I'm sure you've heard this before...

[joebull05]

Hi guys, tons of great advice being handed out here, just like to say thanks in advance...

Here's my deal: I'm rebuilding an '81 Mini City from the ground up. Currently it's nothing more than an empty shell laying on it's side in my garage. I figured what better place to learn to weld than actually doing it. However, I've currently got a hand-me-down MightyMig100 with a busted trigger. It's always live so I have to turn it off to put it down for the most part. Just wondering if it's worth the trouble to replace the entire nozzle assembly or just break down and pick up a new welder. Whichever the case may be, any suggestions on where to get a new torch or which welder would be best for someone just starting out.

Thanks again,
Joe

 

[rtbcomp]

Welcome to the forum.

If the trigger switches the wire feed on and off OK there's nothing wrong with the trigger or torch.

I've a sneaky feeling that particular machine has a live torch to cut build costs.

Somebody will be along soon to confirm or deny!

 

[greg_is_here]

I would agree with rtbcomp, I had the new experience of gasless Mig the other week with a SIP, went to put a tack in place and the ruddy thing arced out as that one is always live, wasn't a happy bunny

 

[joebull05]

I looked more into it and it does appear to always be live and the trigger is just for wire feed. So the wire feed is always on. Still I think I'm going to be in the market for a new introductory type welder that can keep up with me once I have a slightest clue as to what I'm doing.

 

[GeorgeB]

I'm building my own MIG welder at the moment, cobbling it together with parts obtained from various 'spares or repair' type machines. I started running it with a live torch, simply because it's easy to wire up, and I can make do without a PCB and other things to go wrong. Perhaps because my prior experience is based on arc welding, the live torch feels good and just 'right'. I don't feel I need to go to a non-live torch, although I admit it's early days in my case. If arc welding is accepted with a live rod, what's so bad about a live torch on a MIG welder?

 

[greg_is_here]

Hi GeorgeB, I can see your point about the live torch and I practise in MIG, TIG and MMA. MIG is a much more flexible process and when you start whipping through stuff it's a lot easier when it's not live; however I have a different frame of mind when doing MMA because I am expecting it to be live, it's just what you are used to and most comfortable with really I guess.

 

[stormin]

I started of with a Clarke mig 85en gasless that had a live torch. Seeing as I'd not really used anything else before hand I soon got used to it. The wire usually seemed to burn back to the tip anyway. The next time you used it the arc only struck after pulling the trigger and the wire advanced out close enough to the workpiece, if that makes sense.

Non of my friends could cope with it though whenever they borrowed it as they were all used to more professional sets.

 

[the snooper]

i suppose you could modify a mig with a permanent live torch by adding a relay to the wire feed output so that it switched the main welding transformer.
would have to be a relay capable of handeling at least 13 amps @ 240 volts

 

[GeorgeB]

i suppose you could modify a mig with a permanent live torch by adding a relay to the wire feed output so that it switched the main welding transformer.
would have to be a relay capable of handeling at least 13 amps @ 240 volts

Yes, I think you're right. In my case, I've done the opposite! I threw out the relay because it's one less thing to go wrong. Keep it simple, I say.

I also wonder about the surge of power coming out of the transformer secondary in the case of non-live torch operation. When you pull the trigger on a MIG welder with a non-live torch, some 230v AC is sent through the primary of the main transformer afresh. I wonder if this produces a different characteristic for the first fraction of a second of welding. Is it as desirable as the smooth power delivered by a permanently live torch?

 

[Iain Westland]

I like non live, allows me to put the torch down on the car floor without getting a spark. when doing floors the lid is up / down / up / down, last thing I need is to inadvertently earth it while I sort the panels fit out a bit better

iain

 

[SirDick Diodenob esquire]

George , The transformer inrush current in a distribution circuit is assumed to be 12 times full load current for 100mS , this is the worst case and is used when selecting fuses for the medium voltage (11kV) side and in most cases the actual inrush is nowhere near this . The low voltage mig transformer has a different characteristic than a distribution transformer but works the same way but it also has a choke and sometimes smoothing capacitor on the output which will prevent spikes and will get to a steady state output faster than you can move your torch so the energising inrush current will not affect the welder output . I intend to find out what the inrush current is on my Murex Tradesman Transarc DC135 arc welder(this has no contactor) because its this which is causing a 20amp type B ring main mcb to intermittantly trip rather than the transformer full load current ,once it successfully energises its fine and it also works fine on a 32amp type C breaker with no intermittant tripping so I suspect the 20amp breaker is just cutting it too fine but unfortunately in their wisdom this is what the housebuilder fitted to my house for reasons I dont understand .