MIG welder update

[Des Quilty]

Liam and I played around with the MIG yesterday afternoon. 

Fixed one problem where the wire coil was not on the spike which stops it from overrunning, when starting and stopping welding, which had caused poor spooling and wire feed issues.

However the MIG still wasn't welding properly although you could just about get an arc going.

We tried some variations and found that lower power settings seemed to work better, but still not good. 

It seemed that the welder was working better with pure Argon than the Argoshield, but once again still not anything you would call satisfactory. 

The main issue is that the arc burns up the electrode wire rather than arcing at the work surface. There was also a lot of smoke created.

We tested using steel that we had cleaned off using a flap wheel. 

We tested the actual gas flow from both gasses and that was satisfactory. 

Perhaps the next step would be to measure the welder voltage/ampage output, but presume that this would have to be under load to be of any use. No idea how to do that in practice..

Would also be interesting to test a fresh bottle of Argosheild.

Thoughts appreciated..

[Matt Rutter]

Hi Des... Measuring the output would be pretty easy... While welding, the voltage should be under 50V, so safe enough to probe with a meter, although this would have to be done inside the case. Measuring the current is even easier. A suitable clamp meter around the earth cable would do it. I have a clamp meter up at the space, but I cant remember its current rating.. I'll check it out later...

Matt 

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[Matt Rutter]

I can measure up to 100A, which is high enough for most MIG jobs.

[Des Quilty]

Manual for very similar model is here..

https://assets.sealeyb2b.co.uk/PDFs/Instructions/MIGHTYMIG190_V2_DFC0161352.pdf

Sealy website suggests that welding current is up to 180A (suppose there is a hint in the name!)

In the troubleshooting section it mentions that a blown rectifier can cause issues..

Probably worth having a gander at the control PCB and associated components and see if anything looks like its on the way out, didn't get a chance to do that on Sunday, perhaps there is something simple like the blown capacitor in the TIG which needs replacing..

Thx

Des

[Dean Forbes (PERS)]

I had a look yesterday the gas is Argoshield Light which is correct

https://www.boconline.co.uk/en/products-and-supply/industrial-gases/shielding-gases/argoshield/argoshield-light/argoshield-light

Matt voltage depend on whether you are doing Short Circuit, Globular, Pulse or Spray Transfer. 

short circuit which sounds like frying bacon is around 17.5 volts 

Short Circuit 17.5 Volts  

Globular 20 Volts 

Spray Transfer 28 Volts 

[Matt Rutter]

Thanks, Dean

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[Matt Rutter]

I've had a look at the MIG welder, and it's now working beautifully.....   The issue was that the welding tip could not be screwed fully into the holder. This meant there was a higher than normal resistance in the welding current path, which created lots of heat, and caused the tip to melt.

I fixed this by running a makeshift tap (an M6 bolt with a couple of longitudinal saw cuts in the thread) into the tip holder. The tip now screws in fully.

I have tested the welder on some scrap, on power settings between 2 and 4 (out of 6), and it's all good.

Matt

On Tuesday, 17 December 2019 09:50:52 UTC, Des Quilty wrote:

[Des Quilty]

Well done, 

I blew out all the dust from the transformer side when I was up on Sunday evening so I could have a quick look at the circuit board for blown capacitors..

Couldn't see any and glad to see that it is indeed the case that the caps are good.

[Dean Forbes (PERS)]

sound like the machine has been used with out being checked first 

If it is used with parts loose they will over head and potentially end up unserviceable incovenicing many members 

That said the machine is a cheap basic budget box and whilst it should fire and put down a seam of weld I definitely do not have high expectations in terms of the quality or consistency of the weld 

Just a reminder it is standard practice to check all machinery before use and this applies to the MIG welder too 

On Tuesday, 17 December 2019 09:50:52 UTC, Des Quilty wrote: