Thinking About a Used Stick Welder

[GWIZ]

Originally Posted by threepiece

Is the selenium rectifier shown in the picture below?
This picture is upside down.

A quick look
With the code number it looks like you got lucky
I see diodes,
"No" selenium rectifier.

[GWIZ]

Originally Posted by LKeithR

????? Never heard of copper coated rod. Get some 6013 or 7018 to play with...

Carbon arc rod just for a power test should be ok.

[threepiece]

Originally Posted by LKeithR

????? Never heard of copper coated rod. Get some 6013 or 7018 to play with...

I am referring to TIG or flame welding rod ER70S. These rods have what looks like a copper coating presumably to minimize corrosion. I expect I should be able to test the welder output with this rod first before buying anything else.

[terry lingle]

If it does have selinium rectifiers free is about as high as I would go for any welder.
THe problem is that they are a mechanical assembly rather than a welded and deposited diode in an inert gas Assembly They have a finite lifetime due to the mechanical nature of them and we are about 30 years past the expiry date of any selenium rectifier.
They can be replaced by suitable silicone diodes in stud mount packages but you do need to know what you are doing.
The cost of the diodes and heatsinks will not be cheap. If it has silicone stud mount diodes the life expectancy and availability of parts is much better.

I just rebuilt a newer diesel miller big forty 400 amp welder the diodes were over $800 CDN my cost so be aware of what you are getting into.

[threepiece]

The welder seems to work, although I'm not sure how well yet. I have varying degrees of output relative to the switch setting but it seems weak. I suspect the small lug connector and the long length of 8ga. ground wire I was using contributed to that.

I'll try to go to the scrap yard tomorrow to get more suitable cable.

[GWIZ]

Originally Posted by threepiece

The welder seems to work, although I'm not sure how well yet. I have varying degrees of output relative to the switch setting but it seems weak. I suspect the small lug connector and the long length of 8ga. ground wire I was using contributed to that.

I'll try to go to the scrap yard tomorrow to get more suitable cable.

while you are at the scrap yard look out for a foot pedal you need the one that was for that machine.

Look in the manual and take a picture of the pedal and take a picture of the "connector plug" on the welder so you know what to look for.

[Ironman]

I bought a Thermal Arc 400GMS machine in 1997, as I had sold the 300GMS machine. In different jobsites with many mechanics and such using it, the machine earned praise. I burned a bunch of 1/4" rod with it putting on bucket lips. Then in 2004 I decided to get a Miller 22A wire feeder for it. I plugged it in and it did not work. I had an electrical contractor onsite and I called him, thinking the Miller box was bad. He determined that it was the welder plug that was not feeding power to the 22A. So, as a last resort he chopped off the plug and wired in a 24 volt transformer to the cord so the wire feeder would work.
This went on like that for years, and one day I determined to fix the problem. I studied the schematic and saw a fuse. Ah ha. I opened the case up and saw nothing but circuit boards and heat sinks, etc so I closed it back up. I started looking for a spare welder box and I found one on Ebay about 5 months ago. HGR Surplus refused to sell to me, so Milo bought it for me and I picked it up when we went south.
They had a ton of these machines the 400MST which is a generation newer then mine and these had been Praxair rental units.
Similar to this one. The ones he has for sale now are the older units, still 400 amp, but stick and TIG only.
Anyway, we played with it in Wheatland at Bubba's shop, and it was good, so got it home and wanted to try the wire feeder on it. I had saved the cut off plug all these years, and I took off the xformer and put the plug back on.
Works like a charm, the remote contactor works, now I have not got a hot gun like before, that was a pain in the ass.

So, after all that, I decided to plug in the wire feed cord to the old 400GMS that had been dead. Well shit, that works now, as well.
Some how, after years of running on gen sets, flying on float planes, being everyone's free welder....it has healed it's wounds, and now I have two fully functional machines.
''
When you have a 400 amp machine that weighs 55 lb, you have a 'can I borrow it for the weekend' problem.

[threepiece]

I tried out the welder with a genuine welding rod yesterday. I have no frame of reference but this welder seems to weld nicely. With a 12 ga. primary I was easily able to heat up 3/8" steel with good penetration. The arc seemed quite smooth and easy to control. I tried it on both straight and reverse and found that straight seemed to have better penetration but more difficult to start. I am curious to see what I can do when I hard wire it with 4 ga.

Thanks again to all.

[MetalWolf]

Originally Posted by threepiece

I tried out the welder with a genuine welding rod yesterday. I have no frame of reference but this welder seems to weld nicely. With a 12 ga. primary I was easily able to heat up 3/8" steel with good penetration. The arc seemed quite smooth and easy to control. I tried it on both straight and reverse and found that straight seemed to have better penetration but more difficult to start. I am curious to see what I can do when I hard wire it with 4 ga.

Thanks again to all.

Glad it worked out for ya