun to a bacon frying to a real sizzle. Then as you start to get towards too much wire, the arc gets a little noisier and it will be a rougher action, jumpy starts and the pool will roll over in front of the arc,

The sweet spot is just on the lower point of wire for a given heat, so you can burn in but still form a nice weld. Once you are happy with a setting, make a test joint and belt the living shit out of it with a sledge hammer. If the steel bends before the weld lets go, you can be confident in a good setting,

BTW always lead with your arc, dont allow too much of the molten metal to flow in front. Thats where cold lap happens. If the welds arent big enough using this method, Increase your heat settings untill you can achieve a sound weld of the required size. If you mearly slow down, the weld will roll in front of the arc.

There is a miller weld calculator app available on android and apple, that may help.

Good luck. Mick

[WerkSpace]

When I first learned to weld, I would get some scrap material and purposely burn holes in it. Then, I would practice filling in the holes. This same method applies to any form of welding. If you are able to burn a hole in something, your penetration is obviously too much, but when you practice filling in that hole, you soon learn how to control the heat and penetration.

[Otto Nobedder]

Here's a series of charts. Some recommed wire thickness for the metal welded, others recommend voltage/wire speed ranges for different wires and thicknesses of the workpiece.

Good reading, and some worth saving.

http://www.bing.com/images/search?q=mil ... &FORM=IGRE

Remember, these are starting point, to be fine-tuned to your machine and your technique.

BTW, if those pics were "first attempts", you're well on your way!

Steve S

[Otto Nobedder]

Glen,

One critique. In your second picture, the end of the weld (bottom) shows serious undercut/underfill.

The technique to prevent this is to "button off" the weld. When you reach the end of the weld (in any postion) and stop, wait about 1/2 to 1 second without moving the gun, then hit it again until you fill in the void, again without moving the gun.

Steve S