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pro welders, I've got a challenge for you to firgure out

16K views 63 replies 34 participants last post by  deadbodyman 
#1 ·
Heres what I need to do.I want to be able to cut off the welding current while not stopping the wire feed...Mabee a foot control or something...what I want it to do is weld the wire to the metal then cut off the current while still feeding the wire out so the wire is welded to the metal then I can cut off the wire from the torch and use the wire to pull dents out...thereby eliminating the need for a stud welder...I need to know if a foot switch is what I want and if so where do I connect it..Is it even possible????
Any thoughts???
 
#44 ·
how about if you maintain a puddle and then while the wire is still dipped in the puddle, quit pulling the trigger on your mig unit. then you can release the drive wheel from pushing your wire through the sheath of your mig lead. pull on the mig handle and the wire will remain attached to the puddle. get out your *****, cut it, and that should do it.
 
#45 ·
wow alot of theory

A diagram of the CONTROL CIRCUIT is needed.:D

Only switch the control power not the main power to the step down transformer or the IGBT or MOSFET in a Welder.

An IGBT /MOSFET doesnt like counter EMF when the ground is pulled off.

Separating the motor control solenoid from the arc firing circuit should be easy

with a diagram.

A foot pedal has a variable rheostat in it ,it doesnt shut current off all at once

it goes from 0-high then high -0, you could put a switch in it for just off and on

like a 15 amp light switch But have to know how much current follows thru the circuit,shouldnt be much at all,unless something else is pulling some amps,on the same control circuit.

I like your idea makes sense good luck with it.:thumbup:
 
#48 ·
reverse logic

It kind of depends on what kind of wire feed you have. Some have a jog switch. If that's the case then I would wire in a remote for that and zap the wire to the dent and then bump the remote to feed the unenergized wire.
Without that feature things get a bit more complicated. There are two possibilities. One is to supply power directly to the drive motor. You need to determine what voltage the motor is and whether it's AC or DC. You'd need to find the source, bypass the controls and use your foot switch to feed it directly. The second it to disable the relay for the main transformer. One big enough to switch the secondary power would have contacts the size of silver dollars so things are done on the primary side. It should be easy enough to install a NC switch in the actuating coil circuit and kill the transformer when you just wanted feed. The problem is if the relay also controls any other parts. Go over the schematic and see if any of this makes sense.
 
#50 ·
welding body work studs

Simple fix....spend $19.00 at Eastwood.com and get their mig tip that is designed to weld on pull studs.....it spaces electrode from work and is cut out so that you'll be able to see what is happening. There is a tube that you load the stud into then pull the trigger....you'll see when to end the weld.
If you still feel the need to do it the hard way...? You'll have a great desigm to copy.
 
#51 · (Edited)
i'm an electrician, not an electronics guy. i googled mig welder electrical diagram and came up with this schematic (page 36 on the manual pdf link). a magic board controls both the arc and the wire feed motor. the simple way would be to interrupt the ground with a relay and a foot pedal.

my way would be to use a relay and a timer: so that when you let of the trigger a timer would kick in for a determined time and power the feed rollers. set for a second and you would have a seconds worth of wire stuck in the puddle, set to zero and it would be a welder. use a time delay relay like this no name timer for $20.

my bigger concern would be the amount of heat and puddle required to make enough puddle to stick the wire to it.

http://www.lincolnelectric.com/lincolnpowermig180.pdf

when i did automated welders we had timers for everything even a timer to reverse the wire feed to pull the wire back for the operator. but those were 600 amp continuous power supplies with separate wire feeds running 7/32 flux core wire at 1 ft per second. now that is some serious welding. 55 feet in 56 seconds to weld the backing plate bracket on a ford super duty axle.
 
#52 ·
Wire is too thin

My advice is to spring for the stud welder. There is a reason that the pros use this. Besides, you can get one cheap from Harbor Freight. I got the 110 volt model and it works great. Also, if the dents aren't too bad, you can heat the dent with a torch and then apply a wet rag to the dent to shrink the metal. I think the wire from a MIG welder is too thin to be able to pull a dent. If you insist on doing this, keep pressure against the metal with the torch wire as you let go of the trigger, then remove the ground clamp and hit the trigger again to feed wire.
 
#53 ·
DBM - have you considered modifying the grounding tip on the stud welder? Braze a couple of tungsten points onto it that are 1/4" from our each side of the stud. Sharpen them to pin points. Hold the gun up against the panel and wiggle it a little and the pin points should cut thru the paint and find ground.
 
#55 ·
I havent thought of that (great idea) but what I did do with the stud welder was connect a ground clamp to the outer ring (like a mig grounded to the car) and short the tip so it didnt need to be pressed ,it welded as soon as it touched the steel (no spring pressure) That was one of my closely guarded secrets..Now the whole world knows and that feature will be out on the next model...
.but the whole point is to modify the mig so everyone can do it not just the lucky few with stud welders...Keeping in mind this is only for small dents...
 
#56 ·
test for challange

Hey,I think you may already have the tools to do what you want. Rather than cut the power to the voltage the way you are thinking add a auxiliary power switch to the wire feed motor.This should do the trick, but the question now is will the wire do the job. Great idea!
 
#59 ·
Hey,I think you may already have the tools to do what you want. Rather than cut the power to the voltage the way you are thinking add a auxiliary power switch to the wire feed motor.This should do the trick, but the question now is will the wire do the job. Great idea!
I'm sure it will, I even made a special leverage (Fulcrum) puller for it when I get it to work pretty cool in itself...

I'm thinking going to a thicker wire 035 may also increse my chances of success that thin wire burns up quick...you can also pull more with the thicker wire...
Anybody tried pulling the ground off to get the wire welded on yet???? its pretty tough...
 
#64 ·
I tried that (while welding) and it works once in a while about 2 out of 10 trys. its very hard to do...
I did try cutting some wire and welding it to the metal and this worked so before I go any farther I'll get my fulcrum puller finshed (homemade)and see if the wire will actually be strong enough to pull a dent...I'm also working on a stud holding attatchmant for the tip so I can weld studs on from my stud welder...This'll work well for the bigger dents...
 
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