P&H Model TWI-150 worth keeping?

[amuller]

I bought this machine over the weekend, but really only for the cables and high frequency box. I don't need another buzz box and it's heavy, top heavy, and all rusty and banged up. Lots of copper in it. Probably OK electrically if switch, cord, and plug replaced. It seems to have the small Miller taper receptacles.

Some people seem to think these machines are something special, and not to be scrapped. Others don't. Any opinions here at the moment?

Thanks!

[rodburner6]

The machine has a much lower voltage drop across the output than a Lincoln tombstone and therefore much easier to start and maintain an arc. Made much beefier than the current generation of low cost welders.

[Northweldor]

I bought this machine over the weekend, but really only for the cables and high frequency box. I don't need another buzz box and it's heavy, top heavy, and all rusty and banged up. Lots of copper in it. Probably OK electrically if switch, cord, and plug replaced. It seems to have the small Miller taper receptacles.

Some people seem to think these machines are something special, and not to be scrapped. Others don't. Any opinions here at the moment?

Thanks!

A story I have heard is that these machines were originally made by a heavy equipment manufacturer who was dissatisfied with the quality of machines they were buying, and decided to make a better quality machine. During the 40s to 60s, they turned out many with a 60% duty cycle or better. Many were sold to the military by the Harnischfeger Corp. of Milwaukee. An oldie-goldie that is worth preserving.

[amuller]

Thanks for the responses. Anybody know what a "1/2 hour rating" means? I notice that the max open circuit voltage is given as 90, and the switch only opens one leg of the input power, so I wonder how safe it is by today's standards. Obviously I can put on a better switch.

[MAC702]

...Anybody know what a "1/2 hour rating" means?

Probably. What's the context?

... and the switch only opens one leg of the input power, so I wonder how safe it is by today's standards. Obviously I can put on a better switch.

The switch is fine, as long as you unplug it before you stick your fingers inside rooting around not knowing what you are doing.

[amuller]

I kinda figured the "1/2 hour rating" was a way of expressing duty cycle but a search mostly turned up stuff about fire resistance of building materials.

[Sberry]

I believe code for welders requires switch disconnect of any ungrounded conductors.

[MAC702]

It won't be the National Electric Code. I don't know what Code is followed by the manufacturers.

[Sberry]

I am not sure how that works? Maybe some kind of agreement. I sure I read/schooled somewhere somehow the switch on the machine is sposed to do the ungrounded conductors. I think it's kind of like cords, there is section for cords caps etc, that applies to connected equipment.

[MAC702]

The disconnect on the wall supplying equipment would definitely open all ungrounded conductors. But the switch on the machine doesn't need to.

[Sberry]

I do believe the switch needs to for welders. Buzzers got double pole switch. I can't recall where it's at but I recall it saying the switch on the machine kind of like how some motors required to have additional protection. I believe the original intent was due to the use of multiple machines wired to common circuit.

[Sberry]

Not that I couldn't be wrong about it as it's been some time but at one point I really fuss over it all with particular regard to welders.

[Sberry]

You guys are going to tempt me to open a book. I would rather not do that.

[MAC702]

Again, I do not know what might be required by whatever code the welder maker has to follow. But the NEC stops at the cord and would be silent about what's inside the Listed connected equipment. UL may have something to say on the matter.

I've worked on lots of different kinds of equipment that internally only switches one leg for its on/off state. But that said, the welders that I've worked on do switch both legs, that I know of. I've not taken all of them apart.

[Sberry]

Do motors stop at the cord? There is a whole section on cords caps that connect to equipment.