Summer Project #8: This Old MIG, Completed!

Summer Project #8: This Old MIG, Completed!

Joined: January 1st, 1970, 12:00 am

June 3rd, 2018, 2:45 am #1

As I was cleaning up the shop and preparing to swap the Cutlass axle, I had to clear out the junk that had been stashed behind the other project car (again, not mine, but will be getting it's own posts at some point.)

One of the things parked back there was this old Millermatic 200 wire-feed welder:



This had been given to me several years ago, by a guy that didn't need it anymore, and he said it had issue or needed to be repaired in some manner, and didn't think he could get anything on Craigslist for it. I happily accepted it- hey, packrat, y'know 😁 - but neither needed it right away nor had the time to fool with it.

Moving things around today- especially as it was such a nice day- I rolled it out on the apron and figured I'd give it a quick look. As I said in the other thread, I have some welding and fab work coming up, and a second MIG would be handy- assuming I don't have to pile a bunch of money into it.

Fortunately this isn't a "big rebuild" type job, I basically just needed to determine if the thing even worked, and what, if anything, might need to be fixed. First up, there were two big honkin' lumps of black electrical tape at a couple points on the stinger lead. I unwrapped the mid-cable one and found this:




I don't think that goes through to the gas line, so it's really just a possible short to the main conductor. Not ideal, of course, and I'll look into a replacement stinger later, but for the time being, we need to see if this thing will work first.

So, I just threw a fresh coat of black electrical tape on it. 😁



The other huge lump was under the gun:



I worried about this, as that's an awful lot of tape, making me think the insulation has been broken or burned back or something. Thankfully, nope- it's just the strain-relief sleeve has cracked and is no longer releiving strain on the lead.



If I keep using this stinger, I'll have to make up some kind of replacement strain relief, or see if a replacement can be bought, but again, for the time being, it'll work for testing purposes.

Next up, there was a bunch of tape on the gooseneck of the gun, but that proved to conceal nothing more than the original plastic coating of the neck, badly worn. The tip is, as the Binky guys say, rather perished, and the rest of the nozzle isn't all that stellar either.



The threads turned out to be fine with a bit of cleaning, but I have neither a replacement tip nor any sort of cup at all, so those will have to wait 'til Monday for replacements. (If any can even be found here in town for a gun this old.)

The power plug was wrong for my shop outlets- and of course also wrong for my "conversion dongle" which we made up years ago so  my neighbor and I can swap machines as needs be- so a quick trip over to Homey-D gets me a replacement.



Plug in the gun trigger cable...



... Flip on the power (hardly any capacitors blew out, and no fires started right away, always a good sign) and pull the trigger. Wire fed smoothly and properly as expected.



So, I yanked the old wire out of the stinger, plugged it into the welder, ran some wire through it- seems to move smoothly, looks like the liner is in fairly decent shape- and finished it off by wrapping up the trigger cable and securing it out of the way.



Since I can't actually weld anything with it without a tip or cup (or flow meter or tank of gas, etc.) actual testing will have to wait 'til later in the coming week. For the time being though, I figured I'd attend the chassis a bit before I put it away. The top handle had once been attached with simple sheetmetal screws, which had long since stripped out, so at some point somebody had tack-welded it to the housing.



Someone had tried to repair one hole by attempting to force a regular bolt through the hole, which really didn't work.



Two properly fitting bolts, with nice wide washers and proper nuts, and a little attendance with a rubber mallet and some brute hand strength gets that all sorted out and back to reasonably solid and straight.



And finally, a couple of the missing- and stripped- side panel screws are simply replaced with the next size up screw, which tightened everything up considerably.



Aaaand.... that's about it, really.



I can't do anything else 'til I get at least a cup and flowmeter- although I'll likely borrow the reg off the other MIG before buying a new one, just in case it turns out this machine doesn't work. But still, positive results for a little less than an hours' work- including a trip to the store- and I have no reason to believe the machine won't work.

The sad part is, it has a nearly-full roll of 0.035" wire- something like a 20 lb roll- which has a bit of surface rust on it. I may try unwinding the first few layers to see if I can't save at least 3/4s of it, but I have to be really careful not to let it loose and snarl it.

We'll see how it goes.

Doc.
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Joined: January 1st, 1970, 12:00 am

June 3rd, 2018, 5:11 am #2

Found an eBay supplier for the tips- Two tip adapters (the brass part)  two cup collars, two cups and ten tips, all for seventeen bucks. I can pretty much guarantee you that if anyone carries the old Tweeco parts like this locally, just one cup is gonna cost me $17.

That'll put my total investment in this welder so far at about one hour, and about $28. If it turns out to be mostly or completely nonfunctional, that's not a huge investment.

Sure, the eBay stuff is going to be all cheap import knockoffs, but they're just brass turnings. As long as the threads are decent and the tip holes aren't like 3.85mm and a tapered oval, they should work.

Doc.
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Joined: September 16th, 2014, 7:01 am

June 5th, 2018, 3:09 am #3

Gee. I wonder if you can find a 10 or 20#  bottle of CO2 around a Paintball Store somewhere?  :-P  (Do NOT use the Siphon cylinder!  But if you have a Dewar go for it.)  Gold Gas is overkill for most things, my Challenger (one size down from this one) is perfectly happy with CO2.  But when you do Aluminum or Stainless then you need the exotic stuff. 

The rust on the wire reel might just be on the top surface layer or two, you can try scrubbing it off with a Scotchbrite wheel as it sits and think good thoughts. 

And ask around - if someone who buys at the local Welding Shop has an old-style Tweco gun they'll have the tips and nozzle bits, because a lot of that stuff doesn't change. You may well be pleasantly shocked, since it's Alaska the old goat at the Mine isn't going to throw out a perfectly good gun just because it's old. 

Double check the settings, someone may have switched the polarity for Fluxcore or Spoolgun and forgot to put it back when they put the solid wire roll on it. 
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Joined: January 1st, 1970, 12:00 am

June 5th, 2018, 5:11 am #4

On the gas, I've ran CO2 in my MIGs pretty much since the beginning, because it was cheaper, the tanks lasted longer, and I already had two 20-pounders  for filling paintball tanks. 😁

The only drawback of CO2 is is "spatters" a lot more- when I'm building a quick-and-dirty trailer, that's not really an issue, but when I'm trying to build something that looks good, there's the additional issue of having to sometimes chisel off those little BBs.

I've already ordered a new flowmeter specifically for Argon, or 75/25, and will be switching over to that. The difference in cost is not as significant these days, and the time the tank lasts isn't as important anymore now that I'm not building entire cars with it. 😋 Heck, the last time I filled the 20-pounder on the my old MIG was probably... 2013? Maybe 2014? And it's still better than half full.

Now, all that said, I couldn't stand it- I'm sure it's some OCD thing- and I checked the local supplier for the tips and cups. The gun may be an antique, but the local Tweeco supplier had everything I needed right there in stock- a tip, cup, collar and diffuser came out to a whopping $16, to which I was pleasantly surprised.





I popped the 20-pounder and flowmeter off the Lincoln MIG, hooked it to the Miller, checked everything and gave it a shot.



Not bad, not bad... Not great, but not bad. The good news is the machine works pretty well. The bad news was that I had to lay the stinger out in a wide, gradual loop in order to get it to feed at all, and even then only if I reefed way down on the feed roller pressure.

Which of course means I have a bad liner. I pulled the whole stinger off the machine and took it back to the welding supply- the guy also wanted to have a look at it to see if he could find that strain relief as a replacement. A new liner was another whopping $13, and he even installed it for me. 😁

I brought it home and then, before trying to install it, I loosened the feed rollers completely, and hand-pulled about the top four or five layers off the roll of wire- several hundred feet at least.



That got us down to fairly clean wire underneath, with no more surface rust or dust and dirt. A shame to waste all that wire, but it beats tossing out the whole roll, and it'll keep the new liner from getting clogged with all that gunk.

After that, it'd feed 100% reliably with a light twist on the feed roller pressure, and it didn't care what angle I held the gun at. I tried a bead or two on a bit of thicker stock, and I think it's definitely better, but I'll still need to sit down and fine tune a bit better once I get the Argon hooked up.



However, for the occasional noncritical part, it works, and works well. And so far, with all the parts I've bought, I still only have about $90 in the whole thing, and will only need to lease a tank from here on out.

Doc.
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Joined: January 1st, 1970, 12:00 am

June 8th, 2018, 4:45 am #5

I received my new argon flowmeter today, and got out my spare TIG bottle to try it on the MIG. I also tried swapping to the "low voltage" plug (this old machine uses an external cable and socket for a sort of "high" and "low" range selector)) and got some FAR better welds.



As you can see, especially compared to the last photo in the previous post, that there's a LOT less spatter. The weld still isn't perfect, but it's a whole heck of a lot better than it was, and really just needs a bit of tweaking of the wire speed.

I also got in my selection of new tips and cups, so I'm pretty well set for consumables for the immediate future. I'm gonna call this one Completed as well. 😁

Edit: Total investment, about $90, $15 of which was buying a second tip/cup/diffuser set for .024" in case I decide to go that route (such as for thin auto body sheetmetal.)



Doc.
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Joined: November 7th, 2015, 9:13 am

June 8th, 2018, 4:57 am #6

Every time I saw this thread return to the top of the forum, I have to admit that my first thought on seeing "This Old MIG" was Doc hosting a PBS series where he refurbishes Cold War era Soviet fighter jets.

Also, congrats on a project moved to the "completed" column!
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Joined: October 8th, 2014, 2:05 pm

June 8th, 2018, 1:42 pm #7

kelestra wrote: Also, congrats on a project moved to the "completed" column!
It's almost like Doc is playing Tetris with his shop.
If it ain't broke, I'll fix it!
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Joined: November 10th, 2014, 10:32 pm

June 9th, 2018, 4:13 pm #8

kelestra wrote: Every time I saw this thread return to the top of the forum, I have to admit that my first thought on seeing "This Old MIG" was Doc hosting a PBS series where he refurbishes Cold War era Soviet fighter jets.

Also, congrats on a project moved to the "completed" column!
Glad to see i am not the only one that half expects and old Mikoyan when i see the thread. And that is with my dad being an old hand with welders of all types.
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Joined: June 2nd, 2015, 3:34 am

June 9th, 2018, 9:04 pm #9

This thread disappoints me so many ways.     I was expecting "So not having nearly enough to do,  what with all the other projects including the CNC lathe/Foremen Grill conversion,  the Cutlass rebuild and the Armadillo Catapult on top of my penny-rag furry-porn publishing operation I bought an old Soviet surplus MIG-21 Fishbed off of Ebay for $50."

 
It is possible to commit no mistakes and still lose. That is not a weakness. That is life.
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Joined: January 1st, 1970, 12:00 am

June 9th, 2018, 9:26 pm #10

Baby steps, baby steps. I have to get an aircraft carrier first, just so I have a place to park it.

Hollowed-out volcano lairs being notoriously short of runway space.

Doc.
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