Beginner questions X2

[wellingtonrock]

Hi.

I've got a little hobby MIG welder - Telwin summat'r'other. Not terribly nice, wire's always live so it's gotta be handled a bit carefully. Anyway, my questions may be more generally applicable, but I don't know.

First, can someone tell me please, whether the gas flows only when the wire's being fed, or is it flowing all the time the valve is open?

Another one, elsewhere on this forum was some mention of orifices for regulating gas flow. As a newbie, how do I know what size orifice I've got, where is it fitted, and where do I go to get the correct size one? The reason I ask is that the gauge is showing 40 lpm, and I've read here that I should be aiming for 10 or so.

Thanks in advance for your help.

cheers
denis

 

[shenion]

If the gauge is calibrated in LPM, then there would already be an orifice in the regulator.

10LPM is normal. The gas flow should only be on when the trigger is pulled.

 

[ian of fev]

hi there denis firstly the gas should shut off when the trigger is closed if yours is leaking gas out it would need replaceing with a new one in the torch secondley as for the flow rate your right at about 10lpm what sort of reg is it i presume its adustable try cranking it right down and the setting it to 10 lpm on the gage it might be that the flow rate of gas is to high and leaking through the gas valve as for replacement parts pm weldequip on here he maybe able to help you out ian

 

[wellingtonrock]

Thanks for your quick replies!

I don't think that it's leaking, I only wondered how it operated in principle. But Ian's suggestion about 'cranking it right down' sounds like a start to what I do need to know. Crank >>what<< down exactly, that's my issue! I don't know how to adjust the regulator, and another thread seemed to suggest that to change the flow rate one had to change the orifice. There's no obvious knob anywhere on it.

Also, (how) does one prime the gas flow. When I began, for the first five minutes or so, weld quality was very poor - porous, lumpy. Then it settled down to more like what I would expect. Was the gas flushing air out of the tube? Or was it likely more to do with my technique?

cheers
denis

 

[ian of fev]

any chance you could show us a pic of the regulator dennis or what make it is we might be able to help you from there

 

[ian of fev]

what type of gas are you using denis diposible or industial or pub co2 as for priming the gas you shouldent need to once you have conected the gas to the mig the gas should travel instantly to the torch where the gas valve is located and then when you operate the torch the gas should flow nicley

 

[rtbcomp]

If you want to purge without feeding wire release the pressure on the wire feed rollers.

 

[wellingtonrock]

Silly me! The big black knob on the regulator isn't on/off, <shouts> it's a control valve! For controlling the rate of gas flow! So it can be turned up or down! D'Oh!

I've used up the remains of the roll of wire which came with my second hand machine now too. I thought my vernier caliper must be wrong when I measured a sample of it at 0.6mm, but there it is. I had to get some more at Halfrauds 'cause it's Saturday afternoon. Can people tell me whether I'd be better off with 0.8mm for the thin (bicycle) tubing I'll be using once I've finished (butchering) building a trolley for the welder and its gas bottle? Should I be using 0.8 for this job with heavier section metal?

 

[ian of fev]

hi denis you got there in the end with the regulator problem thats what the black knobs for controling the gas flow as for the wire use 0.6 on thiner material and use 0.8 wire for thicker material ian