The recent HF welder discussion got me thinking.
I have a Craftsman MIG. Its got the annoying feature of many cheap MIGs in that the weld wire is always HOT. The trigger on the gun only starts the feed. This is a bit scary and annoying. But i was just thinking, it shouldn't be too hard to add a relay to the switch wiring to change this...
Do you think it would be a simple operation? I sometimes have a hard time wrapping my head around simple wiring issues, so maybe i'm missing an important problem.
Anyone tried this?
Not a real answer, and maybe no help...
But I would just drop $50 on a HF auto darkening mask and set the gun away from the work when your setting things up.
Not quite the same effect, and no cool project... but hey you get to make a trip to harbor freight and it would likely solve the whole blindness problem. Auto darkening is an awesome thing to have anyways.
problemaddict wrote:
The recent HF welder discussion got me thinking.
I have a Craftsman MIG. Its got the annoying feature of many cheap MIGs in that the weld wire is always HOT. The trigger on the gun only starts the feed. This is a bit scary and annoying. But i was just thinking, it shouldn't be too hard to add a relay to the switch wiring to change this...
Do you think it would be a simple operation? I sometimes have a hard time wrapping my head around simple wiring issues, so maybe i'm missing an important problem.
Anyone tried this?
wouldn't the relay need to handle quite a bit of current to do this? also there would be some loss of current across the relay. and theres also going to be a delay from when you hit the trigger to when the wire is hot again, which could make for sloppy work.
problemaddict wrote:
the weld wire is always HOT....it shouldn't be too hard to add a relay to the switch wiring to change this...
Anyone tried this?
Strizzo wrote:
wouldn't the relay need to handle quite a bit of current to do this? also there would be some loss of current across the relay. and theres also going to be a delay from when you hit the trigger to when the wire is hot again, which could make for sloppy work.
A simple no wouldve been sufficient...killjoy
cwh
Dork
5/18/09 11:27 a.m.
Yeah, we refer to kind of work "Epcot engineering". (Mickey Mouse)
I suspect it could be done, the key is that the part you're going to be using isn't a conventional relay, but a contactor. They're the bigger counterpart to relays, often use all solid state parts, and there are versions out there which can handle 50 amps or so.
My HF welder doesn't do that. The Hobart I used once did (it sucked). You shouldn't need a really big relay. Put a conventional 20 amp unit on the primary side of the transformer, not a monster on the secondary. There'd be no loss of current across the relay. A loss of voltage, perhaps, but with a proper relay, that would be very minimal. Wire the relay coil to the wire motor control. When the trigger turns on the motor, it would energize the relay and turn on the primary side of the transformer.
My biggest suggestion with the HF welder is to add a cooling fan. I never had another thermal overload after doing that.
Dr. Hess wrote:
Put a conventional 20 amp unit on the primary side of the transformer, not a monster on the secondary.
You beat me to it, this is the way to go.
