Practice Welds (Something wrong with my Miller again?)

[Karateboy]

Hey guys,

I just got my Millermatic 140 with Autoset back from service. I bought my Miller because of its reputation for quality and reliability. Then my gas solenoid went out under 2 hours of use. No biggie- maybe i got a bad draw. It sucked not having my welder for 5 days but that's life.

Now I get it back today and start going through some more practice welds.

Within 5 minutes I finish my first 2lb spool of 0.023''. So I switch the contact tips, the travel wheel, and I install the 2lb spool of 0.030'' mild steel wire and pull out some more practice sheets.

At first I like it. But for some reason the gun "jumps" a little every so often. Over the next 20-30 minutes, the keeps happening more and more often. What it seems like is happening is the wire is coming out of the gun but there is no arc. It hit my plate so hard that it not only pushes the gun up but shakes my plate. Now I'm worried something is else is wrong with the internals and the machine isn't creating an arc

As you can see from the pics, the welds get progressively worse using the same technique and settings.

Picture shown in chronological order. Maybe the machine is overheating? I am not getting the warning light.

Millermatic 140 w/AS
Voltage setting 5
Wire Speed setting 55
16 gauge mild Steel

 

[Iain Westland]

sounds like something to do with the wire feed and an intermittent electrical fault, cant see it tripping due to heat but then again your in yankyville so it could be a hell of a lot hotter than here in backwater

Iain

 

[pedrobedro]

It sounds like you need to slow the feed speed down a bit. They may have altered something which has changed your calibration during the service.

 

[greyshirtguy]

Just a quick thought...

Any chance that swapped over contact tip has worked a tiny loose (creating a poor electrical circuit) ?????
Is the bolt/screw on the "work piece" clamp also nice and tight (making a good electrical connection there as well)?

 

[scott0031]

This might be a stupid thing to say but...................................... the sheet in the later pics looks like its zintec, always a bit hard to tell from pics but seems to be a weird finish for plain old bright sheet or black ground off.

Seems a bit strange as you also don't seem to have the typical symptoms of it being zinc coated IE white deposit and porosity.


If by any chance it is zintec that will be your problem i would say.


Kind regards,


Scott (ward eng)

 

[Karateboy]

Thanks guys for the help.

This might be a stupid thing to say but...................................... the sheet in the later pics looks like its zintec, always a bit hard to tell from pics but seems to be a weird finish for plain old bright sheet or black ground off.

Seems a bit strange as you also don't seem to have the typical symptoms of it being zinc coated IE white deposit and porosity.


If by any chance it is zintec that will be your problem i would say.


Kind regards,


Scott (ward eng)

I definitely regular mild steel. My old camera can make things look weird.




All i did today was reduce the wire speed and things started going well. I barely changed it but it worked.

Here are a few more practice welds. I finally found a semi-comfortable position that helps me keep my hand pretty straight- too bad the metal I was welding couldn't be anymore bent

Please look at only the 3 horizontal welds. The top welds were when my gas solenoid failed.
Front

Back- The metal was even more bent up than it looks where I met the base metal
http://img6.imageshack.us/img6/281/img2824k.jpg[/img


As you can see, only the left side of the welds has brown residue. I think this is because I am welding outside in the wind. I know its not ideal with solid wire but I do not have room in my garage atm.

[img]http://img8.imageshack.us/img8/5079/img2823xpc.jpg


I've noticed that I am burning through at similar distances, let's say every inch, what do you think I should do? When I adjusted the Voltage just a hair I lost the "frying bacon" sound. I'm thinking increase my travel speed. I must be pausing every so often.

 

[Iain Westland]

dont try runs longer than an inch out side then see how you get on welding two pieces together.

Iain

Oh, and looking good sir!!

 

[Karateboy]

Thanks,

I also was advised on another forum to not put a weave in my bead on such thin metal. No weave = less heat = no blow through

 

[pedrobedro]

If it is pushing back at you it's usually wire speed. Put a wind break up outside, a piece of board will do to shield you.