Is this thing pumping gas?

[nosfera2]

Hi all,

Bought a 2nd hand Cosmo 100 gas/gasless MIG. I have a few holes I am going to try weld in my camper.

Am busy practising, but the only thing I can't figure out is how do I tell if the gas is coming out?

 

[migmag]

Fsssssssssssssssssssss and no bubbles in your work

 

[nosfera2]

OK, so I should be hearing something when I pull the trigger. Will check tonight.

 

[Lippyp]

Try connecting the gas bottle, opening the valve and pulling the trigger with the welder switched off, you won't have any noise from the wire feed that way. Should be easy to hear it. Are you using disposable cylinders? they really don't last very long at all so are you sure theres gas in it?

 

[nosfera2]

Good suggestion - the wire feeder does make a fair amount of noise. Yes to the disposables. I think there is gas, if I unscrew the regulator slowly I hear a hissing sound. I have heard the disposables don't last long; can that be measured in time? Say 15 minutes?

 

[weldequip]

Disposable Gas Canisters

You should get approximately 20 minutes running time from the Argon/CO2 canisters & about 40 minutes from the straight CO2. These times are CONTINUOUS (at correct flow rates) so in practice it's a fair amount of welding. There is also larger capacity canisters on the market which have about 50% more gas in the same size canister.
If you have a lot of welding to do forget em! & upgrade to the refillable cylinders.
weldequip

 

[malcolm]

You should get approximately 20 minutes running time

The little Halfords disposable bottles are even worse - they hold 60 litres, so at a flow rate of 10 litres per minute they'll empty in 6 minutes. I reckon that's about 1 metre of weld.

Some MIG welders have the gas controlled by a solenoid inside the machine rather than a valve in the torch. On those you won't hear a hiss when the machine is switched off, but the wire feed noise can be reduced by turning the speed down.

No hiss at all anytime is normaally due to the tiny hole in the regulator being blocked - sometimes the reg can be taken apart and blown out with an air hose.

 

[nosfera2]

I didn't hear much hissing, so perhaps mine is a solenoid operated one. I'll take the regulator apart as well, just in case.

 

[timinder]

I recently bought a welder complete with a regulator and had the same problem. I fixed it by taking the regulator apart and turning one of the pads that sit on each end of the spring around. I suspect that it had been incorrectly assembled, as since putting it back together it works perfectly.