Lincoln Tombstone Issue

[Lemo]

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.

 

[Lemo]

The fan continues to run.

 

[Navvet]

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.....

 

[RNeumann]

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........

 

[GLyford]

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?

 

[GLyford]

I wonder if there is anything here you can use:

Lincoln AC-225-S repair

 

[Jeepnford]

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.

 

[ArlyA]

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?

 

[Big Barn]

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...

 

[Industrial Toys]

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.

 

[Lemo]

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.

I appreciate all of the responses. I'm going to try some fresh rod first. The volt meter is a good idea. Maybe I can start at the ends then keep moving down till I find it. It's sitting in the corner. My current problem is too many darn projects.

 

[Industrial Toys]

Yes, too many darn projects! These welders are not complicated. No circuit boards and such. Lincoln is great at offering schematics. Without re-reading the thread, I assume it is a "buzz box", so put meter on AC setting.

 

[hawkeye08]

Might be why it was a cheap Craigslist purchase...

 

[cqaigy2]

I got my Tombstone from my father, he'd not used it for decades. The trouble i found was the nylon had swelled in the amp selector mechanism so that the contact wouldn't easily slide down and make poor contact. Cleaned contacts and lightly sanded the nylon part so that the copper selector would slide easily.

The part that looks like a L was swollen so the copper part didn't slide easily.

 

[dragoneggs]

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

View attachment 549663

Don't blame you! I can't seem to let go of my dad's 1963ish Craftsman Radial Arm Saw. Haven't turned it on in over decade.

 

[cqaigy2]

Don't blame you! I can't seem to let go of my dad's 1963ish Craftsman Radial Arm Saw. Haven't turned it on in over decade.

My dad had one of those radial arm saws too, it had a hard life and among other issues, the on/off switch had been replaced with a toggle switch. I freaked when i saw it sitting high and proud right up on top of the arm.
Told him to not use it till i could find a safer switch, one where an accidental bump wouldn't turn it on.

 

[npalen]

I am a bit puzzled as to why the age or condition of the electrode would cause the welder to quit? Seems like a piece of coat hanger wire would strike and arc. I'm just asking because I don't understand.

 

[Industrial Toys]

I can't see it quitting outright either.

 

[Industrial Toys]

Swamp gas doesn't help much either!

I can see a damp rod being difficult to strike or weld nicely with, but once you get started, doesn't it dry out pretty quickly?

 

[npalen]

Too much satchable reactance interferes with the dielectric constant of the vapor pressure in the rods. :thumbsup: Yep, that's it!

Well I knew that was the problem but just couldn't put it into words.