Spot/ resistance welding machine

[chris y]

For so few welds anything that creates enough flow will do, a tank with no cooler would as you suggest would be enough volume of water to not get hot.
The problem you could have is if your pump flow rate is low water might only pass through one way and back out, there may be several circuits in parallel and you need enough flow so some water goes through each.
I would guess that a hosepipe as Robotstar said would work well.

 

[OllyO]

On a meter but I have a few spare bilge pumps from the boat and also a mains sump pump so guessing that'd do.
Anyone know a good operating temp of electrodes? Could always do some tests and keep tabs on them

 

[chris y]

I don't know, of course the working end can momentarily be red hot during the weld but if the arms or much past the first few millimetres starts to change colour they aren't being cooled enough.

A fancy modern cooler will keep the water at about 20 degrees, if you can keep water moving through all of the cooling system and its only luke warm coming out at the end you should be OK.

Never over cool because you can cause condensation which causes all sorts of problems, anything more than 16 degrees will usually be OK.

Of course if you are using it a lot and keeping a nice tank of warm water you start to risk legionella, not that likely to be a problem realistically.

 

[OllyO]

Cheers Chris. Will post how I get on. Thanks for your help

 

[Robotstar5]

Just don't be tempted to do many welds without cooling. A manager asked us to run an automated welding line up on a Sunday morning with no cooling water, he assured us (against our advice) that one machine cycle would be OK, the weld techs spent the next few hours replacing melted tips and damaged toolholders, the manager went home for his dinner

 

[chris y]

Just don't be tempted to do many welds without cooling. A manager asked us to run an automated welding line up on a Sunday morning with no cooling water, he assured us (against our advice) that one machine cycle would be OK, the weld techs spent the next few hours replacing melted tips and damaged toolholders, the manager went home for his dinner

Oh dear, that Manager is lucky you didn't fry more than weld tips and holders, at least they can be replaced easily, had he cooked some transformers or thyristors he might have been going home for a lot longer.
Don't you have water flow switches to prevent that happening?

 

[Robotstar5]

Don't you have water flow switches to prevent that happening?

Yes but the manager wanted them bypassed against our advice.

 

[Rrunnach]

I'll actually be doing a practical exercise within the next few weeks to my lads of spot welding al/al together on a machine that does not have that capability. Neat trick for my lads to know.

I forgot to reply outcome of exercise. 2,off 18swg al/al sandwiched between same gauge mild steel.

Settings: high heat, with long hold and squeeze cycles, resulted with good quality spot welds and, each spot producing a good nugget. Use of machine I have access to, is for mild steel welding/SS, too. method above would be for an emergency spot or two manufacture or repair.

Spot welding al/al using proper machine, secret to avoid blasting holes in work is, good cleaning of tips, four/five spots, clean each tip with rough grit emery.

I can't remember if tip grade differed from lcs to al/al?

 

[OllyO]

Here' a pic of the machine as promised. I purchased it off a bloke I do a lot of trade with. He laid it up a few years back and between then and it arriving at my workshop it's stopped working.
I'm hoping it's just a fuse or loose connection but haven't had a chance to explore it any further

 

[OllyO]

Have checked fuses in isolator box and all is well. Opened up the top and there is what looks like two other fuses (see pic below)

 

[Seadog]

They are fuses. Slide the cover to remove.

 

[Robotstar5]

They are fuses. Slide the cover to remove.

The old Slydlok fuses, been around for many years and still available.

 

[OllyO]

Cheers chaps. Couldn't seem to remove them. Might be being daft but should the holder slide off downwards?

 

[Robotstar5]

Cheers chaps. Couldn't seem to remove them. Might be being daft but should the holder slide off downwards?

They slide to unlock then pull out.

 

[OllyO]

I noticed today that there is a cut off black wire (presuming earth) within the armoured cable on the machine. It's cut short at both ends. The plug only had the three phases connected and nothing on the big earth pin.
I also noticed the machine has three lives going into the isolator box but only two entering the machine.
Any thoughts?

 

[OllyO]

Two lives leaving fuses

 

[OllyO]

And three entering

 

[Wendelspanswick]

It could be a 2 phase machine. With the power disconnected try seeing if you have continuity between any of the wires and the body of the machine to work out which is the earth.

 

[Robotstar5]

Just using 2 phases is quite common, we had literally hundreds of spotwelders in our building and we had to spread them across the phases to balance the supply.

I would advise keeping the machine isolated until you have confirmed the earth connection.

 

[OllyO]

Cheers both, will check this tomo and report back.