Spot Welder not doing it's thing

[northwest]

Long story short, this is a Spot Welder at a place I use to do some fabrication and welding. I can use anything in the place as I make myself useful. Latest thing to fix is this spot welder. It worked fine on Tuesday but on Wednesday, nada.
It goes through all the motions, makes all the right noises but doesn't weld, pictures first:

 

[northwest]

Now, this is power in:



240v single phase.
This welder has worked since Adam was a lad and on this 240v input, it now makes all the noises, the relay kicks in, the light comes on on the timer circuit and it buzzes as if to weld, but nothing at the tips. Does anyone have any suggestions as to where to start to look? Rst of the pics:

 

[northwest]

Picture taken from the web to show the machine when the covers are back on:

 

[Screwdriver]

No but if you ever do find out, let me know. My old portable thing did the same. Worked fine then one day suddenly didn't. Ripped it apart, found nothing except an interesting stack of thin copper connectors to form the hinge, put back together and it just worked.

Then after making up some extra long arms for it, it just stopped working.

My gut feeling is it must be corrosion/high impedance somewhere preventing it from being able to connect the high capacity current required. One of these days I'll rip it apart again and investigate properly; clean all the places where high current goes and maybe squirt some contact cleaner in there.

 

[Brad93]

Copper has burnt out/corroded somewhere

 

[bourbon]

Can't help. But I found this. No use I know but hey. Lancashire Dynamo Electronic Products - Graces Guide

 

[oddbob]

I had the same thing with a hand held spot welder a few years back ...made the normal noises, sounded like it should work, but nope. stripped it down and could find nothing. It turned out to be the copper electrode arms (if that's what they're called). They did look a little blackened (especially on the bent sections). Changed them and it was as good as new!

 

[northwest]

Copper has burnt out/corroded somewhere

I am hoping it is something simple like this. To be honest, there is nothing to the machine.

 

[Brad93]

I am hoping it is something simple like this. To be honest, there is nothing to the machine.

I'm betting that's what it is. There's nothing to go wrong with them

 

[northwest]

Well, just to bring this to a conclusion, it was corrosion. As you can see from the photograph I dropped the contact into a bit of Nitric acid and and cleaned the mating services, all good again. The platform on the contact is a sort of ball and socket ad I guess there must have been more than enough oxidation to cause loss of contact:

 

[MCKDAVID]

result.... nice one.

I like simple fixes, me.