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Mrsmackpaul wrote:
Is this still needed to be done when using a MIG welder ?

Paul

Just use one of these gadgets Paul...

Paul

They never seem to do that now. Blokes like exhaust men would have blown up millions of alternators if there was a problem.

Lang

Think n blo n a alternator now a daze would least of your problem
if U blo the onboard pewter U may have to visit the bank maager with cap in hand
wen weldn keep the earth as close to the job as possable
cya

Some interesting thoughts but it appears none us know for sure

Paul

As already mentioned the exhaust guys never disconnect the battery when using the MIG. Also something rings in the back of my poor memory bank (one only) that connecting the earth as close to the area being welded also had something to do with not causing damage. I think the theory behind that is it makes a short path for the electrikery to make the circuit.

Cobba

Not so much a shorter circuit path but to stop it going through other things. Say you were welding a tag on a wheel for a hubcap and put your earth on the spring there is a good chance you would weld a few balls to the race in the wheel bearings.

My guess is you are not going to have random electric impulses anywhere in the car as the current will take the easiest path between the two clamps so, as you say, shorter the better through a solid unit not having to jump joints or connections.

Lang

cobbadog wrote: As already mentioned the exhaust guys never disconnect the battery when using the MIG. Also something rings in the back of my poor memory bank (one only) that connecting the earth as close to the area being welded also had something to do with not causing damage. I think the theory behind that is it makes a short path for the electrikery to make the circuit.

The Exhaust Shop I Use always puts on, one of those "antizap" gadgets I linked to a few Posts back.. As does the Bloke (Me) who Welds up Cracks in my Trailers truck body. ect.

So if the exhaust place chucks a doodah spark arrestor on and has no problems can we take it that a MIG welder doesnt solve the problem of a collapsing magnetic field causing a spike is still very real ?

And yes, the put the earth or ground lead of the welder on the bit you are welding is to stop arcing across bearings and the like and would make no difference to what Im talking about

With a old stick welder every time you take the electrode off it causes a spike in voltage like your coil when the points open

Unlike your coil it will have a lot more current and at a guess just as high voltage and also it doesn't have a spark plug to absorb the charge

So does a MIG stop this ?

The older ones I would think are exactly the same as a stick welder, just a couple of big coils, a iron core and a couple of tappings

You add a contactor that picks up and drops out with the trigger in your MIG hand piece

I dunno about these new all electronic jobs of today, even the electronic DC suitcase welders that are superb to weld with

I wonder if the electronic welders have a spike every time you stop welding ?


Paul

With the welding; I thought you were meant to put the earth clamp on the item/material being welded to the vehicle.

That way, the current flowed from the electrode (or mig wire) straight into the material and back to the welder. Mounting it anywhere else risks stray currents flowing though the body and (as said) arcing over bearings and electronics (etc)

jon_d wrote: ..... Mounting it anywhere else risks stray currents flowing though the body and (as said) arcing over [strike]bearings[/strike] balls and [strike]electronics[/strike] inner thighs (etc)

I learnt years ago... You should never straddle what your welding on a damp and drizzly day .... Cross braces on a woodchips trailer.... :woohoo: :woohoo: :S :S :S