Lincoln Tombstone Issue

   / Lincoln Tombstone Issue #1  

Lemo

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Joined
Sep 18, 2011
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Tractor
Kioti RX7320
Hoping for a deep thought. Picked up a newer generation Lincoln 225 amp AC welder off of Craigslist. It was obviously barely used, came with 20 lbs. of 7018, helmet, gloves all of which were like new. It had been sitting in a shed for a few years so I took it apart, blew the detritus out, cleaned and greased all the contacts. It blew my thirty amp breaker first thing so I put in a 50 and ran 6-2 cable to the plug, a total run right at 50 feet. The wire cost more than the welder.

I stick welded some years ago, even took a class so I'm raw but not helpless. The problem: I can strike an arc and run a bead for a couple of inches then it just quits. Same on various amperage settings. Grounded directly to the work. After a while I am able to strike an arc again and go another couple of inches then it quits. I'm keeping the arc to less than a rod diameter and dragging the weld. It's almost like there was a thermistor or circuit breaker that is cooling and resetting but I can't identify such an item in the unit. I can't imagine a break in the transformer would behave like that but who knows? The rod is plenty old, could I be getting some kind of slag that is bridging? The puddle still looks ok at the time it quits so it's nothing I can see.

Think it would be worth a try with some fresh rod?

Any thoughts would be appreciated.
 
   / Lincoln Tombstone Issue
  • Thread Starter
#2  
The fan continues to run.
 
   / Lincoln Tombstone Issue #3  
I would suspect your rods are old and damp. Try some new ones or try to bake the rods for a bit. I've had luck putting the rods in an old toaster oven at 200 for an hour.....
 
   / Lincoln Tombstone Issue #4  
Someone with more knowledge will surely chime in but I recall 7018 being a rod that likes DC. 6011 and 6013 are more common for AC.
It may or may not be related to the issue........
 
   / Lincoln Tombstone Issue #5  
The exception being the specially AC formulated 7018, often marked either AC7018 or 7018AC. That stuff usually runs fairly well on an AC only tombstone.

There is a thermister sort of thing for the duty cycle. The welder should run 100% on the circled amp setting and on any below that (75A, maybe?). Above that it can kick out but it usually run on about a 10 minute cycle, but that should be way more then just a couple of inches.

You could open up the case and look for scorched components. Also, double check all the fasteners on the ground clamp and the rod holder. Other than that they are pretty simple, that pretty much leaves wire connections and possibly shorts in the main transformer. I wonder if there are any references out there about what the resistance across the various transformer connections should be?
 
   / Lincoln Tombstone Issue #7  
It might not be related to your problem but I would remove the grease too, unless you used grease specifically for electrical connections. Even then likely not needed.
 
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   / Lincoln Tombstone Issue #8  
Silly question. Have you had the cover off (unplug the machine first!) and checked for lose connections in there? Ya, get that grease cleaned off.

The exception being the specially AC formulated 7018, often marked either AC7018 or 7018AC. That stuff usually runs fairly well on an AC only tombstone.

There is a thermister sort of thing for the duty cycle. The welder should run 100% on the circled amp setting and on any below that (75A, maybe?). Above that it can kick out but it usually run on about a 10 minute cycle, but that should be way more then just a couple of inches.

You could open up the case and look for scorched components. Also, double check all the fasteners on the ground clamp and the rod holder. Other than that they are pretty simple, that pretty much leaves wire connections and possibly shorts in the main transformer. I wonder if there are any references out there about what the resistance across the various transformer connections should be?
 
   / Lincoln Tombstone Issue #9  
The OP may be using a dielectric grease.

But as others have mentioned I would try a new pack of electrodes first - 6011, 6013, 7018AC etc.

We bought this buzz box new in 1965 and the ONLY problem I had in over 50 years was one loose connection inside the box.

Here it is today. Just keeping it for sentimental reasons...

IMG_7357.JPG
 
   / Lincoln Tombstone Issue #10  
When it quits, you might quickly try and take a volt reading between ground clamp and rod holder. I don't know if there is a thermal breaker in there or not. If there is, it might be opening at too low a temperature. I'm thinking this is most likely.
 
 
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