1976 econo twin hf foot switch

[flamephil]

i just bought an old miller econo twin hf in top shape!!
the only thing missing is the high frequency remote foot switch!!
wanted to know what i need to fabricate one!!it's a three prong twist lock!!
they say i need a single pole single throw switch..
but what amp and volt??what about the cord size???
any help would appreciate!!
thanks

[flamephil]

please anyone!!
i'm waiting for that to start welding my new project!!

[Tinker]

I took a look at the manual that Miller posts on their web site since I'm not familar with this particular welder. According to the manual there is a switch on the front panel that you can use to either select continuous HF or let the remote control activate it. The front panel switch is controlling the HF just the way the remote would do it (i.e. the switches are in parallel) and Miller is using an SPST 16 amp, 125 VAC toggle switch. If you're going to use a foot switch I'd just pick up one of the normally open, momentary contact push switches. Something rated at 125 VAC but I wouldn't get hung up on finding one with 16 amp capacity. Sounds kinda high for a push button, most of the ones I've got laying around are more like 5 amp.

If you want to get fancy you could build the push switch or a microswitch into a simple hinged pedal. Makes it a little easier to hit the switch without looking. My first one just had the button.

As far as wire, I'd just use some standard round extension cord (14-16 gauge) which should have no problem with that voltage and current. Pick something with a nice tough covering since it's going to get stepped and dropped on

Does that give you enough info to start playing around??

[flamephil]

thanks thinker!!
so you think a 5 amp switch would be enough??
the remote plug is a three prong hart lock???
can you draw a diagram of what it should be just to be sure!!
thanks

[dyn88]

there are a few foot pedals on ebay for that three pronged machine.

[cruizer]

The switch is basically used to turn a relay on and off, I doulbt if there is an amp running through it.

Most toggle switches are rated at 10 amp/125 Vac anyways.
Anyhow, someone has replaced the 2 pole receptacle with a 3 pole, It'll be un grounded, so I'd imagine that if you simply jumper the 2 outer plug blades, that'll turn on the HF. If you don't want the HF giving you a headeache or zapping computers and telephone lines, tywrap the first 3 feet of the electrode cables together. And as an added bonus, your arc will run smooth in AC

[Tinker]

Flamephil,

According to the Miller info & schematics they're controlling the power to the HF circuits directly with the local or remote switch, not with a relay. I've attached the schematic from their web site below. Since the schematic didn't give any details on the transformers they're using it's tough to tell just how much current is involved. A normally open pushbutton or momentary toggle should cost that much so I'd just pick up the highest current rating one you can. If it's 5 or 10 amps, give it a shot. I'm guessing it's going to be fine.

You'll see that the Miller info that I've attached just indicates that you should wire the remote switch across the two terminals of the outlet. As Cruizer mentioned, it looks like somebody might have changed the original two prong outlet to a three prong (or maybe Miller changed the design somewhere in the production cycle?). Since the original remote switch only used two wires you're going to have to find out which of the two you need to connect to the remote switch. They may have left the third prong open or grounded it or ?? If you're comfortable opening up the unit and checking how the panel connector is wired, great. If not you could determine which terminals to connect from the outside if you've got or can borrow a volt/ohm meter. We could walk you through the steps or you could just try and find an appropriate pedal on eBay. Let us know what direction you want to go.

[flamephil]

thanks guys!!
i'll give it a shot today and i'll let you know what happen!!

[flamephil]

the switch is finally done and works!!
thanks guys for the help!!