Is this normal

[roofman]

ive got one of the "giant" chinese migs,a 250 amp and its actually a fab welder with no issues except something which i dont like...after the weld is finnished and trigger released the wire seems to still have a small charge left in it and when i put the torch on my metal welding bench the wire can stick...its just like when you discharge a cap.Is this normal as its never happened in other welders ive owned.

 

[Sparkey]

That's weird...does only the wire stick to the bench or the shroud too?

 

[roofman]

That's weird...does only the wire stick to the bench or the shroud too?

just the wire

 

[shenion]

There are normally bleed resistors on the caps.

You might open it up and see if they might have come loose.

 

[Sparkey]

There are normally bleed resistors on the caps.

You might open it up and see if they might have come loose.

The what kinda thinghy???? what do they do Shenion?

 

[GregEng]

Im guessing by the sounds of it they put a constant small load across the cap to ensure there always discharged?

 

[Sparkey]

what's a cap? (yes i'm a blonde...)

 

[voipio]

Cap = capacitor - which stores charge from the power supply to give smoothed DC. The larger capacity ones tend to by cylinders with a couple of terminals on top and markings on the side including something like 4700uF, 60V, meaning their capacity is 4700 microfarads and voltage rating is 60V. Capacitors will retain their charge, even after the charging source is removed, unless there is a path for current to flow, hence the bleed resistor which is connected across the capacitor to discharge it.

 

[roofman]

bleed restistor...will check this tomorrow. cheers

 

[mike os]

what's a cap? (yes i'm a blonde...)

nothing to be ashamed of.....

 

[Hitch]

Is it just a small spark, or full on welding current?

Had it a couple of times on a migatronic, issue on the board in the feeder.

 

[troppo]

I`ve had that on a few different machines as they age, i dont see it as a problem really. Make a hangre for your torch on the body of the welder so the wire touches nothing and get into the habit of putting the torch onto that when you finish a weld. not always possible and sometimes a pain in the **** i know but it will stop it happening

 

[roofman]

Is it just a small spark, or full on welding current?

Had it a couple of times on a migatronic, issue on the board in the feeder.

just a small spark but enough to stick the wire

 

[roofman]

I`ve had that on a few different machines as they age, i dont see it as a problem really. Make a hangre for your torch on the body of the welder so the wire touches nothing and get into the habit of putting the torch onto that when you finish a weld. not always possible and sometimes a pain in the **** i know but it will stop it happening

yea got a hanger but i dont always use it

 

[gavuk]

My Thermal arc does the same thing ,always thought of it as the capacitors discharging ,wire never sticks though,and welding restarts without any issues

 

[Cobbler]

Just an idea, Is there anything to be gained by adding a smoothing capacitor to a 100a Clarke? I don't think one is fitted from what I remember. Will it improve my welding & make into the dogs watsits?

 

[shenion]

You don't want a large cap as that will increase the minimum current.

Something like 2,200 to 4,700uf at 50V or higher will do. Look for low ESR or "computer grade" caps with screw terminals.

Note, the caps would go across the rectifier; not the output.

It will increase the arc smoothness a bit.

Then you will have the same issue of it being charged. Add a 220 to 500 ohm, 5 watt resistor across it.

 

[Cobbler]

Thanks for the advice, do you think it would be worthwhile or a waste of time?

Cobbler

 

[shenion]

If you can find the cap cheap then it will be worth it.

 

[Cobbler]

Thanks for the advice, I know where I can get second hand induction motor start capacitors, I don't know what value they keep though, I needed start capacitor for a garden shredder & went to the local motor rewinders & they pulled out a huge box and said 'we always save them incase someone needs one' I think they wanted beer money for them.

From my electrical principles at college many moons ago I seem to remember they can be put in parallel & the capacities added I think? Perhaps you can correct me if wrong please.

Cobbler